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diff --git a/old/61462-0.txt b/old/61462-0.txt deleted file mode 100644 index d71fbed..0000000 --- a/old/61462-0.txt +++ /dev/null @@ -1,6982 +0,0 @@ -The Project Gutenberg EBook of Standard methods for the examination of -water and sewage, by American Public Health Association - -This eBook is for the use of anyone anywhere at no cost and with -almost no restrictions whatsoever. You may copy it, give it away or -re-use it under the terms of the Project Gutenberg License included -with this eBook or online at www.gutenberg.org/license - - -Title: Standard methods for the examination of water and sewage - -Author: American Public Health Association - -Release Date: February 20, 2020 [EBook #61462] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK STANDARD METHODS FOR THE *** - - - - -Produced by Richard Tonsing and the Online Distributed -Proofreading Team at http://www.pgdp.net (This file was -produced from images generously made available by The -Internet Archive) - - - - - - - - - - STANDARD METHODS - FOR THE - EXAMINATION - OF - WATER AND SEWAGE - - - - _FOURTH EDITION_ - - Revised by committees of the American Public Health Association, - American Chemical Society, and referees of the Association of Official - Agricultural Chemists - - - AMERICAN PUBLIC HEALTH ASSOCIATION - 169 MASSACHUSETTS AVENUE - BOSTON - 1920 - - - - - _Copyright, 1917 and 1920_ - - _By the American Public Health Association_ - ------------------------------------------------------------------------- - - - - - CONTENTS. - - - PAGE - PREFACE TO THE FOURTH EDITION vii - - COLLECTION OF SAMPLES 1 - QUANTITY OF WATER REQUIRED FOR ANALYSIS 1 - BOTTLES 1 - TIME INTERVAL BETWEEN COLLECTION AND ANALYSIS 2 - REPRESENTATIVE SAMPLES 3 - - PHYSICAL EXAMINATION 4 - TEMPERATURE 4 - TURBIDITY 4 - TURBIDITY STANDARD 4 - PLATINUM WIRE METHOD 5 - TURBIDIMETRIC METHOD 7 - COEFFICIENT OF FINENESS 8 - COLOR 9 - COMPARISON WITH PLATINUM-COBALT STANDARDS 9 - COMPARISON WITH GLASS DISKS 10 - COMPARISON WITH NESSLER STANDARDS 10 - LOVIBOND TINTOMETER 11 - ODOR 12 - COLD ODOR 12 - HOT ODOR 12 - EXPRESSION OF RESULTS 12 - - CHEMICAL EXAMINATION 14 - EXPRESSION OF RESULTS 14 - FORMS OF NITROGEN 15 - AMMONIA NITROGEN 15 - DETERMINATION BY DISTILLATION 15 - MEASUREMENT OF AMMONIA NITROGEN 16 - COMPARISON WITH AMMONIA STANDARDS 16 - COMPARISON WITH PERMANENT STANDARDS 17 - MODIFICATION FOR SEWAGE 18 - DETERMINATION BY DIRECT NESSLERIZATION 19 - ALBUMINOID NITROGEN 20 - ORGANIC NITROGEN 21 - NITRITE NITROGEN 22 - NITRATE NITROGEN 23 - PHENOLDISULFONIC ACID METHOD 23 - REDUCTION METHOD 24 - TOTAL NITROGEN 25 - OXYGEN CONSUMED 25 - RECOMMENDED METHOD 26 - OTHER METHODS 27 - RESIDUE ON EVAPORATION 29 - TOTAL RESIDUE 29 - FIXED RESIDUE AND LOSS ON IGNITION 29 - SUSPENDED MATTER 30 - DETERMINATION WITH GOOCH CRUCIBLE 30 - DETERMINATION BY FILTRATION 30 - DETERMINATION OF VOLUME 30 - FIXED RESIDUE AND LOSS ON IGNITION 30 - HARDNESS 30 - TOTAL HARDNESS BY CALCULATION 31 - TOTAL HARDNESS BY SOAP METHOD 31 - TOTAL HARDNESS BY SODA REAGENT METHOD 34 - TEMPORARY HARDNESS BY TITRATION WITH ACID 34 - NON-CARBONATE HARDNESS BY SODA REAGENT METHOD 34 - NON-CARBONATE HARDNESS BY SOAP METHOD 35 - ALKALINITY 35 - PROCEDURE WITH PHENOLPHTHALEIN 36 - PROCEDURE WITH METHYL ORANGE 37 - PROCEDURE WITH LACMOID 37 - PROCEDURE WITH ERYTHROSINE 37 - BICARBONATE 37 - NORMAL CARBONATE 38 - HYDROXIDE 38 - ALKALI CARBONATES 39 - ACIDITY 39 - TOTAL ACIDITY 40 - FREE CARBON DIOXIDE 40 - FREE MINERAL ACIDS 41 - MINERAL ACIDS AND SULFATES OF IRON AND ALUMINIUM 41 - CHLORIDE 41 - IRON 43 - TOTAL IRON 44 - COLORIMETRIC METHOD 44 - COMPARISON WITH IRON STANDARDS 45 - COMPARISON WITH PERMANENT STANDARDS 46 - VOLUMETRIC METHOD 46 - DISSOLVED IRON 47 - SUSPENDED IRON 47 - FERROUS IRON 47 - FERRIC IRON 48 - MANGANESE 48 - PERSULFATE METHOD 48 - BISMUTHATE METHOD 49 - LEAD, ZINC, COPPER, AND TIN 50 - LEAD 51 - ZINC 52 - COPPER 53 - TIN 54 - MINERAL ANALYSIS 56 - RESIDUE ON EVAPORATION 56 - ALKALINITY AND ACIDITY 56 - CHLORIDE 56 - NITRATE NITROGEN 56 - SEPARATION OF SILICA, IRON, ALUMINIUM, CALCIUM, AND - MAGNESIUM 56 - SILICA 56 - IRON AND ALUMINIUM 57 - CALCIUM 57 - MAGNESIUM 57 - SEPARATION OF SULFATE, SODIUM, AND POTASSIUM 58 - SULFATE 58 - SODIUM, POTASSIUM AND LITHIUM 58 - POTASSIUM 59 - LITHIUM 60 - BROMINE, IODINE, ARSENIC, AND BORIC ACID 61 - BROMINE AND IODINE 61 - ARSENIC 63 - BORIC ACID 63 - HYDROGEN SULFIDE 63 - CHLORINE 64 - DISSOLVED OXYGEN 65 - ETHER-SOLUBLE MATTER 69 - RELATIVE STABILITY OF EFFLUENTS 69 - BIOCHEMICAL OXYGEN DEMAND OF SEWAGES AND EFFLUENTS 71 - RELATIVE STABILITY METHOD 71 - SODIUM NITRATE METHOD 72 - - ANALYSIS OF SEWAGE SLUDGE AND MUD DEPOSITS 73 - COLLECTION OF SAMPLE 73 - REACTION 73 - SPECIFIC GRAVITY 74 - MOISTURE 74 - VOLATILE AND FIXED MATTER 74 - TOTAL ORGANIC NITROGEN 74 - ETHER-SOLUBLE MATTER 75 - FERROUS SULFIDE 76 - BIOCHEMICAL OXYGEN DEMAND 76 - - ANALYSIS OF CHEMICALS 77 - REAGENTS 77 - SULFATE OF ALUMINIUM 78 - INSOLUBLE MATTER 78 - OXIDES OF ALUMINIUM AND IRON 78 - TOTAL IRON 79 - FERRIC IRON 79 - FERROUS IRON 80 - BASICITY RATIO 80 - LIME 80 - SULFATE OF IRON 81 - INSOLUBLE MATTER 81 - IRON AS FERROUS SULFATE 81 - ACIDITY 81 - SODA ASH 82 - INSOLUBLE MATTER 82 - AVAILABLE ALKALI 82 - - CHEMICAL BIBLIOGRAPHY 82 - - MICROSCOPICAL EXAMINATION 89 - MICROSCOPICAL BIBLIOGRAPHY 91 - - BACTERIOLOGICAL EXAMINATION 92 - APPARATUS 92 - SAMPLE BOTTLES 92 - PIPETTES 92 - DILUTION BOTTLES 92 - PETRI DISHES 92 - FERMENTATION TUBES 92 - MATERIALS 93 - WATER 93 - MEAT EXTRACT 93 - PEPTONE 93 - SUGARS 93 - AGAR 93 - GELATIN 93 - LITMUS 93 - GENERAL CHEMICALS 93 - METHODS 93 - PREPARATION OF CULTURE MEDIA 93 - TITRATION 93 - STERILIZATION 94 - NUTRIENT BROTH 95 - SUGAR BROTHS 95 - NUTRIENT GELATIN 95 - NUTRIENT AGAR 96 - LITMUS OR AZOLITMIN SOLUTION 96 - LITMUS-LACTOSE-AGAR 97 - ENDO’S MEDIUM 97 - COLLECTION OF SAMPLE 98 - STORAGE AND TRANSPORTATION OF SAMPLE 98 - DILUTIONS 98 - PLATING 99 - INCUBATION 99 - COUNTING 99 - THE TEST FOR THE PRESENCE OF MEMBERS OF THE B. COLI GROUP 100 - PRESUMPTIVE TEST 100 - PARTIALLY CONFIRMED TEST 101 - COMPLETED TEST 102 - APPLICATION OF THESE TESTS 102 - EXPRESSION OF RESULTS 103 - SUMMARY OF THESE TESTS 104 - INTERPRETATION OF RESULTS 106 - DIFFERENTIATION OF FECAL FROM NON-FECAL MEMBERS OF THE B. - COLI GROUP 106 - METHYL RED TEST 107 - VOGES-PROSKAUER TEST 108 - ROUTINE PROCEDURE FOR BACTERIOLOGICAL EXAMINATION 108 - BACTERIOLOGICAL BIBLIOGRAPHY 110 - - INDEX 113 - - - - - PREFACE TO FOURTH EDITION. - - -The Committee on Standard Methods of Bacteriological Water Analysis was -reorganized in 1918 with the following membership: F. P. Gorham, -chairman, L. A. Rogers, W. G. Bissell, H. E. Hasseltine, H. W. Redfield, -with M. Levine as adjunct member. This committee made a report in 1918 -which was not acted on by the Laboratory Section, and in 1919 made a -revised report, recommending certain changes in Standard Methods, which -were adopted by the section and which are now incorporated in this -present fourth edition. - -Following are the more important changes: - -New brands of peptone authorized. - -Phenol Red Method of Hydrogen-ion Concentration. - -Five-tenths per cent of sugar specified for broths instead of 1 per -cent. - -Sterilization of sugar is media specified in greater detail. - -Preparation of Endo Medium. - -Synthetic Medium for the Methyl Red Test. - -There are no changes in the chemical methods in this edition. - - - - - AMERICAN PUBLIC HEALTH ASSOCIATION. - _LABORATORY SECTION._ - STANDARD METHODS FOR THE EXAMINATION OF WATER AND SEWAGE. - -Compiled and revised by committees of the American Public Health -Association and the American Chemical Society and referees of the -Association of Official Agricultural Chemists. - - - - - COLLECTION OF SAMPLES. - - - QUANTITY REQUIRED FOR ANALYSIS. - -The minimum quantity necessary for making the ordinary physical, -chemical, and microscopical analyses of water or sewage is 2 liters; for -the bacteriological examination, 100 cc. In special analyses larger -quantities may be required. - - - BOTTLES. - -The bottles for the collection of samples shall have glass stoppers, -except when physical, mineral, or microscopical examinations only are to -be made. Jugs or metal containers shall not be used. - -Sample bottles shall be carefully cleansed each time before using. This -may be done by treating with sulfuric acid and potassium bichromate, or -with alkaline permanganate, followed by a mixture of oxalic and sulfuric -acids, and by thoroughly rinsing with water and draining. The stoppers -and necks of the bottles shall be protected from dirt by tying cloth, -thick paper or tin foil over them. - -For shipment bottles shall be packed in cases with a separate -compartment for each bottle. Wooden boxes may be lined with corrugated -fibre paper, felt, or similar substance, or provided with spring corner -strips, to prevent breakage. Lined wicker baskets also may be used. - -Bottles for bacteriological samples shall be sterilized as directed on -page 98. - - - INTERVAL BEFORE ANALYSIS. - -In general, the shorter the time elapsing between the collection and the -analysis of a sample the more reliable will be the analytical results. -Under many conditions analyses made in the field are to be commended, as -data so obtained are frequently preferable to data obtained in a distant -laboratory after the composition of the water has changed. - -The time that may be allowed to elapse between the collection of a -sample and the beginning of its analysis cannot be stated definitely. It -depends on the character of the sample, the examinations to be made, and -other conditions. The following are suggested as fairly reasonable -maximum limits. - - _Physical and chemical analysis._ - - Ground waters 72 hours - Fairly pure surface waters 48 " - Polluted surface waters 12 " - Sewage effluents 6 " - Raw sewages 6 " - - _Microscopical examination._ - - Ground waters 72 hours - Fairly pure surface waters 24 " - Waters containing fragile organisms Immediate examination - - _Bacteriological examination._ - - Samples kept at less than 10°C 24 hours - -If a longer period elapses between collection and examination the time -should be noted. If sterilized by the addition of chloroform, -formaldehyde, mercuric chloride, or some other germicide samples for -sanitary chemical examination may be allowed to stand for longer periods -than those indicated, but as this is a matter which will vary according -to circumstances, no definite procedure is recommended. If unsterilized -samples of sewage, sewage effluents, and highly polluted surface waters -are analyzed after greater intervals than those suggested caution must -be used in interpreting analyses of the organic content, which -frequently changes materially upon standing. - -Determinations of dissolved gases, especially oxygen, hydrogen sulfide, -and carbon dioxide, should be made at the time of collection in order to -be reasonably accurate, in accordance with the directions given -hereafter in connection with each determination. - - - REPRESENTATIVE SAMPLES. - -Care should be taken to obtain a sample that is truly representative of -the liquid to be analyzed. With sewages this is especially important -because marked variations in composition occur from hour to hour. -Satisfactory samples of some liquids can be obtained only by mixing -together several portions collected at different times or at different -places—the details as to collection and mixing depending upon local -conditions. - - - - - PHYSICAL EXAMINATION. - - - TEMPERATURE. - -The temperature of the sample, if taken, shall be taken at the time of -collection, and shall be expressed preferably in degrees Centigrade, to -the nearest degree, or closer if more precise data are required. The -thermophone[109] is recommended for obtaining the temperature of water -at various depths below the surface. - - - TURBIDITY. - -The turbidity of water is due to suspended matter, such as clay, silt, -finely divided organic matter, microscopic organisms, and similar -material. - - - TURBIDITY STANDARD.[110] - -The standard of turbidity shall be that adopted by the United States -Geological Survey, namely, a water which contains 100 parts per million -of silica in such a state of fineness that a bright platinum wire 1 -millimeter in diameter can just be seen when the center of the wire is -100 millimeters below the surface of the water and the eye of the -observer is 1.2 meters above the wire, the observation being made in the -middle of the day, in the open air, but not in sunlight, and in a vessel -so large that the sides do not shut out the light so as to influence the -results. The turbidity of such water is arbitrarily fixed at 100 parts -per million. - -For preparation of the silica standard dry Pear’s “precipitated fuller’s -earth” and sift it through a 200–mesh sieve. One gram of this -preparation in 1 liter of distilled water makes a stock suspension which -contains 1,000 parts per million of silica and which should have a -turbidity of 1,000. Test this suspension, after diluting a portion of it -with nine times its volume of distilled water, by the platinum wire -method to ascertain if the silica has the necessary degree of fineness -and if the suspension has the necessary degree of turbidity. If not, -correct by adding more silica or more water as the case demands.[A] - -Footnote A: - - This method of correction very slightly alters the coefficient of - fineness of the standard, but does not noticeably affect its use. - -Standards for comparison shall be prepared from this stock suspension by -dilution with distilled water. For turbidity readings below 20, -standards of 0, 5, 10, 15, and 20 shall be kept in clear glass bottles -of the same size as that containing the sample; for readings above 20, -standards of 20, 30, 40, 50, 60, 70, 80, 90, and 100 shall be kept in -100 cc. Nessler tubes approximately 20 millimeters in diameter. - -Comparison with the standards shall be made by viewing both standard and -sample sidewise toward the light by looking at some object and noting -the distinctness with which the margins of the object can be seen. - -The standards shall be kept stoppered, and both sample and standards -shall be thoroughly shaken before making the comparison. - -In order to prevent any bacterial or algal growths from developing in -the standards a small amount of mercury bichloride may be added to them. - - - PLATINUM WIRE METHOD.[42] - -This method requires a rod with a platinum wire 1 mm. in diameter -inserted in it about 1 inch from one end of the rod and projecting from -it at a right angle at least 25 mm. Near the other end of the rod, at a -distance of 1.2 meters from the platinum wire, a small ring shall be -placed directly above the wire through which, with his eye directly -above the ring, the observer shall look when making the examination. - -The rod shall be graduated as follows: The graduation mark of 100 shall -be placed on the rod at a distance of 100 mm. from the center of the -wire. Other graduations shall be made according to Table 1, which is -based on the best obtainable data. The distances recorded in Table 1 are -intended to be such that when the water is diluted the turbidity -readings will decrease in the same proportion as the percentage of the -original water in the mixture. These graduations are those on what is -known as the U. S. Geological Survey Turbidity Rod of 1902.[105] - - Table 1.—GRADUATION OF TURBIDITY ROD. - - ───────────────────────────────────┬─────────────────────────────────── - Turbidity │ Vanishing depth of wire (mm.). - (parts per million). │ - │ - ───────────────────────────────────┼─────────────────────────────────── - 7│ 1095 - 8│ 971 - 9│ 873 - 10│ 794 - 11│ 729 - 12│ 674 - 13│ 627 - 14│ 587 - 15│ 551 - 16│ 520 - 17│ 493 - 18│ 468 - 19│ 446 - 20│ 426 - 22│ 391 - 24│ 361 - 26│ 336 - 28│ 314 - 30│ 296 - 35│ 257 - 40│ 228 - 45│ 205 - 50│ 187 - 55│ 171 - 60│ 158 - 65│ 147 - 70│ 138 - 75│ 130 - 80│ 122 - 85│ 116 - 90│ 110 - 95│ 105 - 100│ 100 - 110│ 93 - 120│ 86 - 130│ 81 - 140│ 76 - 150│ 72 - 160│ 68.7 - 180│ 62.4 - 200│ 57.4 - 250│ 49.1 - 300│ 43.2 - 350│ 38.8 - 400│ 35.4 - 500│ 30.9 - 600│ 27.7 - 800│ 23.4 - 1000│ 20.9 - 1500│ 17.1 - 2000│ 14.8 - 3000│ 12.1 - ───────────────────────────────────┴─────────────────────────────────── - -_Procedure._—Lower the rod vertically into the water as far as the wire -can be seen and read the level of the surface of the water on the -graduated scale. This will indicate the turbidity. - -The following precautions shall be taken to insure correct results: - -Observations shall be made in the open air, preferably in the middle of -the day and not in direct sunlight. The wire shall be kept bright and -clean. If for any reason observations cannot be made directly under -natural conditions a pail or tank may be filled with water and the -observation taken in that, but if this is done care shall be taken that -the water is thoroughly stirred before the observation is made, and no -vessel shall be used for this purpose unless its diameter is at least -twice as great as the depth to which the wire is immersed. Waters which -have a turbidity greater than 500 shall be diluted with clear water -before the observations are made, but if this is done the degree of -dilution shall be reported. - - - TURBIDIMETRIC METHOD. - -Several forms of turbidimeter or diaphanometer[73] have been suggested -for use. The simplest and most satisfactory form is the candle -turbidimeter.[116] This consists of a graduated glass tube with a flat -polished bottom, enclosed in a metal case. This is supported over an -English standard candle and so arranged that one may look vertically -down through the tube at the flame of the candle. The observation is -made by pouring the sample of water into the tube until the image of the -flame of the candle just disappears from view. Care shall be taken not -to allow soot or moisture to accumulate on the lower side of the glass -bottom of the tube so as to interfere with the accuracy of the -observations. The graduations on the tube correspond to turbidities -produced in distilled water by certain numbers of parts per million of -silica standard. In order to insure uniform results it is necessary to -have the distance between the top rim of the candle and the bottom of -the tube constant, and this distance shall be 7.6 cm. or 3 inches. The -observations shall be made in a darkened room or with a black cloth over -the head. - -It is allowable to substitute for the candle an electric light. -Calibrate the apparatus to correspond with the United States Geological -Survey scale. The figures in Table 2 on page 8 are believed to be -approximately correct for the candle turbidimeter but should be checked -by the experimenter. It is allowable to calibrate the tube of the -instrument with waters of known turbidity prepared by making a series of -dilutions of the silica standard with distilled water. From the figures -obtained in calibrating plot a curve from which the turbidity of a -sample may be read when the depth of water in the tube has been -obtained. - - Table 2.—GRADUATION OF CANDLE TURBIDIMETER. - - ───────────────────────────────────┬─────────────────────────────────── - Depth of liquid │ Turbidity - (cm.). │ (parts per million of silica). - ───────────────────────────────────┼─────────────────────────────────── - 2.3│ 1000 - 2.6│ 900 - 2.9│ 800 - 3.2│ 700 - 3.5│ 650 - 3.8│ 600 - 4.1│ 550 - 4.5│ 500 - 4.9│ 450 - 5.5│ 400 - 5.6│ 390 - 5.8│ 380 - 5.9│ 370 - 6.1│ 360 - 6.3│ 350 - 6.4│ 340 - 6.6│ 330 - 6.8│ 320 - 7.0│ 310 - 7.3│ 300 - 7.5│ 290 - 7.8│ 280 - 8.1│ 270 - 8.4│ 260 - 8.7│ 250 - 9.1│ 240 - 9.5│ 230 - 9.9│ 220 - 10.3│ 210 - 10.9│ 200 - 11.4│ 190 - 12.0│ 180 - 12.7│ 170 - 13.5│ 160 - 14.4│ 150 - 15.4│ 140 - 16.6│ 130 - 18.0│ 120 - 19.6│ 110 - 21.5│ 100 - ───────────────────────────────────┴─────────────────────────────────── - -The results of turbidity observations shall be expressed in whole -numbers which correspond to parts per million of silica and recorded as -follows: - - Turbidity between │ 1│and│ 50│recorded to nearest│unit - " " │ 51│ " │ 100│ " " " │ 5 - " " │ 101│ " │ 500│ " " " │ 10 - " " │ 501│ " │ 1000│ " " " │ 50 - " " │1001│ " │greater│ " " " │ 100 - - - COEFFICIENT OF FINENESS[80] - -The quotient obtained by dividing the weight of suspended matter in the -sample by the turbidity, both expressed in the same unit, shall be -called the coefficient of fineness. If the quotient is greater than -unity the matter in suspension is coarser and if it is less than unity -it is finer than the standard. - - - COLOR. - -The “color,” or the “true color,” of water shall be considered the color -that is due only to substances in solution; that is, it is the color of -the water after the suspended matter has been removed. In stating -results the word “color” shall mean the “true color” unless otherwise -designated. - -The “apparent color” shall be considered as including not only the true -color but also any color produced by substances in suspension. It is the -color of the original unfiltered sample. - -The platinum-cobalt method of measuring color shall be considered as the -standard, and the unit of color shall be that produced by 1 part per -million of platinum. - - - COMPARISON WITH PLATINUM-COBALT STANDARDS.[43] - -_Reagents._—Dissolve 1.246 grams of potassium platinic chloride -(PtCl_{4}2KCl), containing 0.5 gram platinum, and 1.00 gram crystallized -cobalt chloride (CoCl_{2}.6H_{2}O), containing 0.25 gram of cobalt, in -water with 100 cc. concentrated hydrochloric acid, and dilute to 1 liter -with distilled water. This solution has a color of 500. Dilute this -solution with distilled water in 50 cc. Nessler tubes to prepare -standards having colors of 0, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, and -70. Keep these standards in Nessler tubes of such diameter that the -graduation mark is between 20 and 25 cm. above the bottom and of such -uniformity that they match within such limit that the distance from the -bottom to the graduation mark of the longest tube shall not exceed that -of the shortest tube by more than 6 mm. Protect the tubes from dust and -light when not in use. - -_Procedure._—The color of a sample shall be observed by filling a -standard Nessler tube to the height equal to that in the standard tubes -with the sample and by comparing it with the standards. The observation -shall be made by looking vertically downward through the tubes upon a -white or mirrored surface placed at such angle that light is reflected -upward through the column of liquid. - -Water that has a color greater than 70 shall be diluted before making -the comparison, in order that no difficulties may be encountered in -matching the hues. - -Water containing matter in suspension shall be filtered, before the -color observation is made, until no visible turbidity remains. If the -suspended matter is coarse, filter paper may be used for this purpose; -if the suspended matter is fine, the use of a Berkefeld filter is -recommended. The Pasteur filter shall not be used as it exerts a marked -decolorizing action. - -The apparent color, if determined, shall be determined on the original -sample without filtration. The true and the apparent color of clear -waters or waters with low turbidities are substantially the same. - -The results of color determinations shall be expressed in whole numbers -and recorded as follows: - - Color between 1 and 50 recorded to nearest unit - " " 51 " 100 " " " 5 - " " 101 " 250 " " " 10 - " " 251 " 500 " " " 20. - - - COMPARISON WITH GLASS DISKS.[105] - -As the platinum-cobalt standard method is not well adapted for field -work, the color of the water to be tested may be compared with that of -glass disks held at the end of metallic tubes through which they are -viewed by looking toward a white surface. The glass disks are -individually calibrated to correspond with colors on the platinum scale. -Experience has shown that the glass disks used by the U. S. Geological -Survey give results in substantial agreement with those obtained by the -platinum determinations, and their use is recognized as a standard -procedure. - - - COMPARISON WITH NESSLER STANDARDS. - -Inasmuch as the Nessler scale[62] and the natural water scale[22][49] -which agrees with it except for colors less than 20, have been largely -used in the past, the old results may be converted[117] into terms of -the platinum standard by means of the ratios in Table 3, but they must -not be considered as universally applicable as the variable -sensitiveness of the Nessler solution introduces an uncertain factor. - - Table 3.—VALUES FOR CONVERTING COLORS BY THE NATURAL WATER SCALE INTO - COLORS BY THE PLATINUM STANDARD IN PARTS PER MILLION.[B] - - ───────────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬───── - Modified │ │ │ │ │ │ │ │ │ │ - Nessler or │ │ │ │ │ │ │ │ │ │ - natural │0.00.│0.01.│0.02.│0.03.│0.04.│0.05.│0.06.│0.07.│0.08.│0.09. - water │ │ │ │ │ │ │ │ │ │ - standard. │ │ │ │ │ │ │ │ │ │ - ───────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴───── - Platinum-cobalt standard color. - 0.00│ 0│ 2│ 4│ 6│ 8│ 9│ 11│ 13│ 15│ 17 - .10│ 18│ 19│ 20│ 20│ 21│ 22│ 23│ 24│ 24│ 26 - .20│ 26│ 27│ 27│ 28│ 29│ 29│ 30│ 31│ 32│ 32 - .30│ 33│ 34│ 34│ 35│ 35│ 36│ 37│ 37│ 38│ 38 - .40│ 39│ 40│ 40│ 41│ 42│ 42│ 43│ 44│ 45│ 45 - .50│ 46│ 47│ 47│ 48│ 48│ 49│ 50│ 50│ 51│ 51 - .60│ 52│ 53│ 53│ 54│ 54│ 55│ 56│ 56│ 57│ 57 - .70│ 58│ 58│ 59│ 59│ 60│ 60│ 61│ 61│ 62│ 62 - .80│ 63│ 64│ 64│ 65│ 66│ 66│ 67│ 68│ 69│ 69 - .90│ 70│ 71│ 72│ 73│ 74│ 75│ 77│ 78│ 79│ 80 - 1.00│ 81│ 82│ 82│ 83│ 84│ 84│ 85│ 86│ 87│ 87 - 1.10│ 88│ 89│ 89│ 90│ 91│ 91│ 92│ 93│ 94│ 94 - 1.20│ 95│ 96│ 96│ 97│ 98│ 98│ 99│ 100│ 101│ 101 - 1.30│ 102│ 103│ 103│ 104│ 105│ 105│ 106│ 107│ 108│ 108 - 1.40│ 109│ 110│ 110│ 111│ 112│ 112│ 113│ 114│ 115│ 115 - 1.50│ 116│ 117│ 117│ 118│ 118│ 119│ 120│ 120│ 121│ 121 - 1.60│ 122│ 123│ 123│ 124│ 125│ 125│ 126│ 127│ 128│ 128 - 1.70│ 129│ 130│ 130│ 131│ 132│ 132│ 133│ 134│ 135│ 136 - 1.80│ 136│ 137│ 137│ 138│ 139│ 139│ 140│ 141│ 142│ 142 - 1.90│ 143│ 144│ 144│ 145│ 146│ 146│ 147│ 148│ 149│ 149 - 2.00│ 150│ │ │ │ │ │ │ │ │ - ───────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴───── - -Footnote B: - - Zero on the true Nessler scale is about 15 on the platinum scale. - - - LOVIBOND TINTOMETER. - -The value of the readings of tint and shade by the Lovibond -tintometer[66][82][83] has not been commensurate with the labor -involved, but it is necessary to make a record of the reflected tint and -shade[50] of some waters. The standard color disks used in teaching -optics may be used for the purpose. - -_Procedure._—The white disk supports three movable standard color -sectors, red, yellow, and blue, and one movable black sector. All are -mounted on a device which can be revolved rapidly, blending the colors -into a uniform tint or shade. A scale around the circumference of the -disk is used to indicate the percentage of each color or white or black -in the blend. - -Place the sample in a battery jar on a white ground; adjust the sectors -so that when blended the tint or shade will match the reflected tint or -shade of the sample. Report the percentages of red, yellow blue, white, -and black in the blended tint or shade. - - - ODOR.[4][14][53][72][92][114][115][121c] - -The observation of the odor, cold and hot, of samples of surface water -is important as the odors are usually indicative of organic growths or -sewage contamination or both. The odor of some ground waters is caused -by the earthy constituents of the water-bearing strata. The odor of a -contaminated well water is often contributory evidence of its pollution. -A study of the organisms as directed under Microscopical Examination (p. -90) is a valuable adjunct to physical and chemical examination of water. -Certain odors distinguish or identify certain organisms, as, for -example, the “fishy” odor of _Uroglena_, the “aromatic” or “rose -geranium” odor of _Asterionella_ and the “pig pen” odor of _Anabaena_. -Observe and record the odor, both at room temperature and at just below -the boiling point, as follows: - - - COLD ODOR. - -Shake the sample violently in one of the collecting bottles, when it is -half to two-thirds full and when the sample is at room temperature -(about 20° C.). Remove the stopper and smell the odor at the mouth of -the bottle. - - - HOT ODOR. - -Pour about 150 cc. of the sample into a 500 cc. Erlenmeyer flask. Cover -the flask with a well-fitting watch glass. Heat the water almost to -boiling on a hot plate. Remove the flask from the plate and allow it to -cool not more than five minutes. Then agitate it with a rotary movement, -slip the watch glass to one side, and smell the odor. - - - EXPRESSION OF RESULTS. - -Express the quality of the odor by a descriptive epithet like the -following, which may be abbreviated in the record: - - a—aromatic - C—free chlorine - d—disagreeable - e—earthy - f—fishy - g—grassy - m—moldy - M—musty - P—peaty - s—sweetish - S—hydrogen sulfide - v—vegetable. - -Express the intensity of the odor by a numeral prefixed to the term -expressing quality, which may be defined as follows: - - Numerical Term. Definition. - value. - - 0 None. No odor perceptible. - - 1 Very An odor that would not be detected ordinarily by - faint. the average consumer, but that could be detected - in the laboratory by an experienced observer. - - 2 Faint. An odor that the consumer might detect if his - attention were called to it, but that would not - attract attention otherwise. - - 3 Distinct. An odor that would be detected readily and that - might cause the water to be regarded with - disfavor. - - 4 Decided. An odor that would force itself upon the attention - and that might make the water unpalatable. - - 5 Very An odor of such intensity that the water would be - strong. absolutely unfit to drink. (A term to be used - only in extreme cases.) - - - - - CHEMICAL EXAMINATION. - - - EXPRESSION OF RESULTS. - -The results of chemical analyses shall be expressed in parts per -million, which in most analyses is practically equivalent to milligrams -per liter. In some laboratories other forms of expression have been -used. Results expressed in parts per 100,000 or in grains per gallon may -be transformed to parts per million, or conversely, by the use of the -following table: - - Table 4.—FACTORS FOR TRANSFORMING RESULTS OF ANALYSES. - - ───────────────────────────────┬─────────────────────────────────────── - Unit. │ Equivalent. - ───────────────────────────────┼─────────┬─────────┬─────────┬───────── - │ Grains │ Grains │ │ - │per U.S. │ per │Parts per│Parts per - │ gallon. │Imperial │100,000. │million. - │ │ gallon. │ │ - ───────────────────────────────┼─────────┼─────────┼─────────┼───────── - 1 grain per U. S. gallon │ 1.000│ 1.20│ 1.71│ 17.1 - 1 grain per Imperial gallon │ .835│ 1.00│ 1.43│ 14.3 - 1 part per 100,000 │ .585│ .70│ 1.00│ 10.0 - 1 part per million │ .058│ .07│ .10│ 1.0 - ───────────────────────────────┴─────────┴─────────┴─────────┴───────── - -The following general rules shall govern the use of significant figures -in the expression of results: - -1. If the results show quantities greater than 10 parts per million use -no decimals; record only whole numbers. If the quantities reach hundreds -and thousands of parts record only two significant figures. - -2. If the results are between 1 and 10 parts do not retain more than one -decimal place. - -3. If the results are between 0.1 and 1 part do not retain more than two -decimal places. - -4. Estimates of ammonia, albuminoid, and nitrite nitrogen alone justify -the use of three decimals. - -5. If the results of analyses are tabulated ciphers should not be added -at the right of the decimal point to make the column uniform. - - - FORMS OF NITROGEN. - -Nitrogenous organic matter passes through several intermediate compounds -during its natural decomposition, and that which does not gasify -ultimately forms nitrate. Nitrogen in organic matter is determined by -the Kjeldahl process.[13][14][58] An indication of the amount present is -obtained by the albuminoid nitrogen determination.[14][15][67][106][107] -It has not been found possible to differentiate the nitrogen in the -organic matter that readily decomposes from that in stable or -non-putrescible compounds. Decomposition of organic matter produces -nitrogen combined in ammonia, which is the first step between -nitrogenous organic matter and the completely mineralized nitrate. -Ammonia nitrogen may be determined by distillation and Nesslerization or -by direct Nesslerization of the clarified sample. The next step is -oxidation to nitrite, and the final step, oxidation to nitrate. It is -recommended that all forms of nitrogen be reported as the element -nitrogen (N). - - - AMMONIA NITROGEN. - -There are two methods for estimating ammonia nitrogen—distillation and -direct Nesslerization. Distillation is recommended for most waters and -direct Nesslerization is recommended for sewages, sewage effluents, and -highly polluted surface waters. - - - DETERMINATION BY DISTILLATION.[38][68b][111][121] - -_Procedure._—Use a metal or a glass flask connected with a condenser so -that the distillate may drop from the condenser tube directly into a -Nessler tube or a flask. Free the apparatus from ammonia by boiling -distilled water in it until the distillate shows no trace of ammonia. -After this has been done empty the distilling flask and measure into it -500 cc. of the sample, or a smaller portion diluted to 500 cc. with -ammonia-free water. If the sample is acid or if the presence of urea is -suspected add about 0.5 gram of sodium carbonate before distillation. -Omit this if possible as it tends to increase “bumping.” Apply heat so -that the distillation may proceed at the rate of not more than 10 cc. -nor less than 6 cc. per minute. Collect the distillate in four Nessler -tubes, 50 cc. to each tube, or if the nitrogen is high in a 200 cc. -graduated flask. These receptacles contain the ammonia nitrogen to be -measured as hereafter described. - -Use Nessler tubes of such diameter that the graduation mark is between -20 and 25 cm. above the bottom and of such uniformity of diameter that -the distance from the bottom to the graduation mark of the longest tube -shall not exceed that of the shortest tube by more than 6 mm. The tubes -must be of clear white glass with polished bottoms. - - - MEASUREMENT OF AMMONIA NITROGEN. - -The amount of ammonia in the distillates may be measured either by (1) -comparison of the Nesslerized distillates with Nesslerized solutions -containing known quantities of nitrogen as ammonium chloride, or by (2) -comparison of the Nesslerized distillates with permanent standard -solutions in which the colors of Nesslerized standard ammonia solutions -are duplicated by solutions of platinum and cobalt chlorides. - - - COMPARISON WITH AMMONIA STANDARDS. - -_Reagents._—1. Ammonia-free water. - -2. Standard ammonium chloride solution. Dissolve 3.82 grams of ammonium -chloride in ammonia-free water and dilute to 1 liter; dilute 10 cc. of -this to 1 liter with ammonia-free water. One cc. equals 0.00001 gram of -nitrogen. - -3. Nessler reagent.[8] Dissolve 50 grams of potassium iodide in a -minimum quantity of cold water. Add a saturated solution of mercuric -chloride until a slight precipitate persists permanently. Add 400 cc. of -50 per cent solution of potassium hydroxide, made by dissolving the -potassium hydroxide and allowing it to clarify by sedimentation before -using. Dilute to 1 liter, allow to settle, and decant. This solution -should give the required color with ammonia within five minutes after -addition and should not produce a precipitate with small amounts of -ammonia within two hours. - -_Procedure._—Prepare a series of 16 Nessler tubes containing the -following amounts of the standard ammonium chloride solution, diluted to -50 cc. with ammonia-free water, namely: 0.0, 0.1, 0.3, 0.5, 0.7, 1.0, -1.4, 1.7, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, and 6.0 cc. These solutions -will contain 0.00001 gram of nitrogen for each cubic centimeter of the -standard solution. - -Nesslerize the standards and the distillates by adding approximately 1 -cc. of Nessler reagent to each tube. Do not stir the contents of the -tubes. The temperature of the tubes should be practically the same as -that of the standards; otherwise the colors will not be directly -comparable.[45] Allow the tubes to stand at least 10 minutes after -Nesslerizing. Compare the color produced in the tubes with that in the -standards by looking vertically downward through them at a white or -mirrored surface placed at an angle in front of a window so as to -reflect the light upward. - -If the color obtained by Nesslerizing the distillates is greater than -that of the darkest tube of the standards, mix the contents of the tube -thoroughly, pour out half of the liquid, and dilute the remainder to the -original volume with ammonia-free water; then make the color comparison -and multiply the result by two. If the color is still too dark after -pouring out half the liquid, repeat this process of division until a -reading can be made. The process of dilution may be shortened by mixing -together the distillates from one sample before making the comparison -and comparing an aliquot portion with the standards. - -After the readings have been recorded add the results obtained by -Nesslerizing each portion of the entire distillate. If 500 cc. of the -sample is distilled this sum, expressed in cubic centimeters and -multiplied by 0.02, will give the number of parts per million of ammonia -nitrogen in the sample. If x cc. of sample is used multiply the sum of -the readings by 10/x. - -If the ammonia is known to be high the distillate may be collected in -200 cc. flasks and an aliquot part Nesslerized. - - - COMPARISON WITH PERMANENT STANDARDS.[62][65] - -_Reagents._—Platinum solution. Dissolve 2.00 grams of potassium platinic -chloride (PtCl_{4}.2KCl) in a small amount of distilled water, add 100 -cc. of strong hydrochloric acid, and dilute to 1 liter. - -Cobalt solution. Dissolve 12 grams of cobaltous chloride -(CoCl_{2}.6H_{2}O) in distilled water, add 100 cc. of strong -hydrochloric acid, and dilute to 1 liter. - -Prepare standards by putting various amounts of these two solutions into -Nessler tubes and diluting to the 50 cc. mark with distilled water as -indicated in Table 5. These standards may be kept for several months if -protected from dust. - - Table 5.—PREPARATION OF PERMANENT STANDARDS FOR THE DETERMINATION OF - AMMONIA. - - ───────────────────────┬───────────────────────┬─────────────────────── - Value in standard │ Solution of platinum. │ Solution of cobalt. - ammonium chloride. │ │ - ───────────────────────┼───────────────────────┼─────────────────────── - _cc._│ _cc._│ _cc._ - 0.0│ 1.2│ 0.0 - .1│ 1.8│ .0 - .2│ 2.8│ .0 - .4│ 4.7│ .1 - .7│ 5.9│ .2 - │ │ - 1.0│ 7.7│ .5 - 1.4│ 9.9│ 1.1 - 1.7│ 11.4│ 1.7 - 2.0│ 12.7│ 2.2 - 2.5│ 15.0│ 3.3 - │ │ - 3.0│ 17.3│ 4.5 - 3.5│ 19.0│ 5.7 - 4.0│ 19.7│ 7.1 - 4.5│ 19.9│ 8.7 - 5.0│ 20.0│ 10.4 - │ │ - 6.0│ 20.0│ 15.0 - 7.0│ 20.0│ 22.0 - ───────────────────────┴───────────────────────┴─────────────────────── - -The amounts in Table 5 are approximate, and the actual amount necessary -will differ with the character of the Nessler solution, the color -sensitiveness of the analyst’s eye, and other conditions. The final test -of the standard is best obtained by comparing it with Nesslerized -standards and modifying the tint accordingly. Such comparison should be -made for each new batch of Nessler solution and should be checked by -each analyst. - -_Procedure._—In comparison with permanent standards, Nesslerize the -distillates in the manner above described and compare the resulting -colors at the end of about 10 minutes with the permanent standards. The -method of calculating results is precisely the same as with the ammonia -standards. - - - MODIFICATION FOR SEWAGE. - -Ammonia nitrogen and albuminoid nitrogen in sewages, soils, and other -materials of high nitrogen content may be satisfactorily determined by -diluting the sample with ammonia-free distilled water and proceeding as -described in the preceding sections, but it is permissible to distill -with steam.[40] - -_Procedure._—Use a 200 cc. long-necked Kjeldahl flask connected with a -condenser so that the distillate may drop from the condenser tube -directly into a Nessler tube or a flask. Connect the Kjeldahl flask with -a steam generator by a tube reaching almost to the bottom of the flask. - -After the apparatus is freed from ammonia put the sample to be tested -into the flask. Use 10 to 100 cc. of the sample according to its ammonia -content. Pass ammonia-free steam through the liquid in the Kjeldahl -flask and collect the distillate in the usual way. It is usually -convenient to collect the distillate in a 200 cc. flask and to take an -aliquot part of it for Nesslerization. Compare with standards and -calculate the nitrogen content in the usual manner. - -This method has the advantage, when the sample is treated with an -alkaline solution of potassium permanganate, of avoiding bumping, -permitting the assay of solid matter, and yielding the ammonia more -rapidly than by the ordinary process of distillation. - - - DETERMINATION BY DIRECT NESSLERIZATION.[21][75] - - _Reagents._— 1. Ten per cent solution of copper sulfate - (CuSO_{4}.5H_{2}O). - - 2. Ten per cent solution of lead acetate - (Pb(C_{2}H_{3}O_{2})_{2}.3H_{2}O). - - 3. Fifty per cent solution of sodium hydroxide (NaOH) or - potassium hydroxide (KOH). - -_Procedure._—To 50 cc. of the sample to be tested, diluted if necessary -with an equal volume of ammonia-free water, in a short tube, add a few -drops of the copper sulfate solution. After thoroughly mixing, add 1 cc. -of the alkali hydroxide solution and again thoroughly mix. Allow the -tube to stand for a few minutes, when a heavy precipitate should fall to -the bottom, leaving a colorless supernatant liquid. Nesslerize an -aliquot part. Compare with standards and compute the ammonia nitrogen in -the same manner as in the distillation procedure. - -Samples containing hydrogen sulfide may require the use of lead acetate -in addition to the copper sulfate. Some samples may require a few trials -before the right combination of the three solutions to bring about the -best results can be found. - -Instead of adding copper sulfate to sewages of high magnesium content -satisfactory clarification of the sample can be obtained by mixing it -with the alkali hydroxide alone.[54] - - - ALBUMINOID NITROGEN. - -The addition of an alkaline permanganate solution to liquids containing -nitrogenous organic matter causes the formation of ammonia, which can be -distilled and determined by Nesslerization of the distillate. The -nitrogen of the ammonia, thus obtained, is called albuminoid nitrogen. -As the ratio of nitrogenous organic matter to the ammonia obtained by -distillation is decidedly variable[6][30][75] in sewages and other -substances containing much nitrogenous organic matter albuminoid -nitrogen results on such substances are less accurate[29] than organic -(Kjeldahl) nitrogen. Therefore in sewage work, including analysis of -influents and effluents of purification plants and the water of highly -polluted streams, it is recommended that determinations of organic -nitrogen be substituted for determinations of albuminoid nitrogen. For -ground waters and surface waters containing but little pollution, the -albuminoid nitrogen is approximately one-half the organic nitrogen; -accordingly the continuance of albuminoid nitrogen determinations for -this class of work is approved. - -_Reagents._—Alkaline potassium permanganate. Pour 1,200 cc. of distilled -water into a porcelain dish holding 2,500 cc., boil 10 minutes, and turn -off the gas. Add 16 grams of C. P. potassium permanganate and stir until -solution is complete. Then add 800 cc. of 50 per cent clarified solution -of potassium hydroxide or an equivalent amount of sodium hydroxide and -enough distilled water to fill the dish. Boil down to 2,000 cc. Test -this solution for ammonia by making a blank determination. Correct -determinations by the amount of this blank. - -_Procedure._—After the collection of the distillate for ammonia nitrogen -described on page 15 add 50 cc. (or more if necessary to insure the -complete oxidation of the organic matter) of alkaline potassium -permanganate and continue the distillation until at least four portions, -and preferably five portions, of 50 cc. each, of distillate have been -collected in separate tubes. Determine the albuminoid nitrogen in the -distillate by Nesslerization. If the albuminoid nitrogen is known to be -high it is convenient to collect the distillate in a 200 cc. flask and -to Nesslerize an aliquot part of it. - -Dissolved albuminoid nitrogen may be determined in a sample from which -suspended matter has been removed by filtration either through filter -paper or through a Berkefeld filter. Suspended albuminoid nitrogen is -the difference between the total and the dissolved albuminoid nitrogen. - - - ORGANIC NITROGEN.[24b][69][71][76][84] - -_Procedure for water._—Boil 500 cc. of the sample in a round-bottomed -flask to remove ammonia nitrogen. This usually causes the loss of 200 -cc. of the sample, which may be collected for the determination of -ammonia nitrogen. Add 5 cc. of nitrogen-free concentrated sulfuric acid -and a small piece of ignited pumice. Mix by shaking and place over a -flame under a hood. Digest until copious fumes of sulfuric acid are -given off and the liquid finally becomes colorless or pale straw color. -Remove from the flame, and add potassium permanganate crystals in small -portions until a heavy green precipitate persists in the liquid. Cool. -Dilute to about 300 cc. with ammonia-free water. Make alkaline with 10 -per cent ammonia-free sodium hydroxide. Distill the ammonia, collect the -distillate in Nessler tubes, Nesslerize, and compare with standards as -described (pp. 16–18). - -_First procedure for sewage_[76].—Distill the ammonia nitrogen directly -from 100 cc. or less of the sample, diluted to 500 cc. with -nitrogen-free water. Collect the distillate and determine the ammonia -nitrogen in it. Add 5 cc. of nitrogen-free sulfuric acid and 1 cc. of 10 -per cent nitrogen-free copper sulfate, and digest the liquid for half an -hour after it has become colorless or pale straw color. Add 0.5 gram of -potassium permanganate crystals to the hot acid solution, and dilute to -500 cc. with ammonia-free water. Dilute 10 cc. or more of this liquid, -in a Kjeldahl distilling flask, to about 300 cc. with ammonia-free -water. Make alkaline with 10 per cent sodium hydroxide, distill, and -Nesslerize. With some samples direct Nesslerization may be used. (See p. -19.) - -In this determination care must be taken to digest thoroughly, to add -potassium permanganate to the point of precipitation, to sample -carefully after dilution, and to add enough sodium hydroxide to insure -the separation of the ammonia from the precipitated manganese hydroxide. -Potassium permanganate should not be added during digestion because it -causes loss of nitrogen. - -_Second procedure for sewage._—Omit the separation of ammonia nitrogen -and determine the ammonia nitrogen and organic nitrogen together. -Determine the ammonia nitrogen in a separate sample by direct -Nesslerization as described on page 19. The organic nitrogen is equal to -the difference. - - - NITRITE NITROGEN.[51][63a][64][94c][108] - -_Reagents._—1. Sulfanilic acid solution. Dissolve 8.00 grams of the -purest sulfanilic acid in 1,000 cc. of 5 N acetic acid (sp. gr. 1.041) -or in 1,000 cc. of water containing 50 cc. of concentrated hydrochloric -acid. This is practically a saturated solution. - -2. α-naphthylamine acetate or chloride solution. Dissolve 5.00 grams -solid α-naphthylamine in 1,000 cc. of 5 N acetic acid or in 1,000 cc. of -water containing 8 cc. of concentrated hydrochloric acid. Filter the -solution through washed absorbent cotton or an alundum filter. - -3. Sodium nitrite stock solution. Dissolve 1.1 gram silver nitrite in -nitrite-free water; precipitate the silver with sodium chloride solution -and dilute the whole to 1 liter. - -4. Standard sodium nitrite solution. Dilute 100 cc. of solution 3 to 1 -liter, then dilute 50 cc. of this solution to 1 liter with sterilized -nitrite-free water, add 1 cc. of chloroform, and preserve in a -sterilized bottle. One cc. = 0.0005 mg. nitrogen. - -5. Fuchsine solution. 0.1 gram per liter. - -_Procedure._—Place in a standard Nessler tube 50 cc. of the sample, -decolorized if necessary with nitrite-free aluminium hydroxide (see p. -42) or a smaller amount diluted to 50 cc. At the same time prepare in -Nessler tubes a set of standards, by diluting to 50 cc. with -nitrite-free water, various amounts of the standard nitrite solution. -The following amounts of standard solution are suggested: 0.0, 0.1, 0.2, -0.4, 0.7, 1.0, 1.4, 1.7, 2.0, and 2.5 cc. Add 1 cc. of the sulfanilic -acid solution and 1 cc. of the α-naphthylamine acetate or hydrochloride -solution to the sample and to each standard. Mix thoroughly and allow to -stand 10 minutes; then compare the sample with the standards. Do not -allow the sample to stand more than one-half hour before making the -comparison. If the color of the sample is deeper than that of the -highest standard repeat the test on a diluted sample. If 50 cc. of the -sample is used 0.01 times the number of cc. of the standard matched -equals parts per million of nitrite nitrogen. Satisfactory results can -be obtained by using either hydrochloric or acetic acid in preparing the -test solutions, but the speed of the reaction is more rapid if acetic -acid is used.[112] - -Permanent standards may be prepared by matching the nitrite standards -with dilutions of the fuchsine solution. Fuchsine standards have been -found to be sufficiently accurate for waters high in nitrite and for -sewage. The standards should be checked once a month and kept out of -bright sunlight. - - - NITRATE NITROGEN.[16][36][90][100] - -Two methods are recommended for the determination of nitrate nitrogen in -water, sewage, and sewage effluents. - - - PHENOLDISULFONIC ACID METHOD.[1][5][32] - -_Reagents._—1. Phenoldisulfonic acid. Dissolve 25 grams of pure white -phenol in 150 cc. of pure concentrated sulfuric acid. Add 75 cc. of -fuming sulfuric acid (15 per cent SO_{3}), stir well, and heat for 2 -hours at about 100°C. - -2. Potassium hydroxide solution. Prepare an approximately 12 N solution, -10 cc. of which will neutralize about 4 cc. of the phenoldisulfonic -acid. - -3. Standard nitrate solution. Dissolve 0.72 gram of pure recrystallized -potassium nitrate in 1 liter of distilled water. Evaporate cautiously to -dryness 10 cc. of the solution on the water bath. Moisten residue -quickly and thoroughly with 2 cc. of phenoldisulfonic acid and dilute to -1 liter. This is the standard solution, 1 cc. of which equals 0.001 mg. -of nitrate nitrogen. - -4. Standard silver sulfate solution. Dissolve 4.4 grams of silver -sulfate free from nitrate in 1 liter of water. One cc. of this solution -is equal to 1 mg. of chloride. - -_Procedure._—The alkalinity, chloride, and nitrite content, and color of -the sample must first be determined. If the sample is highly colored -decolorize it with freshly precipitated aluminium hydroxide. Measure -into an evaporating dish 100 cc. of the sample, or if nitrate is very -high such volume as will contain about 0.01 mg. of nitrate nitrogen. Add -sufficient N/50 sulfuric acid nearly to neutralize the alkalinity. Then -add sufficient standard silver sulfate to precipitate all but about 0.1 -mg. of chloride. The removal of chloride may be omitted if the sample -contains less than 30 parts per million of chloride. Heat the mixture to -boiling, add a little aluminium hydroxide, stir, filter, and wash with -small amounts of hot water. Evaporate the filtrate to dryness, and add 2 -cc. of the phenoldisulfonic acid, rubbing with a glass rod to insure -intimate contact. If the residue becomes packed or appears vitreous -because of the presence of much iron, heat the dish on the water bath -for a few minutes. Dilute the mixture with distilled water, and add -slowly a strong solution of potassium hydroxide or ammonium hydroxide -until the maximum color is developed. Transfer the solution to a Nessler -tube, filtering if necessary. If nitrate is present a yellow color will -be formed. Compare the color with that of standards[52][55] made by -adding 2 cc. of strong potassium hydroxide or ammonium hydroxide to -various amounts of standard nitrate solution and diluting them to 50 cc. -in Nessler tubes. The following amounts of standard nitrate solution are -suggested: 0, 0.5, 1.0, 1.5, 2.0, 4.0, 6.0, 8.0, 10.0, 15.0, 20.0, and -40.0 cc. These standards may be kept several weeks without -deterioration. If 100 cc. of water is used the number of cubic -centimeters of the standard multiplied by 0.01 is equal to parts per -million of nitrate nitrogen. - -Standards that will remain permanent for several years if stored in the -dark may be prepared from tripotassium nitrophenoldisulfonate.[5] - -If nitrite nitrogen is present in excess of 1 part per million it should -be oxidized by heating the samples a few minutes with a few drops of -hydrogen peroxide free from nitrate repeatedly added[95] or by adding -dilute potassium permanganate in the cold until a faint pink coloration -appears; the nitrogen equivalent of the nitrite thus oxidized to nitrate -is then subtracted from the final nitrate nitrogen reading. - - - REDUCTION METHOD.[2][46] - -_Reagents._—1. Sodium or potassium hydroxide solution. Dissolve 250 -grams of the hydroxide in 1.25 liters of distilled water. Add several -strips of aluminium foil and allow the evolution of hydrogen to continue -over night. Concentrate the solution to 1 liter by boiling. - -2. Aluminium foil. Use strips of pure aluminium about 10 cm. long, 6 mm. -wide, and 0.33 mm. thick and weighing about 0.5 gram. - -_Procedure._—To 100 cc. of the sample in a 300 cc. casserole add 2 cc. -of the hydroxide solution and concentrate by boiling to about 20 cc. -Pour the contents of the casserole into a test tube about 16 cm. long -and 3 cm. in diameter, or of approximately 100 cc. capacity. Rinse the -casserole several times with nitrogen-free water and add the rinse water -to the liquid already in the tube, thus making the contents of the tube -approximately 75 cc. Add a strip of aluminium foil. Close the tube by -means of a rubber stopper through which passes a bent glass tube about 5 -mm. in diameter. Put the shorter arm of the tube flush with the lower -side of the rubber stopper and let the longer arm extend below the -surface of distilled water in another test tube. This apparatus serves -as a trap through which the evolved hydrogen escapes freely. The small -amount of ammonia escaping into the trap may be neglected. Allow the -action to proceed for a minimum period of four hours or over night. Pour -the contents of the tube into a distilling flask, dilute with 250 cc. of -ammonia-free water, distill, collect the distillate in Nessler tubes, -and Nesslerize. If the nitrate content is high collect the distillate in -a 200 cc. flask and Nesslerize an aliquot part. If the supernatant -liquid in the reduction tube is clear and colorless the solution may be -diluted to a definite volume and an aliquot part Nesslerized without -distillation. - - - TOTAL NITROGEN.[93] - -In sewage work it is frequently of assistance to know the total nitrogen -content. This is ordinarily computed by adding together the organic, -ammonia, nitrite, and nitrate nitrogen, each of which is determined as -already described. - - - OXYGEN CONSUMED.[24][67][84a][85][94f][101][102] - -Oxygen consumed means the oxygen that the oxidizable compounds of sewage -and water consume when treated in an acid solution with potassium -permanganate. The expression is synonymous with oxygen required, oxygen -absorbed, and oxygen-consuming capacity. It should not be confused with -biochemical oxygen demand. - -As the carbon, not the nitrogen, in organic matter is oxidized by -potassium permanganate, oxygen consumed is considered by some an -indication of the amount of carbonaceous organic matter present. The -determination indicates, however, only part of the carbon, the -proportion varying in different samples because the carbon in -nitrogenous matter is not so readily oxidized as that in carbonaceous -organic matter. Furthermore, it does not directly differentiate the -carbon present in unstable organic matter from that in fairly stable -organic matter, such as is sometimes referred to as residual humus -matter. As nitrite nitrogen, ferrous iron, sulfide, and other oxidizable -mineral substances reduce potassium permanganate, corrections for them -should be made in the determination. - - - RECOMMENDED METHOD. - -_Reagents._—1. Dilute sulfuric acid. Dilute 1 part of concentrated -sulfuric acid with 3 parts of distilled water and free the solution from -oxidizable matter by adding potassium permanganate until a faint pink -color persists after the solution has stood several hours. - -2. Standard ammonium oxalate. Dissolve 0.888 gram of the pure salt in 1 -liter of distilled water. One cc. is equivalent to 0.1 mg. of oxygen. An -equivalent quantity of oxalic acid or sodium oxalate may be used. - -3. Standard potassium permanganate. Dissolve 0.4 gram of the -crystallized salt in 1 liter of distilled water. Add 10 cc. of the -dilute sulfuric acid and 10 cc. of this solution of potassium -permanganate to 100 cc. of distilled water, and digest 30 minutes. Add -10 cc. of the ammonium oxalate solution, and then add potassium -permanganate till a pink coloration appears. This destroys the -oxygen-consuming capacity of the water used. Now add another 10 cc. of -ammonium oxalate solution and titrate with potassium permanganate. -Adjust the potassium permanganate solution so that 1 cc. is equivalent -to 1 cc. of ammonium oxalate solution or 0.1 mg. of available oxygen. - -_Acid digestion._—Place in a flask 100 cc. of the water, or, if the -water is of high organic content, a smaller portion diluted to 100 cc. -Add 10 cc. of sulfuric acid solution and 10 cc. of standard potassium -permanganate and digest the liquid exactly 30 minutes in a bath of -boiling water the level of which is kept above the level of the contents -of the flask.[70][71a] If the quantity of permanganate is insufficient -for complete oxidation repeat the digestion with a larger quantity; at -least 5 cc. excess of the standard permanganate should be present when -the ammonium oxalate solution is added. Remove the flask, add 10 cc. of -the ammonium oxalate solution, and titrate with the standard -permanganate until a faint but distinct color is obtained. If 100 cc. of -water is used the number of cubic centimeters of potassium permanganate -solution in excess of the number of cubic centimeters of ammonium -oxalate solution is equal to parts per million of oxygen consumed. - -If oxidizable mineral substances, such as ferrous iron, sulfide, or -nitrite, are present in the sample corrections should be applied as -accurately as possible by suitable procedures. Direct titration of the -acidified sample in the cold, using a three-minute period of digestion, -serves this purpose quite well for polluted surface waters and fairly -well for purified sewage effluents. Few raw sewages containing no trade -wastes need such a correction, but raw sewages containing “pickling” -liquors do need it. If the sample contains both oxidizable mineral -compounds and gaseous organic substances the latter should be driven off -by heat and the sample allowed to cool before applying this test for the -correction factor. If such corrections are made the fact should be -stated with the amount of correction. - -_Period and temperature of digestion._—As the practice in regard to the -period and temperature of digestion has varied widely it is difficult to -compare the results obtained at one laboratory with those obtained at -another. None of the methods gives absolute results. They are all -relative[26][29][57] at best. Digesting 30 minutes at the boiling -temperature is herein designated the recommended method. If samples are -analyzed by any other method the method should be noted, and, -representative results by the standard method should be placed on record -for purposes of comparison. - - - OTHER METHODS. - -_Additional reagents._—1. Potassium iodide solution. Ten per cent -solution, free from iodate. - -2. Standard sodium thiosulfate. Dissolve 1.0 gram of the pure -crystallized salt in 1 liter of distilled water. Standardize this -solution against the standard potassium permanganate. As the thiosulfate -solution does not keep well determine its actual strength at frequent -intervals. - -3. Starch indicator. Prepare as directed in the section on dissolved -oxygen (pp. 65–66). - -4. Sodium hydroxide solution. Dissolve 1 part of pure sodium hydroxide -in 2 parts of distilled water. - -Certain widely practiced deviations from the standard procedure just -described are noted in the following paragraphs. - -1. Heat the acidified sample to boiling, add the permanganate solution, -and digest for two minutes[16] at boiling temperature. This procedure is -facilitated by agitating the liquid constantly with a small current of -air to guard against bumping. - -2. Same method as No. 1 except that the period of digestion is five -minutes.[121a] - -3. Same method as No. 2 except that the permanganate solution is added -to the acidified sample when cold, and digestion is continued five -minutes after the sample reaches the boiling point. The advantage of -this method is that there is included the oxygen-consuming power of the -volatile matter present in some sewages and sewage effluents, which is -driven off by heat and thus escapes when the test is made in accordance -with procedures 1 and 2. - -4. Same method as No. 3 except that the period of digestion is 10 -minutes.[63][68c] - -5. Digestion of the sample after the acid and permanganate solutions are -added is carried out abroad, especially in England, at approximately the -room temperature,[24a][69a][94f][100a] apparently to guard against -decomposition[17] of permanganate in the presence of high chloride, for -periods of three minutes, fifteen minutes, and four hours; many -observers record the oxygen consumed after all three periods, while some -record the result only for the four-hour period. At the end of the -period of digestion, add 0.5 cc. of potassium iodide solution to -discharge the pink color; mix; titrate the liberated iodine with -thiosulfate until the yellow color is nearly destroyed, then add a few -drops of starch solution and continue titration until the blue color is -just discharged. The number of cubic centimeters of potassium -permanganate solution in excess of the number of cubic centimeters of -sodium thiosulfate solution is equal to parts per million of oxygen -consumed. - -6. Digestion in alkaline solution[104] is preferable to digestion in -acid solution for brines or waters high in chlorine. Place in a flask -100 cc. of the sample, or if it is of high organic content a smaller -portion diluted to 100 cc. Add 0.5 cc. of sodium hydroxide solution and -10 cc. of standard potassium permanganate and digest exactly 30 minutes. -Remove the flask, add 5 cc. of sulfuric acid and 10 cc. of the standard -ammonium oxalate, and titrate with the standard potassium permanganate -as in the acid digestion. - - - RESIDUE ON EVAPORATION. - - - TOTAL RESIDUE.[16] - -Ignite and weigh a clean platinum dish, and measure into it 100 cc. of -the thoroughly shaken sample. Evaporate to dryness on a water bath. Then -heat the dish in an oven at 103° C. or 180° C. for one hour. Cool in a -desiccator and weigh. The temperature of drying should be mentioned in -the report. The increase in weight gives the total solids or residue on -evaporation. If 100 cc. of the sample was taken this weight expressed in -milligrams and multiplied by 10 is equal to parts per million of residue -on evaporation. The residue from waters low in organic matter but -relatively high in iron may be used, as a matter of convenience, for the -determination of iron. - - - FIXED RESIDUE AND LOSS ON IGNITION.[13][96] - -The residue from sewages and waters high in organic matter may be -ignited to burn off the organic matter, which, with some volatile -inorganic matter, constitutes the loss on ignition. - -_Procedure._—Ignite the residue in the platinum dish at a low red heat. -If great accuracy is desired this should be done in an electric muffle -furnace or in a radiator, which consists of a platinum or a nickel dish -large enough to allow an air space of about half an inch between it and -the dish within it, the inner dish being supported by a triangle of -platinum wire laid on the bottom of the outer dish. A disc of platinum -or nickel foil large enough to cover the outer dish is suspended over -the inner dish to radiate the heat into it. The larger dish is heated to -bright redness until the residue is white or nearly so. Allow the dish -to cool, and moisten the residue with a few drops of distilled water. -Dry the residue in the oven, cool in a desiccator, and weigh. The fixed -residue on evaporation is the difference between this weight and the -weight of the dish. - -The loss on ignition is the difference between the total residue on -evaporation and the fixed residue on evaporation. - -If the odor and color on ignition of some residues give helpful clues to -the character of the organic matter record them. - - - SUSPENDED MATTER.[56][110] - - - DETERMINATION WITH GOOCH CRUCIBLE. - -_Reagent._—Prepare a dilute cream of asbestos fibre which has been -finely shredded, thoroughly ignited, treated with strong hydrochloric -acid for at least 12 hours, and washed with distilled water till free -from acid. - -_Procedure._—1. Prepare a mat of the asbestos fibre 1/16 inch thick in a -Gooch crucible. Dry it in an oven at 103 or 180° C., cool and weigh. -Filter 1,000 cc. of samples having a turbidity of 50 parts per million -or less. If the turbidity is higher use sufficient water to obtain 50 to -100 mg. of suspended matter. Dry for one hour at 103 or 180° C., cool -and weigh. Report the temperature at which the residue was dried. If -1,000 cc. is filtered the increase in weight expressed in milligrams is -equal to parts per million of suspended matter. - - - DETERMINATION BY FILTRATION. - -The difference between the total solids in filtered and unfiltered -portions of a sample may be used as a basis for calculating suspended -matter. - - - DETERMINATION OF VOLUME. - -The determination of the volume[9][69b] of suspended matter in sewages -has received considerable attention abroad. Imhoff recommends the use of -conical glass vessels holding 1 liter with the lower portions graduated -in cubic centimeters. Others recommend centrifuges with sediment tubes. - - - FIXED RESIDUE AND LOSS ON IGNITION. - -Treat the total residue from a filtered sample in the same manner as -described for the total residue, and obtain the loss on ignition due to -dissolved matter, and by difference the loss on ignition due to -suspended matter. - - - HARDNESS.[94e] - -A water containing certain mineral constituents in solution, chiefly -calcium and magnesium, which form insoluble compounds with soap, is said -to be hard. Carbon dioxide in water increases the solubility of calcium -and magnesium carbonates, forming bicarbonate. If carbon dioxide is -removed from the water by boiling the bicarbonate is decomposed and -calcium and magnesium are partly precipitated. The proportion of calcium -or magnesium carbonate that a water can hold in solution depends on the -concentration of carbon dioxide, which in turn depends on the -temperature of the water and the proportion of carbon dioxide in the -atmosphere with which the water has been in contact. Consequently, when -the carbon dioxide is removed from the water by boiling or otherwise the -carbonates of calcium and magnesium are partly, but not completely, -precipitated, and the hardness of the water is thus diminished and the -water is softened to the extent to which these substances are -precipitated. The hardness thus removed is called temporary hardness. -The hardness which still remains after boiling is due mainly to calcium -and magnesium in equilibrium with sulfate, chloride, and nitrate, and -residual carbonate, and it is called permanent hardness. Non-carbonate -hardness is the hardness caused by sulfates, chlorides, and nitrates of -calcium, magnesium, iron, and other metals that form insoluble soaps. - - - TOTAL HARDNESS BY CALCULATION. - -The most accurate method of ascertaining total hardness is to compute it -from the results of determinations of calcium and magnesium in the -sample. (See methods, pp. 57–58.) Iron and other metals must be included -in the calculation if they are present in significant amounts. Total -hardness as CaCO_{3} equals 2.5 Ca plus 4.1 Mg. - - - TOTAL HARDNESS BY SOAP METHOD.[121b] - -The determination of hardness by the soap method roughly approximates -the amount of calcium and magnesium in a water, though it actually -measures the soap-consuming power of the water. - -_Reagents._—1. Standard calcium chloride solution. Dissolve 0.2 gram of -pure calcite (calcium carbonate) in a little dilute hydrochloric acid, -being careful to avoid loss of solution by spattering. Evaporate the -solution to dryness several times with distilled water to expel excess -of acid. Dissolve the residue in distilled water and dilute the solution -to 1 liter. One cc. of this dilution is equivalent to 0.2 mg. of calcium -carbonate. - -2. Standard soap solution. Dissolve 100 grams of dry white Castile soap -in 1 liter of 80 per cent alcohol, and allow this solution to stand -several days before standardizing. Pure potassium oleate made from lead -plaster and potassium carbonate may be used in place of Castile soap. - -_First method of standardization._—Dilute 20 cc. of the calcium chloride -solution in a 250 cc. glass-stoppered bottle to 50 cc. with distilled -water which has been recently boiled and cooled. Add soap solution from -a burette, 0.2 or 0.3 cc. at a time, shaking the bottle vigorously after -each addition until a lather remains unbroken for five minutes over the -entire surface of the water while the bottle lies on its side. Then -adjust the strength of the stock solution with 70 per cent alcohol so -that the resulting diluted soap solution will give a permanent lather -when 6.40 cc. of it is properly added to 20 cc. of standard calcium -chloride solution diluted to 50 cc. Usually 75 to 100 cc. of the stock -soap solution is required to make 1 liter of the standard soap solution. -The quantity of calcium carbonate equivalent to each cubic centimeter of -the standard soap solution consumed in the titration is indicated in -Table 6. - - Table 6.—TOTAL HARDNESS IN PARTS PER MILLION OF CaCO_{3} FOR EACH TENTH - OF A CUBIC CENTIMETER OF SOAP SOLUTION WHEN 50 CC. OF THE SAMPLE IS - TITRATED. - - ───────────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬───── - Cubic │ │ │ │ │ │ │ │ │ │ - centimeters│ 0.0.│ 0.1.│ 0.2.│ 0.3.│ 0.4.│ 0.5.│ 0.6.│ 0.7.│ 0.8.│ 0.9. - of soap │ │ │ │ │ │ │ │ │ │ - solution. │ │ │ │ │ │ │ │ │ │ - ───────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼───── - 0.0│ │ │ │ │ │ │ │ 0.0│ 1.6│ 3.2 - 1.0│ 4.8│ 6.3│ 7.9│ 9.5│ 11.1│ 12.7│ 14.3│ 15.6│ 16.9│ 18.2 - 2.0│ 19.5│ 20.8│ 22.1│ 23.4│ 24.7│ 26.0│ 27.3│ 28.6│ 29.9│ 31.2 - │ │ │ │ │ │ │ │ │ │ - 3.0│ 32.5│ 33.8│ 35.1│ 36.4│ 37.7│ 38.0│ 40.3│ 41.6│ 42.9│ 44.3 - 4.0│ 45.7│ 47.1│ 48.6│ 50.0│ 51.4│ 52.9│ 54.3│ 55.7│ 57.1│ 58.6 - 5.0│ 60.0│ 61.4│ 62.9│ 64.3│ 65.7│ 67.1│ 68.6│ 70.0│ 71.4│ 72.9 - │ │ │ │ │ │ │ │ │ │ - 6.0│ 74.3│ 75.7│ 77.1│ 78.6│ 80.0│ 81.4│ 82.9│ 84.3│ 85.7│ 87.1 - 7.0│ 88.6│ 90.0│ 91.4│ 92.9│ 94.3│ 95.7│ 97.1│ 98.6│100.0│101.5 - ───────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴───── - -This table does not provide for the use of so large volume of soap -solution for a single determination as former ones because the end-point -becomes somewhat obscured in the presence of magnesium if more than 7 -cc. is used. - -_Second method of standardization._—Dilute 100 cc. of the stock soap -solution to 1 liter with 70 per cent alcohol. This dilute solution -should be of such strength that approximately 6.4 cc. of it will give a -permanent lather when 20 cc. of standard calcium chloride solution -diluted to 50 cc. with distilled water is titrated with it. Determine -the amount of soap solution required to give a permanent lather with 50 -cc. of distilled water and with 5, 10, 15, and 20 cc. of standard -calcium chloride solution diluted to 50 cc. with distilled water. -Finally plot on cross-section paper a curve showing the relation of -various quantities of soap solution to corresponding quantities of -standard calcium carbonate solution and therefore to parts per million -of hardness. - -_Procedure._—Measure 50 cc. of the water into a 250 cc. bottle and add -to it soap solution in small quantities in precisely the same manner as -described under the standardization of the soap solution. From the -number of cubic centimeters of soap solution used obtain from Table 6 or -from the plotted curve the total hardness of the water in parts per -million of calcium carbonate. - -To avoid mistaking the false or magnesium end-point for the true one[35] -when adding the soap solution to waters containing magnesium salts, read -the burette after the titration is apparently finished, and add about -0.5 cc. more of soap solution. If the end-point was due to magnesium the -lather will disappear. Soap solution must then be added until the true -end-point is reached. Usually the false lather persists for less than -five minutes. - -If more than 7 cc. of soap solution is required for 50 cc. of the water -take less of the sample and dilute it to 50 cc. with distilled water -which has been recently boiled and cooled. This step reduces somewhat -the disturbing influence of magnesium,[107a] which consumes more soap -than an equivalent weight of calcium. - -At best the soap method is not a precise test on account of the -different relative amounts of calcium and magnesium in different waters. -For hard waters, especially in connection with processes for -purification and softening, it is advised that this method be not -exclusively used. If the same water is frequently analyzed it may be of -assistance to standardize the soap solution against a mixture of calcium -and magnesium salts, the relative proportions of which approximate those -found in the water. - -The strength of the soap solution should be determined from time to -time, to make sure that it has not materially changed. Record all -results in parts per million of calcium carbonate. - -One English degree of hardness, Clark’s scale, is equivalent to 1 grain -per Imperial gallon of calcium carbonate. One French degree of hardness -is equivalent to 1 part per 100,000 of calcium carbonate. One German -degree of hardness is equivalent to 1 part per 100,000 of calcium oxide, -and multiplied by 17.9 gives parts per million of calcium carbonate. The -relations of these various scales are indicated in Table 7. - - Table 7.—CONVERSION TABLE FOR HARDNESS. - - ───────────────────────────┬─────────────────────────────────────────── - Unit. │ Equivalent. - ───────────────────────────┼──────────┬──────────┬──────────┬────────── - │Parts per │ Clark │ French │ German - │ million. │ degrees. │ degrees. │ degrees. - ───────────────────────────┼──────────┼──────────┼──────────┼────────── - One part per million │ 1.00│ 0.07│ 0.10│ 0.056 - One Clark degree │ 14.3│ 1.00│ 1.43│ .80 - One French degree │ 10.0│ .70│ 1.00│ .56 - One German degree │ 17.9│ 1.24│ 1.78│ 1.00 - ───────────────────────────┴──────────┴──────────┴──────────┴────────── - - - TOTAL HARDNESS BY SODA REAGENT METHOD.[47][74][81][94d] - -Add standard sulfuric acid to 200 cc. of the sample until the alkalinity -is neutralized. (See Procedure with methyl orange, p. 37.) Then apply -the non-carbonate hardness method (pp. 34–35). This method gives fairly -satisfactory estimates of total hardness of hard waters. - - - TEMPORARY HARDNESS BY TITRATION WITH ACID. - -Determine the alkalinity in presence of methyl orange (see p. 37) in the -original sample and also in the sample after boiling, cooling, restoring -to the original volume with boiled distilled water, and filtering. The -difference between the two, if any, is the temporary hardness. This is -the most accurate method of determining the temporary hardness of -ordinary waters. Iron bicarbonate is included as a part of the temporary -hardness. - - - NON-CARBONATE HARDNESS BY SODA REAGENT METHOD.[47][74][81][94d] - -The use of soda reagent does not avoid entirely the error due to -solubility of the salts of calcium and magnesium; consequently, if much -depends on the results, as in water softening, gravimetric -determinations of the calcium and magnesium that remain in solution -should be made and a correction should be applied for those amounts. - -_Reagent._—Prepare soda reagent from equal parts of sodium hydroxide and -sodium carbonate. It should be approximately tenth normal. - -_Procedure._—Measure 200 cc. of the sample and 200 cc. of distilled -water into 500 cc. Jena or similar glass Erlenmeyer flasks. Treat the -contents of each flask in the following manner. Boil 15 minutes to expel -free carbon dioxide. Add 25 cc. of soda reagent. Boil 10 minutes, cool, -rinse into 200 cc. graduated flasks, and dilute to 200 cc. with boiled -distilled water. Filter, rejecting the first 50 cc., and titrate 50 cc. -of each filtrate with N/50 sulfuric acid in the presence of methyl -orange or erythrosine indicator. The non-carbonate hardness in parts per -million of calcium carbonate is equal to 20 times the difference between -the number of cubic centimeters of sulfuric acid required for the soda -reagent in distilled water and the number of cubic centimeters of N/50 -sulfuric acid required for the soda reagent in the sample. - -Water naturally containing bicarbonate and carbonate in excess of -calcium and magnesium requires a larger amount of acid to neutralize the -sample after it has been treated than is required to neutralize the -volume of soda reagent originally added. (See p. 39.) - - - NON-CARBONATE HARDNESS BY SOAP METHOD. - -Non-carbonate hardness may be calculated for waters which are soft or -moderately hard in a fairly satisfactory manner by deducting the total -alkalinity from the total hardness by the soap method (pp. 31–34). For -waters that are very hard, and particularly those that contain much -magnesium, this method is not advised. - - - ALKALINITY.[11][18][47][97] - -The alkalinity of a natural water represents its content of carbonate, -bicarbonate, borate, silicate, phosphate, and hydroxide. Alkalinity is -determined by neutralization with standard sulfuric acid or potassium -bisulfate in the presence of phenolphthalein and either methyl orange, -erythrosine, or lacmoid as indicators. Methyl orange may be used except -in waters containing aluminium sulfate or iron sulfate. The relations -between estimates in presence of these indicators and the carbonate, -bicarbonate, and hydroxide radicles are indicated in Table 8. The -alkalinity of carbonates in the presence of phenolphthalein is different -from that in the presence of methyl orange, partly because of loss of -carbon dioxide and partly because of defects in phenolphthalein as an -indicator in such conditions. - - Table 8.—RELATIONS BETWEEN ALKALINITY TO PHENOLPHTHALEIN AND THAT TO - METHYL ORANGE, ERYTHROSINE, OR LACMOID, IN PRESENCE OF BICARBONATE, - CARBONATE, AND HYDROXIDE. - - ─────────────────┬───────────────────────────────────────────────────── - Result of │ Value of radicle expressed in terms of calcium - titration.[C] │ carbonate. - ─────────────────┼─────────────────┬─────────────────┬───────────────── - │ Bicarbonate. │ Carbonate. │ Hydroxide. - ─────────────────┼─────────────────┼─────────────────┼───────────────── - P = 0 │ T │ 0 │ 0 - P < 1/2T │ T − 2P │ 2P │ 0 - P = 1/2T │ 0 │ 2P │ 0 - P > 1/2T │ 0 │ 2(T − P) │ 2P − T - P = T │ 0 │ 0 │ T - ─────────────────┴─────────────────┴─────────────────┴───────────────── - -Footnote C: - - T = Total alkalinity in presence of methyl orange, erythrosine, or - lacmoid. P = Alkalinity in presence of phenolphthalein. - -_Reagents._—1. Sulfuric acid or potassium bisulfate. A N/50 solution. - -2. Phenolphthalein indicator. Dissolve 5 grams of a good quality of -phenolphthalein in 1 liter of 50 per cent alcohol. Neutralize with N/10 -potassium hydroxide. The alcohol should be diluted with boiled distilled -water. - -3. Methyl orange indicator. Dissolve 0.5 gram of a good grade of methyl -orange in 1 liter of distilled water. Keep the solution in the dark. - -4. Lacmoid indicator. Dissolve 2.0 grams of lacmoid in 1 liter of 50 per -cent alcohol. Dilute the alcohol with freshly boiled distilled water. - -5. Erythrosine indicator. Dissolve 0.5 gram of erythrosine (the sodium -salt) in 1 liter of freshly boiled distilled water. - - - PROCEDURE WITH PHENOLPHTHALEIN. - -Add 4 drops of phenolphthalein indicator to 50 or 100 cc. of the sample -in a white porcelain casserole or an Erlenmeyer flask over a white -surface. If the solution becomes colored, hydroxide or normal carbonate -is present. Add N/50 sulfuric acid from a burette until the coloration -disappears. - -The phenolphthalein alkalinity in parts per million of calcium carbonate -is equal to the number of cubic centimeters of N/50 sulfuric acid used -multiplied by 20 if 50 cc. of the sample was used, or by 10 if 100 cc. -was used. - - - PROCEDURE WITH METHYL ORANGE. - -Add 2 drops of methyl orange indicator to 50 or 100 cc. of the sample, -or to the solution to which phenolphthalein has been added, in a white -porcelain casserole or an Erlenmeyer flask over a white surface. If the -solution becomes yellow, hydroxide, normal carbonate, or bicarbonate is -present. Add N/50 sulfuric acid from a burette until the faintest pink -coloration appears. The methyl orange alkalinity in parts per million of -calcium carbonate is equal to the total number of cubic centimeters of -N/50 sulfuric acid used multiplied by 20 if 50 cc. of the sample was -used, or by 10 if 100 cc. was used. - - - PROCEDURE WITH LACMOID. - -Add 4 drops of lacmoid indicator to 50 or 100 cc. of the sample in a -porcelain casserole or an Erlenmeyer flask. Add N/50 sulfuric acid from -a burette until within 1 or 2 cc. of the amount necessary for -neutralization has been added. Heat the solution until bubbles of steam -begin to break at the surface. Remove the dish from the source of heat -and continue the titration until a drop of the acid striking the surface -of the liquid and sinking to the bottom of the vessel produces no change -in the uniform reddish or purple color of the solution. The calculation -is the same as for phenolphthalein alkalinity. - - - PROCEDURE WITH ERYTHROSINE. - -Add 5 cc. of neutral chloroform and 1 cc. of erythrosine indicator to 50 -or 100 cc. of the sample in a 250 cc. clear glass-stoppered bottle. If -the chloroform becomes rose colored on shaking, hydroxide, bicarbonate, -or normal carbonate is present. Add N/50 sulfuric acid from a burette -until the chloroform becomes colorless. A white surface behind the -bottle facilitates detection of a trace of color as the end-point is -approached. The calculation is the same as with phenolphthalein -alkalinity. - - - BICARBONATE. - -Bicarbonate is present if the alkalinity to phenolphthalein is less than -one-half the alkalinity to methyl orange, erythrosine, or lacmoid. The -alkalinity to methyl orange, erythrosine, or lacmoid is due entirely to -bicarbonate if there is no phenolphthalein alkalinity. If there is -phenolphthalein alkalinity the bicarbonate, in terms of calcium -carbonate, is equal to the methyl orange, erythrosine, or lacmoid -alkalinity minus twice the phenolphthalein alkalinity. Bicarbonate, -carbon dioxide as bicarbonate, and half-bound carbon dioxide can be -calculated as follows: - -Bicarbonate (HCO_{3}) = 1.22 times the bicarbonate expressed in terms of -calcium carbonate. - -Carbon dioxide (CO_{2}) as bicarbonate = 0.88 times the bicarbonate -expressed in terms of calcium carbonate. - -Half-bound carbon dioxide (CO_{2}) = 0.44 times the bicarbonate -expressed in terms of calcium carbonate. - - - NORMAL CARBONATE.[20][94] - -Normal carbonate is present if the alkalinity to phenolphthalein is -greater than zero but less than the alkalinity to methyl orange, -erythrosine, or lacmoid. If the phenolphthalein alkalinity is exactly -equal to one-half the methyl orange, erythrosine, or lacmoid alkalinity -the alkalinity is due entirely to normal carbonate. If the -phenolphthalein alkalinity is less than one-half the methyl orange, -erythrosine, or lacmoid alkalinity normal carbonate expressed in terms -of calcium carbonate is equal to twice the phenolphthalein alkalinity. -If the phenolphthalein alkalinity is greater than one-half the methyl -orange, erythrosine, or lacmoid alkalinity the normal carbonate is equal -to twice the difference between the methyl orange, erythrosine, or -lacmoid alkalinity and the phenolphthalein alkalinity. The carbonate, -carbon dioxide as carbonate, and bound carbon dioxide can be calculated -as follows: - -Carbonate (CO_{3}) = 0.6 times the normal carbonate expressed in terms -of calcium carbonate. - -Carbon dioxide as carbonate (CO_{2}) = 0.44 times the normal carbonate -expressed in terms of calcium carbonate. - -Bound carbon dioxide (CO_{2}) is the sum of the carbon dioxide as -carbonate and one-half that as bicarbonate. - - - HYDROXIDE.[20][94] - -If hydroxide, or caustic alkalinity, is present the alkalinity to -phenolphthalein is greater than one-half the alkalinity to methyl -orange, erythrosine, or lacmoid; the alkalinity is due entirely to -hydroxide if the phenolphthalein alkalinity is equal to the methyl -orange, erythrosine, or lacmoid alkalinity. If the phenolphthalein -alkalinity is more than half and less than all the methyl orange, -erythrosine, or lacmoid alkalinity, hydroxide, expressed in terms of -calcium carbonate, is equal to twice the phenolphthalein alkalinity -minus the methyl orange, erythrosine, or lacmoid alkalinity. - - - ALKALI CARBONATES. - -Waters which contain sodium or potassium carbonates or bicarbonates -contain all of their calcium and magnesium as carbonates or -bicarbonates. That is, they possess no non-carbonate hardness (sulfates, -nitrates or chlorides of calcium and magnesium). - -The most accurate method is to determine the total alkalinity by -titration with N/50 sulfuric acid, using methyl orange, erythrosine, or -lacmoid as an indicator; then determine the calcium and magnesium -content; and subtract from the total alkalinity the computed alkalinity -due to the calcium and magnesium expressed in terms of calcium -carbonate. The remainder is the alkalinity due to carbonates and -bicarbonates of sodium and potassium. - -This determination may also be made by applying the method, for -non-carbonate hardness with soda reagent (see p. 35), and by noting the -excess of acid required to neutralize the alkaline carbonates originally -present. - -With present information as to solubilities of the normal carbonates of -calcium and magnesium, it is difficult in their presence to measure -slight quantities of carbonates of sodium or potassium. - - - ACIDITY.[24d][37] - -Waters may have an acid reaction because of the presence of free carbon -dioxide, mineral acids, or some of their salts, especially those of iron -and aluminium. - -_Reagents._—1. N/50 sodium carbonate. Dissolve 1.06 grams of anhydrous -sodium carbonate in 1 liter of boiled distilled water that has been -cooled in an atmosphere free from carbon dioxide. Preserve this solution -in bottles of resistant glass protected from the air by tubes filled -with soda-lime. One cc. is equivalent to 1 mg. of CaCO_{3}. - -2. N/22 sodium carbonate. Dissolve 2.41 grams of anhydrous sodium -carbonate in 1 liter of boiled distilled water that has been cooled in -an atmosphere free from carbon dioxide. Preserve this solution in -bottles of resistant glass protected from the air by tubes filled with -soda-lime. One cc. is equivalent to 1 mg. of CO_{2}. - -3. Phenolphthalein indicator (see p. 36). - -4. Methyl orange indicator (see p. 36). - - - TOTAL ACIDITY. - -_Procedure._—Add 4 drops of phenolphthalein indicator to 50 or 100 cc. -of the sample in a white porcelain casserole or an Erlenmeyer flask over -a white surface. Add N/50 sodium carbonate until the solution turns -pink. The total acidity in parts per million of calcium carbonate is -equal to the number of cubic centimeters of N/50 sodium carbonate used -multiplied by 20 if 50 cc. of the sample was used, or by 10 if 100 cc. -was used. - - - FREE CARBON DIOXIDE.[20][23][61][87][88][94a][118] - -Carbon dioxide may exist in water in three forms—free carbon dioxide, -bicarbonate (pp. 37–38), and carbonate (p. 38). One-half the carbon -dioxide as bicarbonate is known as the half-bound carbon dioxide. The -carbon dioxide as carbonate plus one-half that as bicarbonate is known -as the bound carbon dioxide. - -_Procedure._—Pour 100 cc. of the sample into a tall narrow vessel, -preferably a 100 cc. Nessler tube. Add 10 drops of phenolphthalein -indicator, and titrate rapidly with N/22 sodium carbonate, stirring -gently, until a faint but permanent pink color is produced. The free -carbon dioxide (CO_{2}) in parts per million is equal to 10 times the -number of cubic centimeters of N/22 sodium carbonate used. - -Because of the ease with which free carbon dioxide escapes from water, -particularly when the gas is present in large amount, a special sample -should be collected for this determination, which should preferably be -made at the time of collection. If the analysis cannot be made at the -time of collection approximate results with water not too high in free -carbon dioxide may be obtained on samples collected in bottles -completely filled so as to leave no air space under the stopper. Bottled -samples should be kept, until tested, at a temperature lower than that -of the water when collected. If mineral acids or certain salts are -present correction must be made. At best, the results of the titration -are uncertain because the proper end-point for correct results differs -in color with different types of water. - - - FREE MINERAL ACIDS. - -_Procedure._—Add 2 drops of methyl orange indicator to 50 or 100 cc. of -the sample in a white porcelain casserole or an Erlenmeyer flask over a -white surface. Add N/50 sodium carbonate from a burette until the pink -coloration of the solution disappears. The acidity due to free mineral -acids, expressed in terms of calcium carbonate, is equal to the number -of cubic centimeters of N/50 sodium carbonate used multiplied by 20 if -50 cc. of the sample was used, or by 10 if 100 cc. was used. - - - MINERAL ACIDS AND SULFATES OF IRON AND ALUMINIUM.[24d][37] - -_Procedure._—Modify the method for free mineral acids by titrating the -water at boiling temperature in the presence of phenolphthalein -indicator. The acidity due to free mineral acids and sulfates of iron -and aluminium, expressed in terms of calcium carbonate, is equal to the -number of cubic centimeters of N/50 sodium carbonate used multiplied by -20 if 50 cc. of the sample was used, or by 10 if 100 cc. was used. - -The acidity due to sulfates of iron and aluminium is equal to the -acidity due to mineral acids and sulfates minus the acidity due to -mineral acids. The acidity due to ferrous and ferric sulfate can be -calculated from the determined amount of these salts (pp. 43–48). The -acidity due to aluminium sulfate is equal to the acidity due to total -acid sulfates minus that due to iron sulfates. - -Acidity shall be reported in parts per million of calcium carbonate -(CaCO_{3}). Sulfate (SO_{4}) equals parts per million of calcium -carbonate multiplied by 0.96. - -Carbon dioxide (CO_{2}) equals parts per million of calcium carbonate -multiplied by 0.44. - - - CHLORIDE.[16] - -Chloride in water and sewage has its origin in common salt, from mineral -deposits in the earth, from ocean vapors carried inland by the wind, or -from polluting materials like sewage and trade wastes, which contain the -salt used in the household and in manufacturing. Comparison of the -chloride content of a water with that of other waters in the vicinity -known to be unpolluted frequently affords useful information as to its -sanitary quality. If, however, the chloride normally exceeds 20 parts -per million because of chloride-bearing mineral deposits the chloride -content of a water has little sanitary significance. - -_Reagents._—1. Standard sodium chloride solution. Dissolve 16.48 grams -of pure fused sodium chloride in 1 liter of distilled water. Dilute 100 -cc. of this stock solution to 1 liter in order to obtain a standard -solution each cubic centimeter of which contains 0.001 gram of chloride. - -2. Standard silver nitrate solution. Dissolve about 2.40 grams of silver -nitrate crystals in 1 liter of distilled water. Standardize this with -the standard salt solution, and adjust, correcting for volume (see p. -43), so that 1 cc. will be exactly equivalent to 0.0005 gram of -chloride. - -3. Potassium chromate indicator. Dissolve 50 grams of neutral potassium -chromate in a little distilled water. Add enough silver nitrate to -produce a slight red precipitate. Filter and dilute the filtrate to 1 -liter with distilled water. - -4. Aluminium hydroxide. Electrolyze ammonia-free water, using aluminium -electrodes. Wash the precipitate until it is free from chloride, -ammonia, and nitrite. Or dissolve 125 grams of potassium or ammonium -alum in 1 liter of distilled water. Precipitate the aluminium by adding -cautiously ammonium hydroxide. Wash the precipitate in a large jar by -successive additions and decantations of distilled water until free from -chloride, nitrite, and ammonia. - -_Procedure._—Add 1 cc. of potassium chromate indicator to 50 cc. of the -sample in a 6–inch white porcelain evaporating dish or a 150 cc. -Erlenmeyer flask over a white surface. Titrate with the silver nitrate -solution under similar conditions of volume, light, and temperature as -were used in standardizing the silver nitrate until a faint reddish -coloration is perceptible. The detection of the end-point is facilitated -by comparison of the contents of the porcelain dish with those of -another dish containing the same quantity of potassium chromate -indicator in 50 cc. of distilled water. Some analysts prefer to make the -titration in a dark-room provided with a yellow light. The end-point is -very sharp by electric light and also by daylight with photographic -yellow glass. The titration may be made in Nessler tubes[68a] if the -solutions are standardized under similar conditions. - -If the amount of chloride is very high use 25 cc., or even a smaller -quantity, dilute the volume taken to 50 cc. with distilled water. If the -amount of chloride is very low concentrate 250 cc. of the sample to 50 -cc. by evaporation. Rotate the liquid to make sure that no residue -remains undissolved on the walls of the dish, and, if necessary, use a -rubber-tipped glass rod to assist in this operation. - -Chloride is determined by some observers by extracting with hot -distilled water the residue in the platinum dish in the determination of -the residue on evaporation and proceeding as just described. This is -permissible if a little sodium carbonate is added before evaporation to -prevent loss of chloride through decomposition of magnesium chloride in -the residue. - -If the sample has a color greater than 30 it should be decolorized by -shaking it thoroughly with washed aluminium hydroxide (3 cc. to 500 cc. -of the sample) and allowing the precipitate to settle. Make the -determination on a portion of the clarified sample, filtered if -necessary. If the sample is acid, neutralize it with sodium carbonate; -if hydroxide is present, add dilute sulfuric acid until the cold liquid -will just discharge the color of phenolphthalein. If the presence of -sulfide and sulfocyanate renders it necessary, make proper -corrections[24c][100b] or modifications in treatment. - -Make correction for the error due to variations in the volume of the -liquid and precipitate by means of the formula[39] X = 0.003V + 0.02, in -which X = the correction in cubic centimeters of silver nitrate solution -and V = cubic centimeters of liquid at the end of the titration. If 50 -cc. of the sample is titrated chloride (Cl) in parts per million is -equal to the number of cubic centimeters of silver nitrate solution -multiplied by 10. The correction to be applied is 0.2 cc. unless unusual -accuracy is required. - - - IRON.[94b][98] - -Iron occurs in natural waters in both ferrous and ferric condition, -depending on the source of the sample. In ground waters the iron is -usually in an unoxidized and soluble condition, sometimes combined with -carbonic or sulfuric acid, and also in combination with organic matter. -Many waters, especially those that have been exposed to the air, contain -the iron in the form of a colloidal hydroxide. Silt-bearing waters often -contain much iron in suspension, usually in an oxidized form. Sewages -and sewage effluents, particularly those receiving manufacturing wastes, -contain various forms of iron of different degrees of solubility, -oxidation, and coagulation. - - - TOTAL IRON.[59][63b] - - - COLORIMETRIC METHOD. - -_Reagents._—1. Standard iron solution. Dissolve 0.7 gram of crystallized -ferrous ammonium sulfate in 50 cc. of distilled water to which 20 cc. of -dilute sulfuric acid has been added. Warm the solution slightly and add -potassium permanganate until the iron is completely oxidized. Dilute the -solution to 1 liter. One cc. of the standard solution equals 0.1 mg. Fe. - -2. Potassium sulfocyanide solution. Dissolve 20 grams of the salt in 1 -liter of distilled water. - -3. Dilute hydrochloric acid. One volume of acid (Sp. gr. 1.2) and one -volume of distilled water. This shall be free from nitric acid. - -4. N/5 potassium permanganate. Dissolve 6.30 grams of the salt in -distilled water and dilute to 1 liter. - -5. Hydrochloric acid. Concentrated, free from iron. - -6. Nitric acid. Concentrated, free from iron. - -7. Nitric acid. 5N, free from iron. - -_First procedure._—Evaporate 100 cc. of the water to dryness, or use the -residue left after the determination of residue on evaporation (p. 29). -Ignite the residue at a low red heat taking care not to heat it hot -enough to make the iron difficultly soluble. Cool the dish and add 5 cc. -of concentrated hydrochloric acid. Moisten the inner surface of the -dish. Warm the solution for two or three minutes, and again moisten the -inner surface of the dish by permitting the hot acid to flow over it. -Wash the hot solution from the dish into a 50 cc. Nessler tube, -filtering if necessary through paper that has been washed with hot -water. Dilute to 50 cc., and add 3 drops of potassium permanganate -solution. Add 5 cc. of potassium sulfocyanide solution, mix, and compare -with standards. - -If it is not convenient to use the residue on evaporation and if the -sample is relatively free from organic matter, boil 50 cc. of the sample -with 5 cc. of 5N nitric acid for five minutes. Add a few drops of -permanganate and 5 cc. of potassium sulfocyanide and compare with -standards, using nitric acid in place of hydrochloric acid in the -standards. This method is excellent for ground waters. The permanganate -and acid liberate chlorine in water high in chloride, and produce a -permanent yellow color which interferes with the determination, unless -the sample is first diluted to 50 cc. An excess of permanganate, -reacting with hydrochloric acid, causes similar trouble. The amounts of -hydrochloric acid, 5 cc., and of sulfocyanide, 5 cc., should be -approximately measured because more acid lightens the color whereas more -sulfocyanide deepens it. This is especially important if permanent -standards are used. - -_Second procedure._—For surface waters containing small amounts of -organic matter, the method of Klut[59] is recommended. Samples -containing small amounts of iron should be concentrated, if possible, -until at least 0.5 mg. of iron is present in the volume tested. Boil the -sample in a beaker with 2 to 3 cc. of concentrated nitric acid free from -iron, adding permanganate if necessary to destroy the organic matter. To -the hot liquid add ammonia in slight excess and warm until the smell of -ammonia is hardly discernible. Filter and wash with water at 70° to 80° -C. containing a little ammonia. Dissolve the iron in the beaker and on -the filter paper in 5 cc. of concentrated hydrochloric acid, and wash -with hot water until the iron is all dissolved, collecting the filtrate -in a 50 cc. Nessler tube. Dilute to 50 cc. Add potassium sulfocyanide -and determine the iron by comparison with standards. - - - COMPARISON WITH IRON STANDARDS. - -_First procedure._—Prepare standards containing amounts of standard iron -solution ranging from 0.05 to 4 cc. according to the quantity of iron in -the sample. Dilute these amounts with water to about 40 cc. Add 5 cc. of -dilute hydrochloric acid and 3 drops of potassium permanganate to each -tube and dilute to 50 cc. Add 5 cc. of the potassium sulfocyanide to -each of the standard solutions at the same time that it is added to the -samples of water under examination, and compare immediately after -mixing. If 100 cc. of the sample is used the iron in parts per million -is equal to the number of cubic centimeters of the standard iron -solution in the standard that the sample matches. - -_Second procedure._—For a small number of determinations it is more -convenient to run the standard iron solution into a Nessler tube -containing the acid, distilled water, and potassium sulfocyanide until -the color matches that of the sample tested. When determining iron in -three or four samples the colors may be matched in the order of their -intensity and the volumes of standard iron solution required for each -tube may be read from the burette. - - - COMPARISON WITH PERMANENT STANDARDS. - -_Reagents._—1. Platinum solution. Dissolve 2 grams of potassium platinic -chloride (PtCl_{4}.2KCl) in distilled water, add 100 cc. of concentrated -hydrochloric acid, and dilute to 1 liter with distilled water. - -2. Cobalt solution. Dissolve 24 grams of dry cobaltous chloride crystals -(CoCl_{2}.6H_{2}O) in a small amount of distilled water, add 100 cc. of -strong hydrochloric acid, and dilute to 1 liter with distilled water. - -_Procedure._—Prepare a series of permanent standards by diluting to 50 -cc. with distilled water the amounts of platinum and cobalt solutions, -in 50 cc. Nessler tubes, indicated in Table 9. Compare the sample with -these standards, and calculate the parts per million of iron. - - Table 9.—PREPARATION OF PERMANENT STANDARDS FOR THE DETERMINATION OF - IRON. - - ───────────────────────┬───────────────────────┬─────────────────────── - Value in standard iron │ Platinum solution. │ Cobalt solution. - solution. │ │ - ───────────────────────┼───────────────────────┼─────────────────────── - _cc._ │ _cc._ │ _cc._ - 0.0│ 0│ 0.0 - .1│ 2│ 1.0 - .3│ 6│ 3.0 - .5│ 10│ 5.0 - .7│ 14│ 7.5 - 1.0│ 20│ 11.0 - 1.5│ 28│ 17.0 - 2.0│ 35│ 24.0 - 2.5│ 39│ 32.0 - 3.0│ 39│ 43.0 - 3.5│ 40│ 55.0 - ───────────────────────┴───────────────────────┴─────────────────────── - - - VOLUMETRIC METHOD.[24f] - -Some samples of sewage and water mixed with trade wastes and mine -drainage contain so much iron that it is preferable to use the -volumetric method described on page 57 for the determination of both -total and dissolved iron, rather than to work with quantities small -enough to permit application of the colorimetric methods just described. -If iron is present in large quantities in suspension, as in some sewages -and septic tank effluents, it may be filtered off and the residue -washed, ignited, and fused with potassium and sodium carbonate. The -fusion is then extracted with hydrochloric acid and the iron determined -as on page 57. - -Samples containing much organic matter should be evaporated to dryness -with 0.5 cc. of concentrated sulfuric acid and the residue then ignited -before estimation of iron. - - - DISSOLVED IRON. - -Determine, by the method described for total iron, the iron in the -sample after filtration. Iron may precipitate from some samples during -filtration. - - - SUSPENDED IRON. - -The suspended iron is the difference between total iron in the -unfiltered sample and dissolved iron in the filtered sample. - - - FERROUS IRON.[24e] - -Determine the total ferrous iron in an unfiltered sample and the -dissolved ferrous iron in a filtered sample. - -_Reagents._—1. Standard iron solution. Dissolve 0.7 gram of crystallized -ferrous ammonium sulfate in a large volume of freshly boiled distilled -water to which 10 cc. of dilute sulfuric acid has been added and dilute -to 1 liter. This solution should be freshly prepared when needed. One -cc. of this standard solution contains 0.1 mg. of Fe. - -2. Potassium ferricyanide solution. Dissolve 5 grams of the salt in 1 -liter of distilled water. Use a freshly prepared solution. - -3. Dilute sulfuric acid. Dilute 1 part of sulfuric acid, specific -gravity 1.84, with 5 parts of distilled water. - -_Procedure._—Add 10 cc. of dilute sulfuric acid to 50 cc. of the sample, -remove the suspended matter by filtration if necessary, and add 15 cc. -of potassium ferricyanide solution. Dilute the solution to 100 cc. with -distilled water. Compare the color developed in the sample with that in -standards made at the same time from the ferrous iron solution. Place in -100 cc. Nessler tubes, in the following order, 75 cc. of distilled -water, 10 cc. of dilute sulfuric acid, and 15 cc. of potassium -ferricyanide solution, and mix well the contents of each tube. Prepare -as many tubes in this way as are needed. Add various quantities of -standard ferrous iron solution to several tubes, mix well, and compare -the resulting colors with the samples _immediately_. - - - FERRIC IRON. - -The amount of ferric iron in solution and suspension is equal to the -difference between the total iron and the ferrous iron obtained by the -methods described. - - - MANGANESE. - -If the sample contains less than 10 parts per million of manganese, use -a colorimetric method in which the manganous salt is oxidized to -permanganate and the color produced thereby is compared with that of a -standard solution similarly treated. The persulfate method and the -bismuthate method are suitable. If the sample contains more than 10 -parts per million of manganese it is sometimes preferable to use a -volumetric or gravimetric method. - - - PERSULFATE METHOD. - -_Reagents._—1. Nitric acid. Dilute concentrated nitric acid with an -equal volume of distilled water. Free the diluted acid from brown oxides -of nitrogen by aeration. - -2. Silver nitrate. Dissolve 20 grams of silver nitrate in 1 liter of -distilled water. - -3. Standard manganous sulfate. Dissolve 0.288 gram of purest potassium -permanganate in about 100 cc. of distilled water. Acidify the solution -with sulfuric acid and heat to boiling. Add slowly a sufficient quantity -of dilute solution of oxalic acid to discharge the color. Cool and -dilute to 1 liter. One cc. of this solution contains 0.1 mg. of -manganese. - -4. Ammonium persulfate. Crystals, free from chloride. - -_Procedure._—Use an amount of the sample that contains not more than 0.2 -mg. of manganese. Add 2 cc. of nitric acid and boil down to about 50 cc. -Precipitate the chloride with silver nitrate solution, adding at least 1 -cc. in excess. Shake and heat to coagulate the precipitate, and filter. -A sample that contains much chloride should be evaporated with a few -drops of sulfuric acid until white fumes appear and then diluted before -the nitric acid and silver nitrate are added as directed above. If the -sample is highly colored by organic matter it should be evaporated with -sulfuric acid, and the residue ignited and dissolved in dilute nitric -acid. Add about 0.5 gram of ammonium persulfate crystals and warm the -solution until the maximum permanganate color is developed. This usually -takes about ten minutes. At the same time prepare standards by diluting -portions of 0.2, 0.4, 0.6 cc., etc. of the standard manganous sulfate -solution to about 50 cc. and treating them exactly as the sample was -treated. Transfer the sample and the standards to 50 cc. Nessler tubes, -and compare the colors immediately. Manganese in parts per million is -equal to the number of cubic centimeters of standard manganous sulfate -solution in the tube that the sample matches multiplied by 100, divided -by the number of cubic centimeters of the sample used. - - - BISMUTHATE METHOD.[2a][113] - -_Reagents._—1. Nitric acid. Dilute 1 part of concentrated nitric acid -with 4 parts of distilled water. Free the dilute acid from brown oxides -of nitrogen by aeration. - -2. Sulfuric acid. Dilute 1 part of concentrated sulfuric acid with 3 -parts of distilled water. - -3. Dilute sulfuric acid. Dilute 25 cc. of concentrated acid to 1 liter -with distilled water. Add enough permanganate solution to color faintly -the dilute acid. - -4. Standard manganous sulfate. The standard solution of manganous -sulfate prepared as described under persulfate method (p. 48) should be -used and the standards should be prepared by following the same -procedure as is used for the sample. This solution is more permanent -than a solution of potassium permanganate, which may, however, be used. -To prepare it dissolve 0.288 gram of potassium permanganate in distilled -water and dilute the solution to 1 liter. - -5. Sodium bismuthate. Purest dry salt. - -_Procedure._—Use an amount of the sample that contains not more than 0.2 -mg. of manganese. Add 0.5 cc. of sulfuric acid and evaporate to dryness. -Heat until the sulfuric acid is volatilized and ignite the residue. -Dissolve in 40 cc. of nitric acid, add about 0.5 gram of sodium -bismuthate, and heat until the permanganate color disappears. Add a few -drops of a solution of ammonium or sodium bisulfate to clear the -solution and again boil to expel oxides of nitrogen. Remove from the -source of heat, cool to 20° C., again add 0.5 gram of sodium bismuthate, -and stir. When the maximum permanganate color has developed, filter -through an alundum or Gooch crucible containing an asbestos mat ignited -and washed with potassium permanganate. Wash the precipitate with dilute -sulfuric acid until the washings are colorless. Transfer the filtrate to -a 50 cc. Nessler tube and compare the color of it with that of standards -prepared from the potassium permanganate solution. To prepare the -standards, dilute portions of 0.2, 0.4, 0.6 cc., etc. of the -permanganate solution to 50 cc. with dilute sulfuric acid. The content -of manganese is calculated as described under persulfate method (p. 49). - - - LEAD, ZINC, COPPER, AND TIN.[7][60] - -Determinations of lead, zinc, copper, and tin are important in certain -mining regions and in places where the water has a solvent action on -pipes and other containers. The use of certain “germicides” also makes -it necessary to test for some of these metals. - -Lead, zinc, and copper may be determined colorimetrically or -electrolytically. The colorimetric methods are not so accurate as a -combination of both, and are chiefly of value as qualitative tests. - -It is possible to make a rough estimation of the amount of lead in clear -waters by acidifying with acetic acid, saturating with hydrogen sulfide, -and comparing the color produced with that produced by standard lead -solutions in Nessler tubes, treated in similar manner. This method, -however, is not applicable if the water is colored or contains iron. - -_Reagents._—1. Standard lead solution. Dissolve 1.60 grams of lead -nitrate (Pb(NO_{3})_{2}) in 1 liter of distilled water. One cc. of this -solution contains 1 mg. of lead (Pb). As a check it is desirable to -determine lead as sulfate in a measured portion of this solution. - -2. Standard copper solution. Dissolve about 0.8 gram of copper sulfate -crystals (CuSO_{4}.5H_{2}O) in water and, after the addition of 1 cc. of -concentrated sulfuric acid, dilute the solution to 1 liter. Determine -the copper in 100 cc. of this solution in the usual way by electrolytic -deposition. Dilute the solution so that 1 cc. contains 0.2 milligram -copper (Cu). This solution is permanent. - -3. Ammonium chloride. Twenty-five per cent solution. - -4. Ammonium acetate. Fifty per cent solution. - -5. Ammonium hydroxide. (Sp. gr. 0.96.) - -6. Hydrogen sulfide. Saturated solution. - -7. Potassium sulfide. An alkaline solution of potassium sulfide made by -mixing equal volumes of 10 per cent potassium hydroxide and a saturated -aqueous solution of hydrogen sulfide. - -8. Potassium oxalate. Crystals. - -9. Potassium sulfate. Crystals. - -10. Alcohol. Ninety-five per cent. - -11. Alcohol. Fifty per cent. - -12. Acetic acid. Fifty per cent. - -13. Nitric acid. Concentrated acid (Sp. gr. 1.42). - -14. Nitric acid. Dilute 1 part of the concentrated acid to 10 parts with -distilled water. - -15. Hydrochloric acid. (Sp. gr. 1.20.) - -16. Sulfuric acid. Concentrated acid (Sp. gr. 1.84). - -17. Sulfuric acid. Dilute the concentrated acid with an equal volume of -distilled water. - -18. Urea. Crystals. - - - LEAD. - -Concentrate (1)[D] rapidly by boiling in a 7–inch porcelain dish over a -free flame 3 or 4 liters of the sample to be tested, or more if very -small amounts of the metals are present, to a volume of about 30 cc. Add -10 or 15 cc. of ammonium chloride solution to assist in the separation -of the sulfides, then add a few drops of concentrated ammonium -hydroxide, and saturate with hydrogen sulfide. Allow to stand some time, -preferably over night, add a little more ammonium hydroxide and hydrogen -sulfide, boil the contents of the dish a few minutes, and filter. The -precipitate (2) may consist of lead, zinc, copper, and iron sulfides and -the suspended organic matter. The soluble coloring matter is in the -filtrate (3). Wash the precipitate a few times with hot water, place the -precipitate and the filter paper in the original dish and boil with -dilute nitric acid, rubbing down the sides of the dish, if necessary, to -detach any adhering sulfide precipitate. After again filtering and -washing several times with hot water, evaporate the filtrate and -washings in the original dish to a bulk of 10 to 15 cc., cool, add 5 cc. -of concentrated sulfuric acid, and heat until copious fumes of sulfuric -acid are evolved. - -Footnote D: - - The numbers in parentheses refer to tables 10–12, pages 55–56. - -If lead is present dilute the contents of the dish slightly with water, -and treat them with 150 cc. of 50 per cent alcohol, in which the lead -sulfate is insoluble. Allow to stand some time, preferably over night, -filter off the lead sulfate, and wash it with 50 per cent alcohol. Save -the filtrate for the determination of zinc. - -Dissolve the precipitate of lead sulfate by boiling the filter -containing it in ammonium acetate solution in a porcelain dish. (4). -Filter into a 50 cc. Nessler tube and wash the filter with boiling water -containing a little ammonium acetate. Divide this filtrate in halves and -treat one-half with saturated hydrogen sulfide water in order to get an -approximation of the amount of lead present. To the other half, or an -aliquot portion, if a large amount of lead is present, add a few drops -of acetic acid, then an excess of saturated hydrogen sulfide solution, -and compare the color with that of standards made by treating known -amounts of the standard lead solution with a little acetic acid, -ammonium acetate, and hydrogen sulfide. - - - ZINC. - -If zinc is present and copper is absent concentrate the filtrate from -the lead sulfate to expel the alcohol, and remove the iron by adding an -excess of ammonium hydroxide. Filter, wash, and acidify the filtrate -with sulfuric acid. Concentrate the filtrate to about 150 cc. and -transfer to a weighed platinum dish. Add 2 grams of potassium oxalate -and 1.5 grams of potassium sulfate. Deposit the zinc electrolytically by -means of a current of about 0.3 ampere for three hours. After deposition -is complete and while the current is on, siphon off the solution and at -the same time run into the dish a stream of distilled water in order to -expel the free sulfuric acid, which might dissolve some of the zinc if -the circuit were broken. After the acid has been removed break the -circuit, wash the dish with water, then with 95 per cent alcohol, dry at -70° C., cool, and weigh it. The difference between this weight (10) and -the weight of the platinum dish equals the amount of metallic zinc. Some -difficulty has been experienced in this determination in obtaining pure -reagents. It is therefore advisable to make blank determinations with -each new lot of reagents and to correct the results if necessary. - -If copper also is present (5) concentrate the filtrate from the lead -sulfate until the alcohol is expelled, and add an excess of ammonium -hydroxide. (6) Remove any iron precipitate by filtration. Neutralize the -filtrate (7) with sulfuric acid, and add 2 cc. of concentrated sulfuric -acid and 1 gram of urea. Electrolyze the solution and determine copper -colorimetrically as described in the procedure for copper (p. 54). After -the copper has been deposited add ammonium hydroxide to the solution -containing the zinc until nearly all the sulfuric acid has been -neutralized, concentrate to slightly less than the capacity of the -platinum dish, add 1.5 grams of potassium sulfate and 2 grams of -potassium oxalate, and electrolyze for zinc. As this solution is usually -saturated with ammonium salts due to neutralizing the large quantity of -sulfuric acid, it is frequently impossible to get the zinc deposited -firmly on the dish before the salts interfere by crystallization. To -avoid this difficulty, dilute half the solution and electrolyze it for -zinc; or, if the amount of zinc is very small, precipitate the zinc as -sulfide in acetic acid solution, wash, ignite to oxide, and weigh the -precipitate. This difficulty will not be encountered if copper is absent -as there will then be no excess of ammonium salts. - -If lead and copper are known to be absent and zinc alone is to be -determined (13), after treating with sulfuric acid for separation of -lead, slightly dilute the contents of the dish. Add an excess of -ammonium hydroxide to precipitate iron and filter. Make the filtrate -slightly acid with sulfuric acid, concentrate to about 150 cc., transfer -to a weighed platinum dish, add potassium oxalate and sulfate, and -electrolyze the solution as described for deposition of zinc. - - - COPPER.[77] - -Use 1 liter of a sample containing 0.1 to 1.0 part per million of -copper, and proportionate amounts for other concentrations. Evaporate to -about 75 cc., and wash into a 100 cc. platinum dish. Add 2 cc. of dilute -sulfuric acid for clear and soft waters; add more acid to very alkaline -waters to offset the alkalinity; add 5 cc. of acid to waters carrying -much organic matter or clay to insure the formation of a soluble copper -salt. Then place the dish as the anode in a direct current circuit, -suspend a spiral wire cathode in the solution so that it is parallel to -and about half an inch from the bottom of the dish, and close the -circuit. - -Electrolyze for about four hours with occasional stirring, or over -night, if convenient. The current may be supplied by two gravity cells -in series, yielding a current through the solution of about 0.02 ampere. -Lift out the cathode without previously opening the circuit, and immerse -the spiral in a small amount of dilute nitric acid previously heated to -boiling. Wash off the wire and evaporate the nitric acid solution to -dryness on the water bath. If the presence of silver is suspected add a -few drops of hydrochloric acid before evaporation. Dissolve the residue -in water and wash it into a 50 cc. Nessler tube. Dilute to 50 cc. and -add 10 cc. of the potassium sulfide solution. The color of the copper -sulfide develops at once and is fairly permanent, lasting at least -several hours. Add 10 cc. of the potassium sulfide solution to a similar -tube containing 50 cc. of distilled water, and then add to it standard -copper solution in 0.2 cc. portions until the colors of the two tubes -match. If 1 liter of the sample is used copper in parts per million is -equal to the number of cubic centimeters of standard copper solution -required to match the color of the sample multiplied by 0.2. - - - TIN. - -Small quantities of tin are occasionally found in waters that have -passed through tin or tin-lined pipes. This metal, if present, is -precipitated with the iron by ammonia in the lead, zinc, and copper -separations. In the method for copper alone, it is removed in the same -way and may be further avoided by dissolving the sulfides in -concentrated nitric acid. Any tin present will then separate as an -insoluble compound, which may be ignited and weighed as the oxide -(SnO_{2}). - -The following schematic tables illustrate the procedures given. - - Table 10.—SCHEME FOR THE SEPARATION OF LEAD, ZINC, AND COPPER. - - ─────────────────────────────────────────────────────────────────────── - 1. Concentrate sample. Add 10 cc. NH_{4}Cl, a few drops NH_{4}OH and - saturate with H_{2}S. Allow to stand, add more NH_{4}OH and H_{2}S. - Boil, filter, and wash. - ────────────────────────────────────────────────────────┬────────────── - 2. Dissolve the precipitate in dilute HNO_{3}. Filter │3. Reject the - and wash. Evaporate to 10 or 15 cc. Cool. Add 5 cc. │filtrate which - concentrated H_{2}SO_{4}, and heat until white fumes are│contains the - given off. Dilute slightly and treat with 150 cc. of 50 │coloring - per cent alcohol. Allow to stand; filter, and wash with │matter. - 50 per cent alcohol. │ - ──────────────────────────┬─────────────────────────────┤ - 4. The precipitate │5. The filtrate contains the │ - contains the Pb. Dissolve │Zn and Cu. Concentrate to │ - in NH_{4}C_{2}H_{3}O_{2} │expel alcohol. Add excess of │ - solution. Filter into a 50│NH_{4}OH, filter and wash │ - cc. Nessler tube and wash │precipitate. │ - with water containing ├──────────────┬──────────────┴────────────── - NH_{4}C_{2}H_{3}O_{2}. │6. Reject the │7. The filtrate contains the - Divide filtrate in halves.│precipitate │Zn and Cu. Neutralize with - Saturate one-half with │which contains│H_{2}SO_{4}. Add 10 cc. - H_{2}S. Determine the Pb │the Fe. │concentrated H_{2}SO_{4} and - in the other half by │ │1 g. urea. Electrolyze for - adding HC_{2}H_{3}O_{2} │ │two hours with a current of - and H_{2}S and comparing │ │0.5 ampere. Break circuit, - with standards containing │ │empty dish and wash. - known amounts of Pb. │ │ - ──────────────────────────┼──────────────┴───────────────────────────── - 8. The deposit is Cu. │9. The solution contains the Zn. Nearly - Immerse the cathode in a │neutralize with NH_{4}OH. Concentrate to - small amount of hot, │less than the capacity of the dish. Add 2 g. - dilute HNO_{3}; wash off │K_{2}C_{2}O_{4} and 1.5 g. K_{2}SO_{4}. - and evaporate to dryness. │Electrolyze for 3 hours with a current of - Take up in water and wash │0.3 ampere. Siphon off solution, break - into a Nessler tube. Make │circuit, wash with water, then alcohol, dry - up to mark, and add 10 cc.│at 70° C., cool and weigh. - of potassium sulfide ├──────────────────────────────────────────── - solution. Compare with │10. The weighed residue is metallic Zn. - standard. If large amount │ - is present, dry and weigh │ - as Cu. │ - ──────────────────────────┴──────────────────────────────────────────── - - Table 11.—SCHEME FOR DETERMINATION OF COPPER ONLY. - - ─────────────────────────────────────────────────────────────────────── - 11. Concentrate sample to 75 cc. Add 2 cc. conc. H_{2}SO_{4} for clear, - soft waters and 5 cc. for alkaline or turbid waters. Electrolyze - following procedure in 7 and 8. - ─────────────────────────────────────────────────────────────────────── - - Table 12.—SCHEME FOR DETERMINATION OF ZINC ONLY. - - ─────────────────────────────────────────────────────────────────────── - 13. Follow scheme for all three metals as given in Table 10 through - section 5. Nearly neutralize the filtrate with H_{2}SO_{4}, concentrate - to less than the capacity of the dish and electrolyze as directed in - section 9. - ─────────────────────────────────────────────────────────────────────── - - - MINERAL ANALYSIS. - - - RESIDUE ON EVAPORATION. - -See description of method (p. 29). The residue should be dried one hour -at 180° C. Turbid waters should be filtered, and the composition of the -suspended matter should be determined separately or the amount of it -reported as suspended matter. - - - ALKALINITY AND ACIDITY. - - See description of method (pp. 35–41). - - - CHLORIDE. - - See description of method (pp. 41–43). - - - NITRATE NITROGEN. - - See description of method (pp. 23–25). - - - SEPARATION OF SILICA, IRON, ALUMINIUM, CALCIUM, AND MAGNESIUM.[10][48] - - - SILICA. - -Evaporate in platinum 100 to 1,000 cc. of the sample or sufficient if -possible to form a residue weighing 0.4 to 0.6 gram, and preferably -containing 0.1 to 0.2 gram of calcium. When the residue is nearly dry -add 1 cc. of hydrochloric acid (1 to 1) and, after moistening the sides -of the dish, evaporate to dryness. Dry at 180° C. and if much organic -matter is present char it in a radiator. Moisten the residue with dilute -hydrochloric acid and expel the excess of acid by heating on the water -bath. Add a few drops of hydrochloric acid, dissolve in hot water, and -filter. Wash the residue with hot water. Evaporate the filtrate to -dryness, repeat the filtration, and combine the two residues. If great -accuracy is not required the second evaporation with hydrochloric acid -may be omitted. Ignite and weigh the insoluble residue. Add 2 drops of -concentrated sulfuric acid and a little hydrofluoric acid, volatilize -the acids, ignite, and weigh again. Report the loss in weight as silica -(SiO_{2}). A weight of non-volatile matter exceeding 0.5 mg. should be -analyzed. - - - IRON AND ALUMINIUM. - -Heat to boiling the filtrate from the insoluble residue, oxidize with -concentrated nitric acid or bromine, and concentrate to about 25 cc. Add -ammonium hydroxide in slight excess, boil one minute, and filter. -Dissolve the precipitate on the filter in a small amount of hot dilute -hydrochloric acid. Reprecipitate with ammonium hydroxide, filter, and -wash. Unless very accurate results are necessary this solution and -reprecipitation may be omitted. Unite the two filtrates for -determination of calcium. Ignite and weigh the precipitate. It will -comprise oxides of iron and aluminium and phosphate. If much phosphate -is present it should be determined in a separate sample and a correction -for the amount applied; otherwise it may be neglected. Determine the -iron in the ignited precipitate by fusion with sodium or potassium -pyrosulfate, reduction with zinc, and titration with potassium -permanganate. Aluminium (Al) is calculated as follows: - - Al = 0.53[(Fe_{2}O_{3} + Al_{2}O_{3}) − 1.43 Fe] - - - CALCIUM. - -Concentrate the filtrate from the separation of iron and aluminium to -about 100 cc., and add an excess of concentrated solution of ammonium -oxalate, little by little, to the hot ammoniacal solution. Keep the -solution warm and stir at intervals till the precipitate settles readily -and leaves a clear supernatant liquid. Filter, dissolve the precipitate -in a little hot dilute hydrochloric acid, and reprecipitate with -ammonium hydroxide and ammonium oxalate. If great accuracy is not -required this solution and reprecipitation may be omitted, and the first -precipitate may be washed clean with hot water[64a]. Save the filtrate -for determination of magnesium. Ignite the precipitate and weigh it as -calcium oxide, 71.5 per cent of which is the equivalent of calcium (Ca); -or dissolve the precipitate in hot 2 per cent sulfuric acid and titrate -with a standard solution of potassium permanganate. - - - MAGNESIUM. - -Acidify with hydrochloric acid the filtrate from the separation of -calcium and concentrate it to about 100 cc. Add 20 cc. of a saturated -solution of microcosmic salt, cool, and make slightly but distinctly -alkaline by adding ammonium hydroxide, drop by drop. Allow the solution -to stand four hours, then filter and wash with 3 per cent ammonium -hydroxide. Dissolve the precipitate, especially in the presence of large -amounts of sodium or potassium, in a slight excess of dilute -hydrochloric acid and reprecipitate the magnesium with ammonium -hydroxide and a few drops of microcosmic salt solution. If great -accuracy is not required this solution and reprecipitation may be -omitted. Ignite the precipitate and weigh it as magnesium pyrophosphate -(Mg_{2}P_{2}O_{7}), 21.9 per cent of which is the equivalent of -magnesium (Mg.). If manganese is present[64a] it is precipitated with -the magnesium and a correction for it should be applied after having -determined manganese in a separate sample. The weight of manganese -pyrophosphate (Mn_{2}P_{2}O_{7}) is 2.58 times the weight of manganese. - - - SEPARATION OF SULFATE, SODIUM, AND POTASSIUM. - - - SULFATE. - -Evaporate to dryness 100 to 1,000 cc. of the sample, or sufficient to -obtain a residue weighing 0.4 to 0.6 gram and containing preferably 0.05 -to 0.2 gram of sodium. Acidify the residue with hydrochloric acid and -remove the silica, iron, and aluminium (pp. 56–57). Make acid and add a -hot solution of barium chloride in slight excess to the hot filtrate, -and warm it, stirring at intervals for one-half hour, until the -precipitate settles readily and leaves a clear supernatant liquid. Dry, -ignite, and weigh the precipitate of barium sulfate, 41.1 per cent of -which is equal to the content of sulfate (SO_{4}). - - - SODIUM, POTASSIUM, AND LITHIUM. - -Evaporate to dryness the filtrate from the precipitation of barium -sulfate. Add a few cubic centimeters of hot water and then a saturated -solution of barium hydroxide until a slight film collects on the top of -the solution. Filter and wash the precipitate with hot water. Add to the -filtrate an excess of ammonium hydroxide and ammonium carbonate -solution. Filter, evaporate the filtrate to dryness, dry, and ignite at -low red heat to expel ammonium salts. Repeat the operations including -the addition of barium hydroxide until no precipitate is obtained by -barium hydroxide or by ammonium hydroxide and ammonium carbonate. -Evaporate the final filtrate to dryness in a weighed platinum dish, dry, -cool, and weigh the residue. Dissolve the residue in a few cubic -centimeters of water, filter, wash the filter paper twice with hot -water, then ignite the filter paper in the platinum dish. Cool and weigh -the residue. Subtract this weight from the first weight including the -residue. The difference is the weight of the chlorides of sodium and -potassium and lithium. If it is not desired to separate sodium and -potassium the weight of sodium and potassium as sodium may be calculated -from this difference by multiplying it by 0.394. - - - POTASSIUM. - -_First procedure._—Add to the solution of the chlorides of sodium and -potassium a few drops of dilute hydrochloric acid (1 to 3) and 1 cc. of -10 per cent platinic chloride (PtCl_{4}) for each 30 mg. of the combined -chlorides. Evaporate to a thick syrup on the water bath, then remove -dish and allow it to come to dryness at laboratory temperature. Treat -the residue cold with 80 per cent alcohol and filter. Wash the -precipitate with 80 per cent alcohol until the filtrate is no longer -colored. Dry the precipitate and dissolve it in hot water. Evaporate the -solution to dryness in a platinum dish and weigh it as potassium -platinic chloride (K_{2}PtCl_{6}). The weight of potassium (K) is 16.1 -per cent of this weight and the equivalent of potassium chloride (KCl) -is 30.7 per cent of this weight. Subtract the equivalent weight of -potassium chloride from the weight of the combined chlorides. The weight -of the sodium is 39.4 per cent of the difference. - -_Second procedure._[86][103a]—Add to the hot solution of the combined -chlorides 20 per cent perchloric acid (HClO_{4}) slightly in excess of -the amount required to combine with the bases. One cubic centimeter of -20 per cent perchloric acid is equivalent to 90 mg. of potassium. -Evaporate the solution to dryness, dissolve the residue in 10 cc. of hot -water and a small amount of perchloric acid, and again evaporate to -dryness. Repeat the addition of water, perchloric acid, and evaporation -until white fumes appear on evaporating to dryness. Add to the residue -25 cc. of 96 per cent alcohol containing 0.2 per cent of perchloric acid -(1 cc. of 20 per cent perchloric acid in 100 cc. of 98 per cent -alcohol). Break up the residue with a stirring rod. Decant the -supernatant liquid through a weighed Gooch crucible that has been washed -with 0.2 per cent perchloric acid in alcohol. If the precipitate is -unusually large dissolve it in hot water and repeat the evaporation with -perchloric acid. Wash the precipitate once by decantation with the 0.2 -per cent perchloric acid in alcohol, transfer the precipitate to the -crucible, and wash it several times with a 0.2 per cent perchloric acid -in alcohol. Dry the crucible at 120–130° C. for one hour, cool, and -weigh it. The increase in weight is potassium perchlorate (KClO_{4}). -The equivalent weight of potassium is 28.2 per cent and the equivalent -weight of potassium chloride is 53.8 per cent of the potassium -perchlorate. Calculate the content of sodium by difference. - - - LITHIUM.[34] - -Use a large quantity of the sample. Obtain the combined chlorides of -sodium, potassium, and lithium (see pp. 58–59). Transfer the combined -chlorides to a small Erlenmeyer flask (50 or 100 cc. capacity) and -evaporate the solution nearly, but not quite, to dryness. Add about 30 -cc. of redistilled amyl alcohol. Connect the flask, the stopper of which -carries a thermometer, with a condenser[E] and boil until the -temperature rises approximately to the boiling point of amyl alcohol -(130° C.), showing that all the water has been driven off. Cool slightly -and add a drop of hydrochloric acid to convert small amounts of lithium -hydroxide to lithium chloride. Connect with the condenser and continue -the boiling to drive off again all water and until the temperature -reaches the boiling point of amyl alcohol. The content of the flask at -this time is usually 15 to 20 cc. Filter through a small paper or a -Gooch crucible into a graduated cylinder and note exact quantity of -filtrate, which determines the subsequent correction. Wash the -precipitate with small quantities of dehydrated amyl alcohol. Evaporate -the filtrate and washings in a platinum dish to dryness on the steam -bath, dissolve the residue in water, and add a few drops of sulfuric -acid. Evaporate on a steam bath and expel the excess of sulfuric acid by -gentle heat over a flame. Repeat until carbonaceous matter is completely -burned off. Cool and weigh the dish and contents. Dissolve in a small -quantity of hot water, filter through a small filter, wash, and return -filter to dish, ignite, and weigh. The difference between the original -weight of dish and contents and the weight of the dish and small amount -of residue equals the weight of impure lithium sulfate. The purity of -the lithium sulfate should be tested by adding small amounts of ammonium -phosphate and ammonium hydroxide, which will precipitate any magnesium -present with the lithium sulfate. Any precipitate appearing after -standing over night should be collected on a small filter and weighed as -magnesium pyrophosphate, calculated to sulfate, and subtracted from the -weight of impure lithium sulfate. From this weight subtract 0.00113 gram -for every 10 cc. of amyl alcohol filtrate exclusive of the amyl alcohol -used in washing residue because of the slight solubility of solid mixed -chlorides in amyl alcohol. Calculate lithium from the corrected weight -of lithium sulfate. Dissolve the mixed chlorides from flask and filter -with hot water, evaporate to dryness, ignite gently to remove amyl -alcohol, filter and thoroughly wash; concentrate the filtrates and -washings to 25 to 50 cc. - -Footnote E: - - The amyl alcohol may be boiled off without the use of a condenser, but - the vapors are very disagreeable. - -To the weight of potassium chloride add 0.00051 gram for every 10 cc. of -amyl alcohol used in the extraction of the lithium chloride, which -corrects for the solubility of the potassium chloride in amyl alcohol. -Calculate to potassium. - -The weight of sodium chloride is found by subtracting the combined -weights of lithium chloride and potassium chloride (corrected) from the -total weight of the three chlorides. Calculate sodium chloride to -sodium. - - - BROMINE, IODINE, ARSENIC, AND BORIC ACID. - -Evaporate to dryness a large quantity of the sample to which a small -amount of sodium carbonate has been added. Boil the residue with -distilled water, transfer it to a filter, and thoroughly wash it with -hot water. Dilute the alkaline filtrate to a definite volume, and -determine bromine and iodine, arsenic, and boric acid in aliquot -portions of it. - - - BROMINE AND IODINE.[10] - -_Reagents._—1. Sulfuric acid. 1 to 5. - -2. Potassium nitrite or sodium nitrite. Two per cent solution. - -3. Carbon bisulfide. Freshly purified by distillation. - -4. Iodine standards. Acidify with dilute sulfuric acid measured -quantities of a standard solution of potassium iodide in small tubes. -Add 3 or 4 drops of the potassium nitrite solution and extract with -carbon bisulfide as in the actual determination. Transfer to small -flasks the standards from which the iodine has been removed. - -5. Chlorine water. Saturated solution. - -6. Bromine standards. Add measured quantities of a standard solution of -a bromide to the liquid in each of the small flasks from which the -iodine has been removed. Add to each 5 cc. of purified carbon bisulfide, -and proceed exactly as with the sample. - -_Procedure._—Evaporate to dryness an aliquot portion of the alkaline -filtrate. Dissolve the residue in 2 or 3 cc. of water, and add enough -absolute alcohol to make the percentage of alcohol about 90. Boil and -filter and repeat the extraction of the residue with alcohol once or -twice. Add 2 or 3 drops of sodium hydroxide to the combined alcoholic -filtrates and evaporate to dryness. Dissolve the residue in 2 or 3 cc. -of water and repeat the extraction with alcohol and the filtration. Add -a drop of sodium hydroxide to the filtrate and evaporate it to dryness. -Dissolve the residue in a little water. Acidify this solution with -dilute sulfuric acid, adding 3 or 4 drops excess, and transfer it to a -small flask. Add 4 drops of the solution of potassium nitrite or sodium -nitrite and about 5 cc. of carbon bisulfide. Shake the mixture until all -the iodine is extracted. Separate the acid solution from the carbon -bisulfide by filtration. Wash the flask, filter, and contents with cold -distilled water, and transfer the carbon bisulfide containing the iodine -in solution to Nessler tubes by means of about 5 cc. of pure carbon -bisulfide. In washing the filter, dilute the contents of the tube to a -definite volume, usually 12 or 15 cc., and compare the color with that -of known amounts of iodine dissolved in carbon bisulfide in other tubes. - -Transfer to a small flask the sample from which the iodine has been -removed. Add saturated chlorine water, 1 cc. at a time, shaking after -each addition until all the bromine is freed. Care must be taken not to -add much more chlorine than that necessary to free the bromine, since an -excess of reagent may form a bromochloride that spoils the color -reaction. Separate the water solution from the carbon bisulfide by -filtration through a moistened filter, wash the contents of the filter -two or three times with water, and then transfer them to a Nessler tube -by means of about 1 cc. of carbon bisulfide. Repeat this extraction of -the filtrate twice, using 3 cc. of carbon bisulfide each time. The -combined carbon bisulfide extracts usually amount to 11.5 to 12 cc. Add -enough carbon bisulfide to the tubes to bring them to a definite volume, -usually 12 to 15 cc., and compare the sample with the standards. If much -bromine is present it is not always completely extracted by the amounts -of carbon bisulfide recommended. If the extraction is incomplete, -therefore, make one or two extra extractions with carbon bisulfide, -transfer the extracts to another tube, and compare the color with that -of the standards. - - - ARSENIC.[31] - -Evaporate to dryness an aliquot portion of the alkaline filtrate (p. -61). Acidify the residue with arsenic-free sulfuric acid, and subject it -to the action of arsenic-free zinc and sulfuric acid in a -Marsh-Berzelius apparatus. Compare the mirror obtained with a mirror -obtained from an arsenious oxide solution of known strength. - - - BORIC ACID. - -Evaporate to dryness an aliquot portion of the alkaline filtrate (p. -61), treat the residue with 1 or 2 cc. of water, and slightly acidify -the solution with hydrochloric acid. Add about 25 cc. of absolute -alcohol, boil, filter, and repeat the extraction of the residue. Make -the filtrate slightly alkaline with sodium hydroxide, and evaporate it -to dryness. Add a little water, slightly acidify with hydrochloric acid, -and place a strip of turmeric paper in the liquid. Evaporate to dryness -on the steam bath, and continue the heating until the turmeric paper is -dry. If boric acid is present the turmeric paper becomes cherry red. It -is not usually necessary to determine quantitatively boric acid; the -quantitative method devised by Gooch[33] is recommended. - - - HYDROGEN SULFIDE.[103] - -Hydrogen sulfide should be determined preferably in the field; the -procedure as far as the final titration with sodium thiosulfate must be -carried out in the field. - -_Reagents._—1. N/100 sodium thiosulfate. - -2. Standard iodine. A N/100 solution containing potassium iodide -standardized against the N/100 sodium thiosulfate. To standardize, add -10 cc. of the iodine solution to 500 cc. of boiled distilled water. Add -about 1 gram of potassium iodide, and titrate with N/100 sodium -thiosulfate in the presence of starch indicator. One cc. of N/100 iodine -is equivalent to 0.17 mg. H_{2}S. - -3. Potassium iodide. Crystals. - -4. Starch. A freshly prepared solution for use as indicator. - -_Procedure._—Add 500 cc. of the sample to 10 cc. of the standard iodine -solution and 1 gram of potassium iodide in a large glass-stoppered -bottle or flask. If the sample is to be collected from a tap lead the -water into the bottle through a rubber tube extending to the bottom of -the bottle so as to eliminate errors due to aeration. Shake the bottle, -allow it to stand for a few minutes, and then titrate the excess of -iodine with sodium thiosulfate in the presence of starch indicator. -Hydrogen sulfide (H_{2}S) in parts per million is equal to 0.34 times -the difference in cubic centimeters between the amount of iodine -solution added and the amount of N/100 thiosulfate used in the -titration. - - - CHLORINE. - -In waters that have been treated with calcium hypochlorite or liquid -chlorine it is frequently advisable to ascertain the presence or absence -of chlorine. As the reagents which have been proposed for its detection -are not specific for chlorine but give similar or identical reactions -with oxidizing agents or reducible substances care must be exercised in -interpreting the results of such tests: nitrites and ferric salts are of -common occurrence, and chlorates also may lead to misinterpretation in -waters treated with calcium hypochlorite. - -_Reagents._—1. Tolidin solution. One gram of o-tolidin, purified by -being recrystallized from alcohol, is dissolved in 1 liter of 10 per -cent hydrochloric acid. - -2. Copper sulfate solution. Dissolve 1.5 grams of copper sulfate and 1 -cc. of concentrated sulfuric acid in distilled water and dilute the -solution to 100 cc. - -3. Potassium bichromate solution. Dissolve 0.025 gram of potassium -bichromate and 0.1 cc. of concentrated sulfuric acid in distilled water -and dilute the solution to 100 cc. - -_Procedure._—Mix 1 cc. of the tolidin reagent with 100 cc. of the sample -in a Nessler tube and allow the solution to stand at least 5 minutes. -Small amounts of free chlorine give a yellow and larger amounts an -orange color. - -For quantitative determination compare the color with that of standards -in similar tubes prepared from the solutions of copper sulfate and -potassium bichromate. The amounts of solution for various standards are -indicated in Table 13. - - Table 13.—PREPARATION OF PERMANENT STANDARDS FOR CONTENT OF CHLORINE. - - ───────────────────────┬───────────────────────┬─────────────────────── - Chlorine. │ Solution of copper │ Solution of potassium - │ sulfate. │ bichromate. - ───────────────────────┼───────────────────────┼─────────────────────── - _Parts per million._ │ _cc._ │ _cc._ - │ │ - 0.01│ 0.0│ 0.8 - .02│ .0│ 2.1 - .03│ .0│ 3.2 - .04│ .0│ 4.3 - .05│ .4│ 5.5 - .06│ .8│ 6.6 - .07│ 1.2│ 7.5 - .08│ 1.5│ 8.7 - .09│ 1.7│ 9.0 - .10│ 1.8│ 10.0 - .20│ 1.9│ 20.0 - .30│ 1.9│ 30.0 - .40│ 2.0│ 38.0 - .50│ 2.0│ 45.0 - ───────────────────────┴───────────────────────┴─────────────────────── - - - DISSOLVED OXYGEN.[16][65][68][71b][99][100c][120] - -_Reagents._—1. Sulfuric acid, concentrated. (Sp. gr. 1.83–1.84.) - -2. Potassium permanganate. Dissolve 6.32 grams of the salt in water and -dilute the solution to 1 liter. - -3. Potassium oxalate. A 2 per cent solution. - -4. Manganous sulfate. Dissolve 480 grams of the salt in water and dilute -the solution to 1 liter. - -5. Alkaline potassium iodide. Dissolve 700 grams of potassium hydroxide -and 150 grams of potassium iodide in water and dilute the solution to 1 -liter. - -6. Hydrochloric acid. Concentrated (Sp. gr. 1.18–1.19). - -7. Sodium thiosulfate. A N/40 solution. Dissolve 6.2 grams of chemically -pure recrystallized sodium thiosulfate in water and dilute the solution -to 1 liter with freshly boiled distilled water. Each cc. is equivalent -to 0.2 mg. of oxygen or to 0.1395 cc. of oxygen at 0°C. and 760 mm. -pressure. Inasmuch as this solution is not permanent it should be -standardized occasionally against a N/40 solution of potassium -bichromate. The keeping qualities of the thiosulfate solution are -improved by adding to each liter 5 cc. of chloroform and 1.5 grams of -ammonium carbonate before diluting to the prescribed volume. - -8. Starch solution. Mix a small amount of clean starch with cold water -until it becomes a thin paste and stir this mass into 150 to 200 times -its weight of boiling water. Boil for a few minutes, then sterilize. It -may be preserved by adding a few drops of chloroform. - -_Collection of sample._—Collect the sample in a narrow-necked -glass-stoppered bottle of 250 to 270 cc. capacity. The following -procedure should be followed in order to avoid entrainment or absorption -of atmospheric oxygen. In collecting from a tap fill the bottle through -a glass or rubber tube extending well into the tap and to the bottom of -the bottle. To avoid air bubbles allow the bottle to overflow for -several minutes, and then carefully replace the glass stopper so that no -air bubble is entrained. In collecting from the surface of a pond or -tank connect the sample bottle to a bottle of 1 liter capacity. Provide -each bottle with a two-hole rubber stopper having one glass tube -extending to the bottom and another glass tube entering but not -projecting into the bottle. Connect the short tube of the sample bottle -with the long tube of the liter bottle. Immerse the sample bottle in the -water and apply suction to the outlet of the liter bottle. To collect a -sample at any depth arrange the two bottles so that the outlet tube of -the liter bottle is at a higher elevation then the inlet tube of the -sample bottle. Lower the two bottles, in any convenient form of cage -properly weighted, to the desired depth. Water entering during the -descent will be flushed through into the liter bottle. When air bubbles -cease rising to the surface raise the bottles. Finally replace the -perforated stopper of the sample bottle with a glass stopper in such -manner as to avoid entraining bubbles of air. - -_Procedure._—Remove the stopper from the bottle and add, first, 0.7 cc. -of the concentrated sulfuric acid, and then 1 cc. of the potassium -permanganate solution. These and all other reagents should be introduced -by pipette under the surface of the liquid. Insert the stopper and mix -by inverting the bottle several times. After 20 minutes have elapsed -destroy the excess of permanganate by adding 1 cc. of the potassium -oxalate solution, the bottle being at once restoppered and its contents -mixed. If a noticeable excess of potassium permanganate is not present -at the end of 20 minutes, again add 1 cc. of the potassium permanganate -solution. If this is still insufficient use a stronger potassium -permanganate solution. After the liquid has been decolorized by the -addition of potassium oxalate add 1 cc. of the manganous sulfate -solution and 3 cc. of the alkaline potassium iodide solution. Allow the -precipitate to settle. Add 2 cc. of the hydrochloric acid and mix by -shaking. - -The procedure to this point must be carried out in the field, but after -the acid has been added and the stopper replaced there is no further -change, and the rest of the test may be performed within a few hours, as -convenient. Transfer 200 cc. of the contents of the bottle to a flask -and titrate with N/40 sodium thiosulfate, using a few cubic centimeters -of the starch solution as indicator toward the end of the titration. Do -not add the starch solution until the color has become faint yellow, and -titrate until the blue color disappears. - -The use of potassium permanganate is made necessary by high nitrite or -organic matter. The procedure outlined must be followed in all work on -sewage and partly purified effluents or seriously polluted streams or -samples whose nitrite nitrogen exceeds 0.1 part per million. In testing -other samples the procedure may be shortened by beginning with the -addition of the manganous sulfate solution and proceeding from that -point as outlined, except that only 1 cc. of alkaline potassium iodide -need be added. - -_Calculation of Results._—Oxygen shall be reported in parts per million -by weight. It is sometimes convenient to know the number of cubic -centimeters per liter of the gas at 0°C. temperature and 760 mm. -pressure and also to know the percentage which the amount of gas present -is of the maximum amount capable of being dissolved by distilled water -at the same temperature and pressure. If 200 cc. of the sample is taken -the number of cubic centimeters of N/40 thiosulfate used is equal to -parts per million of oxygen. Corrections for volume of reagents added -amount to less than 3 per cent and are not justified except in work of -unusual precision. To obtain the result in cubic centimeters per liter -multiply the number of cubic centimeters of thiosulfate used by 0.698. -To obtain the result in percentage of saturation divide the number of -cubic centimeters of thiosulfate by the figure in Table 14 opposite the -temperature of the water and under the proper chlorine figure. The last -column of Table 14 permits interpolation for intermediate chlorine -values. At elevations differing considerably from mean sea level and for -accurate work attention must be given to barometric pressure, the normal -pressure in the region being preferable to the specific pressure at the -time of sampling. The term “saturation” refers to a condition of -equilibrium between the solution and an oxygen pressure in the -atmosphere corresponding to 158.8 millimeters, or approximately -one-fifth atmosphere. The true saturation or equilibrium between the -solution and pure oxygen is nearly five times this value, and -consequently values in excess of 100 per cent saturation frequently -occur in the presence of oxygen-forming plants. - - Table 14.—SOLUBILITY OF OXYGEN IN FRESH WATER AND IN SEA WATER OF - STATED DEGREES OF SALINITY AT VARIOUS TEMPERATURES WHEN EXPOSED TO AN - ATMOSPHERE CONTAINING 20.9 PER CENT OF OXYGEN UNDER A PRESSURE OF 760 - MM.[F] - - (Calculated by G. C. Whipple and M. C. Whipple from measurements of C. - J. Fox.)[27][119] - - ─────────────┬────────────────────────────────────────────┬─────────── - │ │Difference - Temperature. │ Chloride in sea water (milligrams per │ per 100 - │ liter). │ parts of - │ │ chloride. - ─────────────┼────────┬────────┬────────┬────────┬────────┼─────────── - │ 0. │ 5000. │ 10000. │ 15000. │ 20000. │ - ─────────────┼────────┴────────┴────────┴────────┴────────┼─────────── - _°C._ │_Dissolved oxygen in milligrams per liter._ │_Parts per - │ │ million._ - 0│ 14.62│ 13.79│ 12.97│ 12.14│ 11.32│ 0.0165 - 1│ 14.23│ 13.41│ 12.61│ 11.82│ 11.03│ .0160 - 2│ 13.84│ 13.05│ 12.28│ 11.52│ 10.76│ .0154 - 3│ 13.48│ 12.72│ 11.98│ 11.24│ 10.50│ .0149 - 4│ 13.13│ 12.41│ 11.69│ 10.97│ 10.25│ .0144 - 5│ 12.80│ 12.09│ 11.39│ 10.70│ 10.01│ .0140 - │ │ │ │ │ │ - 6│ 12.48│ 11.79│ 11.12│ 10.45│ 9.78│ .0135 - 7│ 12.17│ 11.51│ 10.85│ 10.21│ 9.57│ .0130 - 8│ 11.87│ 11.24│ 10.61│ 9.98│ 9.36│ .0125 - 9│ 11.59│ 10.97│ 10.36│ 9.76│ 9.17│ .0121 - 10│ 11.33│ 10.73│ 10.13│ 9.55│ 8.98│ .0118 - │ │ │ │ │ │ - 11│ 11.08│ 10.49│ 9.92│ 9.35│ 8.80│ .0114 - 12│ 10.83│ 10.28│ 9.72│ 9.17│ 8.62│ .0110 - 13│ 10.60│ 10.05│ 9.52│ 8.98│ 8.46│ .0107 - 14│ 10.37│ 9.85│ 9.32│ 8.80│ 8.30│ .0104 - 15│ 10.15│ 9.65│ 9.14│ 8.63│ 8.14│ .0100 - │ │ │ │ │ │ - 16│ 9.95│ 9.46│ 8.96│ 8.47│ 7.99│ .0098 - 17│ 9.74│ 9.26│ 8.78│ 8.30│ 7.84│ .0095 - 18│ 9.54│ 9.07│ 8.62│ 8.15│ 7.70│ .0092 - 19│ 9.35│ 8.89│ 8.45│ 8.00│ 7.56│ .0089 - 20│ 9.17│ 8.73│ 8.30│ 7.86│ 7.42│ .0088 - │ │ │ │ │ │ - 21│ 8.99│ 8.57│ 8.14│ 7.71│ 7.28│ .0086 - 22│ 8.83│ 8.42│ 7.99│ 7.57│ 7.14│ .0085 - 23│ 8.68│ 8.27│ 7.85│ 7.43│ 7.00│ .0083 - 24│ 8.53│ 8.12│ 7.71│ 7.30│ 6.87│ .0083 - 25│ 8.38│ 7.96│ 7.56│ 7.15│ 6.74│ .0082 - │ │ │ │ │ │ - 26│ 8.22│ 7.81│ 7.42│ 7.02│ 6.61│ .0080 - 27│ 8.07│ 7.67│ 7.28│ 6.88│ 6.49│ .0079 - 28│ 7.92│ 7.53│ 7.14│ 6.75│ 6.37│ .0078 - 29│ 7.77│ 7.39│ 7.00│ 6.62│ 6.25│ .0076 - 30│ 7.63│ 7.25│ 6.86│ 6.49│ 6.13│ .0075 - ─────────────┴────────┴────────┴────────┴────────┴────────┴─────────── - -Footnote F: - - Under any other barometric pressure, B, the solubility can be obtained - from the corresponding value in the table by the formula: - - S´ = S(B/760) = S(B´/29.92) in which S´ = Solubility at B or B´, - S = Solubility at 760 mm. or 29.92 - inches, - B = Barometric pressure in mm., - and B´ = Barometric pressure in - inches. - - - ETHER-SOLUBLE MATTER.[44] - -Evaporate 500 cc. of the sample in a porcelain evaporating dish to a -volume of about 50 cc. By means of a rubber-tipped glass rod remove to -the bottom of the dish the solid matter attached to the sides, and add -normal sulfuric acid to neutralize the alkalinity. Do not use an excess -of acid. Then evaporate the contents of the dish to dryness. Treat the -dry residue with boiling ether, rubbing the bottom and sides of the dish -to insure complete solution of fat. Three extractions with ether are -required. Filter the ether solution through a 5 cm. filter into a -weighed flask having a wide mouth. Evaporate the ether slowly, and dry -the flask at 100° C. for 30 minutes. The increase in weight of the flask -gives the amount of fats, or, in more precise language, the -ether-soluble matter. - -An excess of acid gives too high results because of the formation of -fatty-acid residues. - - - RELATIVE STABILITY OF EFFLUENTS.[78] - -_Reagent._—Methylene blue solution. A 0.05 per cent aqueous solution of -methylene blue, preferably the double zinc salt or commercial -variety.[60b] - -_Collection of sample._—Collect the sample in a glass-stoppered bottle -holding approximately 150 cc. If the dissolved oxygen is low observe -precautions similar to those used in collecting samples for dissolved -oxygen (p. 66). - -_Procedure._—Add 0.4 cc. of the methylene blue solution to the sample in -the 150 cc. bottle. As methylene blue has a slightly antiseptic property -be careful to add exactly 0.4 cc. Add the methylene blue solution -preferably below the surface of the liquid after filling the bottle with -the sample. If the methylene blue is added first do not allow the liquid -to overflow as coloring matter will thus be lost. Incubate the sample at -20° C. for ten days. Four days’ incubation may be considered sufficient -for all practical purposes in routine plant-control work. If quick -results are desired incubate the sample at 37° C. for five days using -suitable stoppers[1a][2a] to prevent the loss and reabsorption of -dissolved oxygen. The bacterial flora at 37° C. is different from that -at 20° C. The lower temperature is more nearly the average temperature -of surface waters and therefore the higher temperature should be used -only when quick approximate results are essential. Observe the sample at -least twice a day during incubation. Give a sample in which the -methylene blue becomes decolorized a relative stability corresponding to -the time required for reduction (see Table 15). For routine filter -control ordinary room or cellar temperature gives fairly satisfactory -results. For accurate studies, room temperature incubation is very -undesirable, as the fluctuations in temperature which are ordinarily not -noticed are responsible for appreciable deviations from the true values -of relative stability. If the samples are incubated less than 10 days at -20° C. and are not decolorized place a plus sign after the stability -value in order to indicate that the stability might have been higher if -more time had been allowed. In applying this test to river waters it -often happens that the blue coloring matter is removed either partly or -completely through absorption by the clay which many rivers carry in -suspension. True relative stabilities cannot be obtained for such waters -except by determining the initial available oxygen at the start and the -biochemical oxygen demand on incubation at 20° C. for 10 days (pp. -71–73). Germicides, such as hypochlorite of lime, if present in -sufficient quantity, vitiate the results. If a sample contains free -chlorine, therefore, store it about 2 hours, or until the chlorine is -gone, and then add methylene blue. - -Table 15[78] gives the relation between the time in days to decolorize -methylene blue at 20° C. (_t__{20}) and the relative stability number or -ratio of available oxygen to oxygen required for equilibrium, expressed -in percentage (S). - - Table 15.—RELATIVE STABILITY NUMBERS. - - ───────────────────────────────────┬─────────────────────────────────── - Time required for decolorization at│ Relative stability. - 20° C. │ - ───────────────────────────────────┼─────────────────────────────────── - _Days._ │ _Percentage._ - 0.5│ 11 - 1.0│ 21 - 1.5│ 30 - 2.0│ 37 - 2.5│ 44 - 3.0│ 50 - 4.0│ 60 - 5.0│ 68 - 6.0│ 75 - 7.0│ 80 - 8.0│ 84 - 9.0│ 87 - 10.0│ 90 - 11.0│ 92 - 12.0│ 94 - 13.0│ 95 - 14.0│ 96 - 16.0│ 97 - 18.0│ 98 - 20.0│ 99 - ───────────────────────────────────┴─────────────────────────────────── - -The theoretical relation is, S = 100 (1 − 0.794_t__{20}) - -The relation between the time of reduction at 20° C. and that at 37° C. -is approximately two to one, but if an observer incubates at 37° C. he -should work out his own comparative 37° C. table or factor. - -A relative stability of 75 signifies that the sample examined contains a -supply of available oxygen equal to 75 per cent of the amount of oxygen -which it requires in order to become perfectly stable. The available -oxygen is approximately equivalent to the dissolved oxygen plus the -available oxygen of nitrate and nitrite. Nitrite in sewage is usually so -low as to be negligible. - - - BIOCHEMICAL OXYGEN DEMAND OF SEWAGE AND EFFLUENTS.[60a][60c][60d] - - - RELATIVE STABILITY METHOD. - -The relative stability method may be employed to obtain a measure of the -putrescible material in sewages and effluents in terms of oxygen demand. - -_Procedure for effluents._—Divide the total available oxygen, including -the oxygen of nitrite and nitrate, by the relative stability expressed -as a decimal. - -_Procedure for sewages._—Make one or two dilutions with fully aerated -distilled water of known dissolved oxygen content. Tap water may be -employed if it is free from nitrates. Vary the relative proportions of -sewage and water to be employed to give a relative stability of 50 to -75. Unless seals[1b][2b][52a] are used bring the water as well as the -sewage to the temperature at which the mixtures are to be incubated -before preparing the dilutions. During the manipulation avoid aeration. -Having made the proper dilutions, determine the relative stability of -each. - -Calculate the oxygen demand in parts per million by the formula: - - Oxygen demand = O(1 − p)/Rp - -In this formula, O is the initial dissolved oxygen of the diluting -water, p is the proportion of sewage; and R is the relative stability of -the mixture. Ordinarily the available oxygen in crude sewages, septic -tank effluents, settling tank effluents, and trade wastes can be -neglected. - - - SODIUM NITRATE METHOD. - -For the determination of the biochemical oxygen demand the sodium -nitrate method may be used[60a][60c][60d][52a]. The method is based on -the biochemical consumption of oxygen from sodium nitrate by a sewage or -polluted water during an incubation period of ten days at 20° C. A -reasonable excess of sodium nitrate does not give a higher oxygen -demand, as do higher dilutions with aerated water. The oxygen absorbed -from the air in applying the method to sewages is negligible. - -_Reagent._—Sodium nitrate solution. Dissolve 26.56 grams of pure sodium -nitrate in 1 liter of distilled water. One cc. of this solution in 250 -cc. of sewage represents 50 parts per million of available oxygen. The -strength of the sodium nitrate solution may be varied to suit -conditions. - -_Procedure for sewages._—Ordinarily disregard the initial available -oxygen as it is very small compared with the total biochemical oxygen -demand. Add measured amounts of the sodium nitrate solution to the -sewage in bottles holding approximately 250 cc. which have been -completely filled and stoppered. Incubate for 10 days at 20° C. A seal -is not required during incubation. The appearance of a black sediment -and the development of a putrid odor during incubation indicates that -too little sodium nitrate has been added. Methylene blue solution in -proper proportion may be added at the start to serve as an indicator -during the incubation. Domestic sewage usually varies in its oxygen -demand from 100 to 300 parts per million, approximately 30 per cent of -which is used up at 20° C. in the first 24 hours. At the end of the -incubation period determine the residual nitrite and nitrate. Determine -the nitrate by the aluminium reduction method and direct Nesslerization. -To convert the nitrogen into oxygen equivalents, multiply the nitrite -nitrogen by 1.7 and the nitrate nitrogen by 2.9. The difference between -the available oxygen added as sodium nitrate and that found as nitrite -and nitrate at the end of the incubation period is the biochemical -oxygen demand. - -_Procedure for industrial wastes._—Employ the same procedure using -larger quantities of the sodium nitrate solution. Make the reaction -alkaline to methyl orange and acid to phenolphthalein. Adjust an acid -reaction with sodium bicarbonate and a caustic alkaline reaction with -weak hydrochloric acid. If the liquid is devoid of sewage bacteria seed -it with sewage after adjusting the reaction. - -_Procedure for polluted river waters._—Determine the initial available -oxygen. Unless the river water is badly polluted add 10 parts per -million of sodium nitrate oxygen. Collect carefully, avoiding aeration, -three samples in 250 cc. bottles. To one sample add a definite quantity -of sodium nitrate solution and incubate. Incubate the other two samples -for the determination of the residual free oxygen, nitrite, and nitrate. -If there is free oxygen left, the bottle containing the sodium nitrate -solution may be discarded. If there is no free oxygen determine residual -nitrite and nitrate as directed under the procedure for sewage (p. 72) -and calculate the oxygen demand. - - - - - ANALYSIS OF SEWAGE SLUDGE AND MUD DEPOSITS. - - - COLLECTION OF SAMPLE. - -Collect a representative sample of the material. In general more than -one sample should be taken from a spot and a large number of samples -should be collected rather than a few large samples. If the surface -layer is darker and a lower layer consists of pure clay sample only the -surface layer. Samples may be analyzed either separately or as -composites of careful mixtures. After the sample has settled a few -minutes roughly drain or siphon the excess water. Allow sewage sludge to -stand for one hour before draining it free from excess water unless it -is essential to determine the moisture content of the sample originally -collected. If sludge cannot be analyzed within twenty-four hours it is -better not to use air-tight bottles and to add small quantities of -chloroform and keep in the ice box to retard decomposition. At the time -of collection carefully examine mud from the bottom of surface water for -evidence of sewage pollution and macroscopic and microscopic animal and -plant organisms. Record the predominant species. Note the physical -appearance of the material, particularly its color, odor, and -consistency. Express all analytical results in percentage on a dry -basis. - - - REACTION. - -Determine the reaction by diluting a definite quantity of the wet sludge -and titrating by the methods given under alkalinity and acidity (pp. -35–39 and 39–41). - - - SPECIFIC GRAVITY. - -Weigh to the nearest tenth of a gram a wide-mouthed flask of 100 to 300 -cc. capacity, according to the quantity of material available. Then -completely fill the flask with distilled water to the brim and weigh it -again. Empty the flask and fill it completely with fresh sewage sludge -or mud. If the material is of such consistency that it flows readily -fill the flask to the brim and weigh. The specific gravity is equal to -the weight of the sludge or mud divided by the weight of an equal volume -of distilled water. - -If the material does not flow readily fill the weighed flask as -completely as possible without exerting pressure during the procedure. -Weigh and then fill the flask to the brim with distilled water. Let it -stand for a few minutes, until trapped air has escaped, then add more -water if necessary and weigh. Subtract the weight of the added water -from the weight of the water that completely fills the flask; the -specific gravity is equal to the weight of the material divided by this -difference. Record the specific gravity only to the second decimal -place. - - - MOISTURE. - -Heat approximately 25 grams of sludge or mud in a weighed nickel dish on -the water bath until it is fairly dry. Dry the residue in an oven at -100° C., cool, and weigh. Repeat to approximate constant weight. The -loss in weight is moisture. - - - VOLATILE AND FIXED MATTER. - -Ignite, at dull red heat in a hood, the residue from the determination -of moisture until all the carbon has disappeared. Cool the residue in a -desiccator and weigh it. The residue is the fixed matter. The volatile -matter is the difference in weight between the original dried sludge and -the ignited sludge. - - - TOTAL ORGANIC NITROGEN. - -_Preparation of sample._—For the determination of organic nitrogen and -fats dry approximately 50 to 75 grams of the sludge or mud in a -porcelain dish first on the water bath and finally in the hot-water oven -until all the moisture has disappeared. Grind the dry material to a fine -powder and keep it in a glass-stoppered bottle. - - _Reagents._—1. Sulfuric acid. Concentrated, nitrogen-free. - 2. Copper sulfate solution. Ten per cent. - 3. Potassium permanganate. Crystals. - -_First procedure._—Weigh accurately 0.5 gram of dried sludge or 5.0 -grams of dried mud and put it into a 500 cc. Kjeldahl flask. Digest it -with 20 cc. of sulfuric acid, or more if necessary, and 1 cc. of copper -sulfate solution to assist the oxidation. Boil for several hours until -the liquid becomes colorless or slightly yellow. Oxidize the residue -with 0.5 gram of potassium permanganate, and follow the “Procedure for -Sewage” (pp. 21–22). - -_Second procedure._—The following method is convenient for routine work -at sewage disposal plants. After digestion as described in the first -procedure, cool, transfer to a glass-stoppered 100 cc. flask, dilute -with distilled water to 100 cc., and mix well. Transfer 50 cc. with a -pipette into another 100 cc. volumetric flask, and make this portion -alkaline with 50 per cent sodium hydroxide, testing a drop of the liquid -on a porcelain plate with phenolphthalein to insure neutralization. The -formation of a floc usually indicates that neutralization is complete. -Dilute the solution to 100 cc., pour it into a small glass-stoppered -bottle and permit it to stand until the next day. Nesslerize an aliquot -portion of the clear supernatant liquid, and calculate the percentage of -nitrogen in the material. - - - ETHER-SOLUBLE MATTER. - -Fats are usually determined only on sewage sludge, but some mud deposits -contain small quantities due to the presence of trade wastes. - -_Procedure._—Weigh 0.5 to 25 grams of dry material according to the -quality of the sludge or mud. Add water to the weighed portion in a -porcelain dish and acidify the mixture with N/50 sulfuric acid in the -presence of litmus tincture or azolitmin solution as indicator. Avoid -adding too much acid as an excess gives too high results on account of -fatty acid residues. Evaporate the acidified mixture to dryness on the -water bath, and heat it in the hot air oven at 100° C. two to three -hours. Extract the dry residue with boiling ether, rubbing the sides and -bottom of the dish to insure complete solution of the fat. Three -extractions with ether are usually sufficient. Filter the ether solution -through a 5 cm. filter paper into a small flask. Evaporate the ether -slowly, dry the fatty extract for half an hour at 100° C., cool in a -desiccator, and weigh. If it is desirable, particularly with certain -industrial wastes, to determine the quantity of saponified fat determine -the fats with and without the addition of acid. The difference between -the quantities found by the two determinations is the content of -saponified fat. - - - FERROUS SULFIDE. - -The liberation of hydrogen sulfide on adding dilute hydrochloric acid to -a sludge indicates the presence of ferrous sulfide. As ferrous sulfide -quickly oxidizes on exposure to air a quantitative determination of this -constituent must be made immediately after collection of the sample. - -_Procedure._—Heat a definite portion of the sludge with hydrochloric -acid in a flask. Pass the liberated gas through bromine water or -hydrogen peroxide. Determine gravimetrically the sulfate in the -oxidizing solution, and calculate the equivalent of ferrous sulfide by -multiplying the weight of barium sulfate by 0.376. - - - BIOCHEMICAL OXYGEN DEMAND. - -The quantity of river mud most suitable for the determination of the -biochemical oxygen demand ranges within certain limits, largely -according to the amount of oxidizable matter present. For examinations -of river mud prepare a 1 per cent stock suspension in distilled water or -tap water saturated with oxygen and free from nitrate; use in the test a -dilution of this stock suspension equivalent to a concentration of 1 to -10 grams per liter of mud. For examinations of fresh sewage sludge -prepare a 1 per cent stock suspension in a similar manner, but use in -the test a dilution equivalent to only 0.1 to 1.0 gram per liter of wet -material. For examinations of dried sludges, which have undergone more -or less oxidation higher concentrations may be required. - -_Procedure._—Place a measured portion of the sample, or the proper -amount of the 1 per cent stock suspension of the sample, in a 300 cc. -narrow-mouth glass-stoppered bottle, and dilute it to the desired -concentration with water saturated with oxygen. Determine the oxygen -content at 20° C. of the waters that are used for dilution. This -determination must be made before the mud or sludge is added because -iron sulfide in the mud or sludge rapidly consumes part of the dissolved -oxygen. Incubate at 20° C. for five days. - -Shortly before the determination of the oxygen remaining in solution at -the end of five days rotate the bottle once or twice to mix its contents -and allow sedimentation for about 30 minutes. Siphon the greater part of -the liquid through a narrow-bore siphon into a 150 cc. bottle, which has -been filled with carbon dioxide. Reject the first 25 cc. of the siphoned -liquid and allow a little to overflow at the end of siphoning. Determine -the oxygen content of the solution in the bottle in the usual way (pp. -65–68). Report the oxygen demand in percentage of the dried mud or -sludge. - - - - - ANALYSIS OF CHEMICALS. - - -The following sections describe the accepted methods for the analysis of -the chemicals commonly used in the treatment of water. - - - REAGENTS. - -1. Distilled water. In practically all the tests of chemicals it is -necessary to use exclusively distilled water that has been freshly -boiled to free it from carbon dioxide and oxygen. - -2. Concentrated hydrochloric acid. Sp. gr. 1.20. - -3. Hydrochloric acid, N/2. - -4. Hydrochloric acid, N/10. - -5. Ammonium hydroxide. Redistilled; sp. gr. 0.90. - -6. Dilute sulfuric acid. Dilute 1 part of concentrated sulfuric acid -with 3 parts of freshly boiled distilled water. - -7. Methyl orange indicator. See page 36. - -8. Phenolphthalein indicator. See page 36. - -9. Bromine water. - -10. Stannous chloride, N/20. This should be frequently standardized by -titration against a standard iron solution. One cc. of N/20 stannous -chloride is equal to 0.0028 gram of iron (Fe) estimated in the ferrous -state. - -11. Sodium hydroxide, N/1. Free from carbonate. This should be -frequently standardized by titration against a standard acid solution in -presence of phenolphthalein indicator. One cc. of N/1 sodium hydroxide -is equal to 0.049 gram of sulfuric acid (H_{2}SO_{4}), or to 0.03645 -gram of hydrochloric acid (HCl). - -12. Sodium hydroxide, N/20. Free from carbonate. - -13. Standard potassium permanganate. A N/10 solution. One cc. of N/10 -potassium permanganate is equal to 0.0056 gram of iron (Fe) estimated in -the ferrous state. - -14. Alcohol. Ethyl alcohol, 95 per cent. - -15. Sugar. Solid granulated cane sugar. - - - SULFATE OF ALUMINIUM. - -Determine and report insoluble matter, aluminium oxide (Al_{2}O_{3}), -ferric oxide (Fe_{2}O_{3}), ferrous oxide (FeO), basicity ratio, and, if -present, free acid as H_{2}SO_{4}. If the material is what is known as -“granular” sulfate mix it well before sampling. If it is in lump form -crush it to ⅛ to ¼ inch size, mix, and sample it. It is unnecessary to -grind the sample to a fine powder, but it is preferable to have the -particles fairly uniform in size. - - - INSOLUBLE MATTER. - -Treat 10 grams of the sample with 100 cc. of distilled water and digest -one hour at boiling temperature. Filter through a weighed Gooch crucible -and wash the insoluble matter with hot water freshly boiled to free it -from carbon dioxide. Dry the crucible to constant weight at 100° C., -cool, and weigh. Report the percentage of insoluble matter. - - - OXIDES OF IRON AND ALUMINIUM. - -Dilute the filtrate from the determination of insoluble matter to 500 -cc. with water free from carbon dioxide and thoroughly mix the solution. -Transfer 50 cc. of the solution to a 250 cc. beaker, add about 150 cc. -of water and 5 cc. of concentrated hydrochloric acid, and heat to -boiling. Add ammonium hydroxide in slight excess; when the solution has -been almost neutralized it is convenient to add a drop of methyl orange -indicator and then to add about 0.5 cc. of ammonium hydroxide after the -solution is neutral to the indicator. Digest at about 100° C. for a few -minutes and filter. Some analysts prefer to wash this gelatinous -precipitate with hot water by decantation, and some to wash it evenly -distributed over the surface of a filter paper; either method may be -used. It is difficult to free it completely from impurities and it is -not necessary to do so unless unusual quantities of calcium, magnesium, -sodium, or potassium are present. While the precipitate is being washed -do not allow it to become dry, as it then packs and can not be washed -clean. After most of the water has drained drying the filter may be -hastened by placing it on a sheet of blotting paper. If much iron is -present completely dry the precipitate, remove it from the paper, and -ignite the paper separately. Finally, blast the precipitate, with free -access of air to the crucible, for five or ten minutes, cool, and weigh -as oxides of iron and aluminium (Fe_{2}O_{3} + Al_{2}O_{3}). - -Subtract the content of total iron, expressed as ferric oxide -(Fe_{2}O_{3}), from the weight of the combined oxides and report the -difference as aluminium oxide (Al_{2}O_{3}), in percentage. - - - TOTAL IRON. - -As filter alum usually contains 0.2 to 0.3 per cent of iron use a 10 -gram sample for the determination of total iron. Treat the sample with -50 cc. of freshly boiled distilled water and add 5 cc. of concentrated -hydrochloric acid and 1 cc. of bromine water. Evaporate the solution to -dryness, dissolve the residue in water, and wash it into a flask with -sufficient water to make the volume about 50 cc. Add 50 cc. of -concentrated hydrochloric acid, boil to expel oxygen, and titrate, as -hot as possible, with N/20 stannous chloride. - -If a 10 gram sample is used the percentage of iron (Fe) is equal to the -number of cubic centimeters of stannous chloride used multiplied by -0.028, and the percentage of iron expressed as ferric oxide is equal to -the number of cubic centimeters of stannous chloride used multiplied by -0.040. - - - FERRIC IRON. - -As filter alum usually contains 0.02 to 0.04 per cent of ferric iron use -a 20 gram sample. Boil 50 cc. of distilled water to expel oxygen, add 50 -cc. of concentrated hydrochloric acid, and add the sample while the -solution is boiling. Keep it boiling till the sample is dissolved. The -flask should be kept filled with carbon dioxide during this process by -dropping in occasionally small amounts of sodium carbonate. When -solution of the sample is complete titrate it hot immediately with N/20 -stannous chloride. - -If a 20 gram sample is used the percentage of ferric oxide (Fe_{2}O_{3}) -is equal to the number of cubic centimeters of stannous chloride used -multiplied by 0.020. - - - FERROUS IRON. - -The content of ferrous iron is the difference between total and ferric -iron. The percentage of ferrous oxide (FeO) is, therefore, equal to 0.90 -times the difference between the percentage of total iron expressed as -ferric oxide and the percentage of ferric iron expressed as ferric -oxide. Report the percentage of ferrous oxide (FeO). - - - BASICITY RATIO. - -Transfer 50 cc. of the filtrate from the determination of insoluble -matter to a 200 cc. casserole and dilute it to 100 cc. Boil the solution -and titrate it at boiling temperature with N/1 sodium hydroxide in -presence of phenolphthalein indicator. The percentage of acidity in -equivalent of sulfuric acid (H_{2}SO_{4}) is equal to the number of -cubic centimeters of sodium hydroxide used multiplied by 4.9. In this -titration iron and aluminium are precipitated as hydroxides and any free -acid is neutralized. - -Calculate the percentage of sulfuric acid equivalent to the determined -percentages of aluminium oxide, ferric oxide, and ferrous oxide by the -following formula: - - 2.88 Al_{2}O_{3} + 1.83 Fe_{2}O_{3} + 1.36 FeO. - -If this percentage of acid equivalent is less than that found by -titration report the difference as percentage of free acid. If the -percentage of acid equivalent is greater than that found by titration -the difference divided by 2.88 is the percentage equivalent to the -excess of aluminium oxide present. Divide this excess by the percentage -of total aluminium oxide and report the quotient as the basicity ratio. - - - LIME. - -Mix well the sample, which should contain no lumps. If foreign matter is -present grind the sample to pass a 100–mesh sieve. - -Place 20 grams of granulated cane sugar and 1 gram of the sample in a -250 cc. glass-stoppered bottle, tightly stopped, and mix the mass by -rolling. Do not shake hard as much of the lime could thus be lost as -dust. Then add 187.4 cc. of distilled water freshly boiled to expel -carbon dioxide. This makes 200 cc. of sugar solution. The lime is mixed -dry with the sugar and the water added later to keep the lime from -lumping. After shaking the sugar solution one hour titrate 50 cc. of it -with N/2 hydrochloric acid in presence of methyl orange indicator. The -acid used is equivalent to the carbonate and hydroxide in 0.25 gram of -the sample. - -Filter the remainder of the sugar solution, discarding the first 25 cc. -of filtrate. Titrate 50 cc. of the filtrate with N/2 hydrochloric acid -in presence of methyl orange indicator. The acid used is equivalent to -the hydroxide in 0.25 gram of the sample. - -If a 1 gram sample is used the percentage of calcium oxide (CaO) is -equal to 5.6 times the number of cubic centimeters of hydrochloric acid -used in the second titration; and the percentage of calcium carbonate -(CaCO_{3}) equivalent to the carbonate present is equal to 10 times the -difference in cubic centimeters between the results of the two -titrations. - - - SULFATE OF IRON. - - - INSOLUBLE MATTER. - -Treat 10 grams of the sample with 100 cc. of freshly boiled distilled -water cooled to 30° C. or less. When solution is complete filter through -a weighed Gooch crucible, wash, dry, cool, and weigh. Report the weight -of the residue, in percentage, as insoluble matter. - - - IRON AS FERROUS SULFATE. - -Dissolve 1 gram of the sample and dilute to 200 cc. with freshly boiled -distilled water cooled to 30° C. or less. Add 5 cc. of dilute sulfuric -acid (1 to 3) to a 50 cc. portion of the solution and titrate with N/10 -potassium permanganate. The percentage of ferrous sulfate -(FeSO_{4}.7H_{2}O) is equal to 11.12 times the number of cubic -centimeters of potassium permanganate used. - - - ACIDITY. - -Shake 12.25 grams of the sample in a 150 cc. bottle with 75 cc. of 95 -per cent alcohol for ten minutes. Run a blank. Filter rapidly both -sample and blank and wash rapidly with alcohol sufficient to make 100 -cc. of filtrate. Titrate with N/20 sodium hydroxide in presence of -phenolphthalein and subtract the result of titrating the blank from that -of titrating the solution of the sample. The percentage of acidity, -expressed as sulfuric acid (H_{2}SO_{4}), is equal to 0.02 times the -number of cubic centimeters of sodium hydroxide used. - - - SODA ASH. - - - INSOLUBLE MATTER. - -Treat 5.305 grams of the sample with 200 cc. of freshly boiled and -cooled distilled water. When solution is complete filter through an -asbestos mat in a weighed Gooch crucible, dry, cool, and weigh. Report -the weight of the residue, in percentage, as insoluble matter. - - - AVAILABLE ALKALI. - -Dilute the filtrate from the determination of insoluble matter to 1,000 -cc. and thoroughly mix. Titrate 25 cc. of this dilution with N/10 -hydrochloric acid in presence of methyl orange indicator. The percentage -of available alkali, expressed as sodium carbonate (Na_{2}CO_{3}), is -equal to 4 times the number of cubic centimeters of hydrochloric acid -used. - - - - - CHEMICAL BIBLIOGRAPHY. - - -The subjoined bibliography comprises the publications cited in the text -of this report. The references are arranged alphabetically by authors’ -names and under each author in order of dates of publication. When -different pages of a single work are cited letters are used in -connection with the number that refers to the work. - -Bibliography 1: - - ANDREWS, L. W. Sprengel’s method for colorimetric determination of - nitrates: _J. Am. Chem. Soc._, Vol. 26, pp. 388–91, 1904. - -Bibliography 1a: - - _a._ ASSOC. OFF. AG. CHEMISTS. Determination of iodine and bromine: - _J. A. O. A. C._, Vol. 1, No. 4, pt. 1, pp. 47–8, 1916. - -Bibliography 1b: - - _b._ BACHMANN, FRANK. A new seal for the prevention of aeration in - deaerated liquids: _J. Ind. Eng. Chem._, Vol. 6, pp. 764–5, 1914. - -Bibliography 2: - - BARTOW, EDWARD, and RODGERS, J. S. Determination of nitrates by - reduction with aluminium: _Am. J. Public Hygiene_, new ser., Vol. 5, - pp. 536–44, 1909; also _Illinois Univ. Bull._, Vol. 7, No. 2 (Water - Survey Ser. No. 7), pp. 14–27, 1909. - -Bibliography 2a: - - _a._ BLINN, WILLIAM. Determination of manganese as sulfate and by the - sodium bismuthate method: _J. Am. Chem. Soc._, Vol. 34, pp. 1379–98, - 1912. - -Bibliography 2b: - - _b._ BUSWELL, A. M. Modified apparatus for the putrescibility test: - _J. Ind. Eng. Chem._, Vol. 6, p. 325, 1914. - -Bibliography 3: - - CALDWELL, G. C. A method in part for the sanitary examination of water - and for the statement of results, offered for general adoption: _J. - Anal. Chem._, Vol. 3, pp. 398–403, 1889. - -Bibliography 4: - - CALKINS, G. N. A study of odors observed in the drinking waters of - Massachusetts: _Report Mass. State Board of Health_, pp. 355–80, 1892. - -Bibliography 5: - - CHAMOT, E. M., and PRATT, D. S. A study on the phenoldisulfonic acid - method for the determination of nitrates in water: _J. Am. Chem. - Soc._, Vol. 31, pp. 922–8, 1909; Vol. 32, pp. 630–7, 1910; and - REDFIELD, H. W., Vol. 33, pp. 366–81, 381–4, 1911. - -Bibliography 6: - - CLARK, H. W. Experiments upon the purification of sewage and water at - the Lawrence Experiment Station: _Report Mass. State Board of Health_, - pp. 427–578, 1896. - -Bibliography 7: - - CLARK, H. W., and FORBES, F. B. Methods for the determination of lead, - tin, zinc, and copper in drinking waters: _Report Mass. State Board of - Health_, pp. 577–85, 1898; pp. 498–506, 1900. - -Bibliography 8: - - COHN, A. I. Tests and reagents, 1st ed., p. 216, John Wiley & Sons, - New York, 1903. - -Bibliography 9: - - DIBDIN, W. J. The purification of sewage and water, 3d ed., pp. - 345–51, D. Van Nostrand Co., New York, 1903. - -Bibliography 10: - - DOLE, R. B. The quality of the surface waters in the United States: - _U. S. Geol. Survey Water-Supply Paper_ 236, pp. 15–9, 1909. - -Bibliography 11: - - DRAPER, H. N. Lacmoid and carminic acid as reagents for alkalies: - _Chem. News_, Vol. 51, pp. 206–7, 1885. - -Bibliography 13: - - DROWN, T. M., and MARTIN, HENRY. Determination of organic nitrogen in - natural waters by the Kjeldahl method: _Tech. Quart._, Vol. 2, No. 3; - _Chem. News_, Vol. 59, pp. 272–6, 1889. - -Bibliography 14: - - DROWN, T. M. The chemical examination of waters and the interpretation - of analyses: _Examinations by the State Board of Health of water - supplies of Mass. 1887–90_, pt. 1, Examination of water supplies, pp. - 519–78, 1890. - -Bibliography 15: - - ——. Report upon the examination of the outlets of sewers and the - effect of sewage disposal in Massachusetts: _Report Mass. State Board - of Health_, pp. 285–452, 1902. - -Bibliography 16: - - ——, and HAZEN, ALLEN. A report of the chemical work done at the - Lawrence Experiment Station: _Examinations by the State Board of - Health of water supplies of Mass. 1887–90_, pt. 2, Purification of - sewage and water, pp. 707–34, 1890. - -Bibliography 17: - - DUPRE, Dr. Some observations on the permanganate test in water - analysis: _Analyst_, Vol. 10, pp. 118–22, 1885. - -Bibliography 18: - - ELLMS, J. W. A study of the relative value of lacmoid, phenacetolin, - and erythrosine as indicators in the determination of the alkalinity - of water by Hehner’s method: _J. Am. Chem. Soc._, Vol. 21, pp. 359–69, - 1899. - -Bibliography 20: - - ——, and BENEKER, J. C. The estimation of carbonic acid in water: _J. - Am. Chem. Soc._, Vol. 23, pp. 405–31, 1901. - -Bibliography 21: - - FARNSTEINER, BUTTENBURG, and KORN, _Leitfaden für die chemische - Untersuchung von Abwasser_, Berlin, p. 20, 1902. - -Bibliography 22: - - FITZGERALD, and FOSS, _Report Boston Water Board_, p. 86, 1893. - -Bibliography 23: - - FORBES, F. B., and PRATT, G. H. The determination of carbonic acid in - drinking water: _J. Am. Chem. Soc._, Vol. 25, pp. 742–56, 1903. - -Bibliography 24: - - FOWLER, G. J. Sewage works analyses, pp. 21–37, John Wiley & Sons, New - York, 1902; - -Bibliography 24a: - - pp. 31–4; - -Bibliography 24b: - - pp. 58–60; - -Bibliography 24c: - - pp. 86–9; - -Bibliography 24d: - - pp. 89–95; - -Bibliography 24e: - - pp. 96–7; - -Bibliography 24f: - - pp. 98–100. - -Bibliography 26: - - FOWLER, G. J. _Univ. of Manchester Lecture_, March, 1904, Pamphlet, p. - 7. - -Bibliography 27: - - FOX, CHARLES J. J. On the coefficients of absorption of nitrogen and - oxygen in distilled water and sea water and of atmospheric carbonic - acid in sea water: _Trans. Faraday Soc._, Vol. 5, pp. 68–87, 1909. - -Bibliography 29: - - ——. The composition of sewage in relation to problems of disposal: - _Tech. Quart._, Vol. 16, pp. 132–160, 1903. - -Bibliography 30: - - ——. Experiments upon the purification of sewage and water at the - Lawrence Experiment Station: _Report Mass. State Board of Health_, pp. - 447–700, 1894. - -Bibliography 31: - - HAYWOOD, J. K., and WARNER, H. J. Arsenic in papers and fabrics: _U. - S. Agri. Dept. Bur. Chem. Bull. 86_, pp. 25–7, 1904. - -Bibliography 32: - - GILL, A. H. On the determination of nitrates in potable water: _J. Am. - Chem. Soc._, Vol. 16, pp. 122–32, 193–7, 1894. - -Bibliography 33: - - GOOCH, F. A. A method for the separation and estimation of boric acid: - _Am. Chem. J._, Vol. 9, pp. 23–33, 1887. - -Bibliography 34: - - ——. A method for the separation of sodium and potassium from lithium - by the action of amyl alcohol on the chlorides: _Am. Chem. J._, Vol. - 9, pp. 33–51, 1887; also _U. S. Geol. Survey Bull. 422_, p. 175; also - _U. S. Agri. Dept. Bur. Chem._, _Bull. 152_, p. 80, 1911. - -Bibliography 35: - - GOTTSCHALK, V. H., and ROESLER, H. A. Action of soap on calcium and - magnesium solutions: _J. Am. Chem. Soc._, Vol. 26, pp. 851–6, 1904. - -Bibliography 36: - - GRANDVAL, AL., and LAJOUX, H. Nouveau procédé pour la recherche et le - dosage rapide de faibles quantités d’ acide nitrique dans l’air, - l’eau, le sol, etc., _Comptes rend._, Vol. 101, pp. 62–5, 1885. - -Bibliography 37: - - HANDY, J. O. Determination of acidity or alkalinity: _Proc. Engineers - Soc. West. Pa._, Vol. 19, p. 705, 1903. - -Bibliography 38: - - HARRINGTON, CHARLES, and RICHARDSON, M. W. A manual of practical - hygiene, 5th ed., pp. 457–62, Lea & Febiger, Phila. and New York, - 1914. - -Bibliography 39: - - HAZEN, ALLEN. On the determination of chlorine in water: _Am. Chem. - J._, Vol. 11, pp. 409–14, 1889. - -Bibliography 40: - - ——. Apparatus for the determination of ammonias in sand sewage: _Am. - Chem. J._, Vol. 12, pp. 427–8, 1890. - -Bibliography 42: - - ——. Report on the chemical precipitation of sewage: _Examinations by - the State Board of Health of water supplies of Mass., 1887–90_, pt. 2, - Purification of water and sewage, pp. 735–91, 1890. - -Bibliography 43: - - ——. 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E. Water Works - Assoc._, Vol. 13, pp. 94–118, 1898. - -Bibliography 50: - - HOWE, FREELAND, JR. A new method for determining the color of the - turbidity of water: _Eng. Rec._, Vol. 50, pp. 720–1, 1904. - -Bibliography 51: - - ILOSVAY, L. L’acide azoteux dans la salive et dans l’air exhalé: - _Bull. de la Sociéte Chimique_, ser. 3, Vol. 2, pp. 388–91, 1889. - -Bibliography 52: - - JACKSON, D. D. Permanent standards for use in the analysis of water: - _Tech. Quart._, Vol. 13, pp. 314–26, 1900. - -Bibliography 52a: - - _a._ ——, and HORTON, W. A. Experiments on the putrescibility test for - sewage and sewage effluents: _J. Ind. Eng. Chem._, Vol. 1, pp. 328–33, - 1909. - -Bibliography 53: - - ——, and ELLMS, J. W. On odors and tastes of surface waters, with - special reference to anabaena, a microscopical organism found in - certain water supplies of Massachusetts: _Tech. Quart._, Vol. 10, pp. - 410–20, 1897. - -Bibliography 54: - - JOHNSON, G. A. Report on sewage purification at Columbus, Ohio, made - to the chief engineer of the Board of Public Service, p. 47, 1905. - -Bibliography 55: - - KENDALL, L. M., and RICHARDS, E. H. Permanent standards in water - analysis: _Tech. Quart._, Vol. 17, pp. 277–80, 1904. - -Bibliography 56: - - KIMBERLEY, A. E., and HOMMON, H. B. The practical advantages of the - Gooch crucible in the determination of the total and volatile - suspended matter in sewage: _Pub. Health Papers and Repts._, _Am. Pub. - Health Assoc._, Vol. 31, pt. 2, pp. 123–35, 1905. - -Bibliography 57: - - KINNICUTT, L. P. Quoted by Gage, _J. Am. Chem. Soc._, Vol. 27, p. 339, - 1905. - -Bibliography 58: - - KJELDAHL, J. Neue Methode zur Bestimmung des Stickstoffs in - organischen Körpern: _Z. anal. Chem._, Vol. 22, pp. 366–82, 1883. - -Bibliography 59: - - KLUT, _Mitt. a. d. König. Prüfungs_, Vol. 12, p. 186. - -Bibliography 60: - - LEACH, A. E. Food inspection and analysis, pp. 493, 495, and 497, John - Wiley & Sons, New York, 1904. - -Bibliography 60a: - - _a._ LEDERER, ARTHUR. A new method for determining the relative - stability of sewage, effluent, or polluted river water: _J. Infect. - Diseases_, Vol. 14, pp. 482–97, 1914. - -Bibliography 60b: - - _b._ ——. A serious fallacy of the “standard” methylene blue - putrescibility test: _Am. J. Pub. Health_, Vol. 4 (old series Vol. - 10), pp. 241–8, 1914. - -Bibliography 60c: - - _c._ ——. Notes on the practical application of the “saltpeter method” - for determining the strength of sewages: _Am. J. Pub. Health_, Vol. 5, - pp. 354–61, 1915. - -Bibliography 60d: - - _d._ ——. Determination of the biochemical oxygen demand by the - saltpeter method in stockyards, tannery, and corn products wastes: _J. - Ind. Eng. Chem._, Vol. 7, pp. 514–6, 1915. - -Bibliography 61: - - LEEDS, A. R. Estimation by titration of dissolved carbon dioxide in - water: _J. Am. Chem. Soc._, Vol. 13, pp. 98–9, 1891. - -Bibliography 62: - - ——. The alteration of standard ammonium solutions when kept in the - dark: _Proc. Am. Chem. Soc._, Vol. 2, p. 1, 1878. - -Bibliography 63: - - LEFFMAN, HENRY. Examination of water, 3d ed., pp. 46–50, P. - Blakiston’s Son & Co., Philadelphia, 1895; - -Bibliography 63a: - - pp. 44–6; - -Bibliography 63b: - - pp. 57–8. - -Bibliography 64: - - ——. Examination of water, 7th ed., pp. 35–7, P. Blakiston’s Son & Co., - Philadelphia, 1915; - -Bibliography 64a: - - pp. 64–7. - -Bibliography 65: - - LEVY, D. D. _Ann. de l’Observatoire de Mont-Souris_, 1883 _et seq._ - -Bibliography 66: - - LOVIBOND, J. W. A description of the tintometer with some remarks on - its application to chemical analysis: _J. Soc. Chem. Ind._, Vol. 7, - pp. 424–6, 1888. - -Bibliography 67: - - MALLET, J. W. Water analysis: _Annual Report National Board of - Health_, pp. 189–354, 1882. - -Bibliography 68: - - MASON, W. P. Examination of water, 4th ed., pp. 85–9, John Wiley & - Sons, New York, 1910; - -Bibliography 68a: - - pp. 33–41; - -Bibliography 68b: - - pp. 59–74; - -Bibliography 68c: - - pp. 106–9. - -Bibliography 69: - - MCGOWAN, GEORGE. Kjeldahl process for the estimation of total nitrogen - and (indirectly) of total organic nitrogen: _Royal Commission on - Sewage Disposal_, Vol. 4, pt. 5, pp. 24–31, 1904; - -Bibliography 69a: - - pp. 37–41; - -Bibliography 69b: - - pp. 47–8. - -Bibliography 70: - - PALMER, A. W. Chemical survey of the waters of Illinois, Report for - years 1897–1902, pp. 27–8, Univ. Ill., 1903. - -Bibliography 71: - - ——. Report of the University of Illinois [in Report of streams - examination, Sanitary Dist. Chicago], p. 60, Chicago, 1903; - -Bibliography 71a: - - p. 56; - -Bibliography 71b: - - pp. 61–4. - -Bibliography 72: - - PARKER, G. H. Report of the biologist: _Examinations by the State - Board of Health of water supplies of Mass., 1887–90_, pt. 1, - Examination of water supplies, pp. 583–7, 1890. - -Bibliography 73: - - PARMELEE, C. L., and ELLMS, J. W. On rapid methods for the estimation - of the weight of suspended matters in turbid waters: _Tech. Quart._, - Vol. 12, pp. 145–64, 1899. - -Bibliography 74: - - PFEIFER, J., and WARTHA, PROF. Kritische Studien über Untersuchung und - Reinigung des Kesselspeisewassers: _Z. angew. Chem._, Vol. 15, pp. - 193–207, 1902. - -Bibliography 75: - - PHELPS, E. B. A critical study of the methods in current use for the - determination of free and albuminoid ammonia in sewage, _Public Health - Papers and Reports, Am. Pub. Health Assoc._, Vol. 29, p. 354, 1904; J. - Infect. Dis., Vol. 1, p. 327, 1904. - -Bibliography 76: - - ——. The determination of the organic nitrogen in sewage by the - Kjeldahl process: _J. Infect. Dis._, Supp. 1, pp. 255–72, 1905. - -Bibliography 77: - - ——. The determination of small quantities of copper in water: _J. Am. - Chem. Soc._, Vol. 28, pp. 368–72, 1906. - -Bibliography 78: - - ——. Putrescibility and stability of sewage effluents: _Contrib. Sanit. - Research Lab., Mass. Inst. Tech._, Vol. 5, p. 87, 1909; also The - disinfection of sewage and sewage filter effluents: _U. S. Geol. - Survey Water-Supply Paper 229_, pp. 74–88, 1909. - -Bibliography 79: - - Preface to report of committee on the pollution of water supplies: - _Public Health Papers and Reports, Am. Pub. Health Assoc._, Vol. 23, - pp. 56–7, 1897. Report, pp. 58–100. - -Bibliography 80: - - Report of committee on standard methods of water analysis: _Public - Health Papers and Reports, Am. Pub. Health Assoc._, Vol. 27, pp. - 377–91, 1901. - -Bibliography 81: - - PROCTOR, H. R. Some recent methods of technical water analysis: _J. - Soc. Chem. Ind._, Vol. 23, pp. 8–11, 1904. - -Bibliography 82: - - ——. On a modified form of tintometer or colorimeter: _J. Soc. Chem. - Ind._, Vol. 14, pp. 122–4, 1895. - -Bibliography 83: - - RICHARDS, E. H., and ELLMS, J. W. The coloring matter of natural - waters, its source, composition, and quantitative measurement: _J. Am. - Chem. Soc._, Vol. 18, pp. 68–81, 1896. - -Bibliography 84: - - RIDEAL, SAMUEL. Sewage, 2d ed., pp. 38–40, John Wiley & Sons, New - York, 1901; - -Bibliography 84a: - - pp. 31–4. - -Bibliography 85: - - Royal Commission on Sewage Disposal, Testimony, Vol. 2, pp. 326–37, - 1902. - -Bibliography 86: - - SCHOLL, CLARENCE. The perchloric method of determining potassium as - applied to water analysis: _J. Am. Chem. Soc._, Vol. 36, pp. 2985–9, - 1914. - -Bibliography 87: - - SEYLER, C. A. Notes on water analysis: _Chem. News_, Vol. 70, pp. - 82–3, 104–5, 112–4, 140–1, 151–2, and 187, 1894. - -Bibliography 88: - - ——. The estimation of carbonic acid in natural waters: _Analyst_, Vol. - 22, pp. 312–9, 1897. - -Bibliography 89: - - SMART, CHAS. Report of the committee on pollution of water supplies: - _Public Health Papers and Reports, Am. Pub. Health Assoc._, Vol. 20, - pp. 72–82, 1895; - -Bibliography 89a: - - pp. 459–516. - -Bibliography 90: - - SPRENGEL, HERMANN. Ueber die Erkennung der Salpetersaüre: _Ann. Physik - und Chemie_, Vol. 121, pp. 188–91, 1864. - -Bibliography 91: - - Standard methods of water analysis: _Science_, new ser., Vol. 12, pp. - 906–15, 1900. - -Bibliography 92: - - STEARNS, F. P., and DROWN, T. M. Discussion of special topics relating - to the quality of public water supplies: _Examinations by the State - Board of Health of water supplies of Mass., 1887–90_, pt. 1, - Examination of water supplies, pp. 740–9, 1890. - -Bibliography 93: - - STREET, J. P. Report on nitrogen: [In _Proc. Assoc. Off. Agri. - Chemists_]; _U. S. Agri. Dept. Bur. Chem. Bull. 49_, pp. 12–25, 1897. - -Bibliography 94: - - SUTTON, FRANCIS. Volumetric analysis, 10th ed., pp. 72–4, P. - Blakiston’s Son & Co., Philadelphia, 1911; - -Bibliography 94a: - - pp. 99–101; - -Bibliography 94b: - - pp. 239 and 477; - -Bibliography 94c: - - pp. 470–1; - -Bibliography 94d: - - pp. 479–83; - -Bibliography 94e: - - p. 473, 479–83; - -Bibliography 94f: - - pp. 484–8. - -Bibliography 95: - - TATLOCK, R. R., and THOMPSON, R. T. The analysis of waters and their - changes in composition when employed in steam raising: _J. Soc. Chem. - Ind._, Vol. 23, pp. 428–31, 1904. - -Bibliography 96: - - THOMAS, G. E., and HALL, C. A. New apparatus in water analysis: _J. - Am. Chem. Soc._, Vol. 24, pp. 535–9, 1902. - -Bibliography 97: - - THOMSON, R. T. Use of litmus, methyl orange, phenacetolin, and - phenolphthalein as indicators: _Chem. News_, Vol. 47, pp. 123–7, 1883. - -Bibliography 98: - - THOMSON, ANDREW. Colorimetric method for determining small quantities - of iron: _J. Chem. Soc._, Vol. 47, pp. 493–7, 1885. - -Bibliography 99: - - THRESH, J. C. A new method of estimating the oxygen dissolved in - water: _J. Chem. Soc._, Vol. 57, pp. 185–95, 1890. - -Bibliography 100: - - ——. The examination of water and water supplies, p. 200, Philadelphia, - 1904; - -Bibliography 100a: - - p. 219; - -Bibliography 100b: - - p. 195; - -Bibliography 100c: - - p. 282. - -Bibliography 101: - - TIDY, C. M. The process for determining the organic purity of potable - waters: _J. Chem. Soc._, Vol. 35, pp. 46–106, 1879. - -Bibliography 102: - - TIEMANN, FERDINAND, and GÄRTNER, AUGUST. Handbuch der Wässer, 4th ed., - pp. 255–8, Friedrich Vieweg und Sohn, Braunschweig, 1895. - -Bibliography 103: - - TREADWELL, F. P. [translated by Hall, W. T.], Analytical Chemistry, 3d - ed., Vol. 2, pp. 687–688, John Wiley & Sons, New York, 1911; - -Bibliography 103a: - - pp. 50–3. - -Bibliography 104: - - TROMMSDORFF, HUGO. Bestimmung der Organischen Substanzen: _Zeit. Anal. - Chem._, Vol. 8, p. 344, 1869. - -Bibliography 105: - - U. S. GEOLOGICAL SURVEY. Measurement of color and turbidity of water, - Form 9–182, Washington, 1902. - -Bibliography 106: - - WANKLYN, J. A. Verification of Wanklyn, Chapman, and Smith’s water - analyses on a series of artificial waters: _J. Chem. Soc._, Vol. 20, - pp. 591–5, 1867. - -Bibliography 107: - - ——. Water analysis, 10th ed., pp. 33–5, Kegan, Paul, Trench, Trübner, - & Co., Ltd., London, 1896; - -Bibliography 107a: - - pp. 106–7. - -Bibliography 108: - - WARINGTON, ROBERT. Note on the appearance of nitrous acid during - evaporation of water: _J. Chem. Soc._, Vol. 39, pp. 229–34, 1881. - -Bibliography 109: - - WARREN, H. E., and WHIPPLE, G. C. The thermophone, a new instrument - for determining temperatures: _Tech. Quart._, Vol. 8, pp. 125–52, - 1895. - -Bibliography 110: - - WEST, F. D. The preparation of standards for the determination of - turbidity of water: _Proc. Ill. Water Supply Assoc._, Vol. 6, pp. - 49–51, 1914. - -Bibliography 111: - - WESTON, R. S. Apparatus for the determination of ammonia in water by - the Wanklyn method, and total nitrogen by the Kjeldahl method: _J. Am. - Chem. Soc._, Vol. 22, pp. 468–73, 1900. - -Bibliography 112: - - ——. The determination of nitrogen as nitrites in waters: _J. Am. Chem. - Soc._, Vol. 27, pp. 281–7, 1905. - -Bibliography 113: - - ——. The determination of manganese in water: _J. Am. Chem. Soc._, Vol. - 29, pp. 1074–8, 1907. - -Bibliography 114: - - WHIPPLE, G. C. The observation of odor as an essential part of water - analysis: _Public Health Papers and Reports, Am. Pub. Health Assoc._, - Vol. 25, pp. 587–93, 1899. - -Bibliography 115: - - ——. The microscopy of drinking water, 3d ed., pp. 186–205, John Wiley - & Sons, New York, 1914. - -Bibliography 116: - - ——, and JACKSON, D. D. A comparative study of the methods used for the - measurement of the turbidity of water: _Tech. Quart._, Vol. 13, pp. - 274–94, 1900. - -Bibliography 117: - - ——, and others. The decolorization of water: _Trans. Am. Soc. Civil - Eng._, Vol. 46, pp. 141–81, 1901. - -Bibliography 118: - - ——, and PARKER, H. N. On the amount of oxygen and carbonic acid - dissolved in natural waters and the effect of these gases upon the - occurrence of microscopic organisms: _Trans. Am. Microscopical Soc._, - Vol. 23, pp. 103–44, 1901. - -Bibliography 119: - - ——, and WHIPPLE, M. C. Solubility of oxygen in sea water: _J. Am. - Chem. Soc._, Vol. 33, pp. 362–5, 1911. - -Bibliography 120: - - WINKLER, L. W. Die Bestimmung des im Wasser gelösten Sauerstoffes: - _Ber._, pp. 2843–54, 1888. - -Bibliography 121: - - WOODMAN, A. G., and NORTON, J. F. Air, water, and food, 4th ed., pp. - 72–8, John Wiley & Sons, New York, 1914; - -Bibliography 121a: - - pp. 85–7; - -Bibliography 121b: - - pp. 90–1, 216, and 231; - -Bibliography 121c: - - pp. 106–8. - - - - - MICROSCOPICAL EXAMINATION. - - -The microscopical examination of water consists of the enumeration of -the kinds of microscopic organisms (Plankton), and an estimation of -their quantity. - -It may serve any one or more of the following purposes: - - (1) To explain the presence of objectionable odors and tastes. - - (2) To indicate the progress of the self purification of streams. - - (3) To indicate the presence of sewage contamination. - - (4) To explain the chemical analysis. - - (5) To identify the source of a water. - - (6) To aid in the study of the food of fish, shellfish, and other - aquatic organisms. - -The term “Microscopic Organisms” shall include all organisms microscopic -or barely visible to the naked eye, with the exception of the bacteria. -It includes the diatomaceae, chlorophyceae, cyanophyceae, fungi, -protozoa, rotifera, crustacea, bryophyta, and spongidae found in water. - -Fragments of organic matter, silt, mineral matter, zoöglea, etc., shall -be considered as amorphous matter. The recording of amorphous matter -usually serves no useful purpose and shall not be considered a part of -the standard method. - -_Apparatus._—1. A cylindrical funnel about two inches in diameter at the -top, with a straight side for nine inches, narrowed over a distance of -three inches to a bore of one-half inch in diameter, and terminating in -a straight portion of this diameter two and one-half inches in length. -The capacity of this funnel is 500 cc. It shall be provided at the -bottom with a tightly fitting rubber stopper with a single perforation -and a disk of silk bolting cloth over the hole about three eighths of an -inch in diameter. - -2. A counting cell consisting of a brass rim closely cemented to a plate -of optical glass. The shape and size of this cell are not essential but -its depth shall be one millimeter. A convenient capacity is about one -cubic centimeter. - -3. An ocular micrometer ruled as follows: The ocular micrometer is -commonly of such a size that with a 16 mm. objective and a suitable tube -length, the largest square cuts off one square millimeter on the stage. - -_Procedure._—Filter 250 cc. of the water (more or less according to the -clearness of the sample) through a one-half inch layer of quartz sand -(washed and screened between 60 and 120 mesh sieves) supported by the -disk of bolting cloth and rubber stopper at the bottom of the funnel. -Suction may be applied to hasten the filtration. - -Remove the stopper and catch the plug of sand and its entrained -organisms in a small beaker or test tube, washing down the inside of the -funnel into the beaker with 5 cc. of clean (preferably distilled) water. -Agitate the mixture of sand, water, and organisms to detach the latter -from the sand grains, and quickly decant the water and the organisms in -suspension to a test tube. If desired the sand may then be again washed -with 5 cc. water and the wash water added to the first portion. - -Cover the cell partially with a cover glass, and by means of a pipette -run the concentrate under the cover glass until the cell is completely -filled. - -Cover and place on the microscope stage in a horizontal position for -examination. - -Count the organisms in twenty fields, i. e., twenty cubic millimeters, -estimating their areas in terms of Standard Units. - -_The Standard Unit is the smallest square in the ocular micrometer, and -represents an area 20µ × 20µ, or 400 square microns on the stage._ - -Results shall be expressed in the number of Standard Units of each kind -of micro-organism per cc. and also the total number of standard units of -all kinds per cc. The general directions as to significant figures given -under Turbidity shall apply also to the microscopical examination. - -_Caution._—Many micro-organisms, especially some of those causing odors, -are so fragile that they are broken up in filtration, especially if the -agitation of the filtrate is too vigorous. A direct examination of a -fresh sample is therefore a useful supplementary procedure. For the same -reason the concentrate should not stand long before examination. Also -some organisms are carried by specific gravity to the top of the cell -which should be scrutinized as well as the bottom layer each time. - -It is always better to examine the micro-organisms in the field when -possible, and for this purpose the sling filter has been devised -consisting of a metal funnel slung to a pivoted handle, with a disk of -wire gauze in the detachable lower end to support the sand. Filtration -is hastened by imparting a whirling motion to the whole and utilizing -the centrifugal force thus generated. - -[Illustration: THE OCULAR MICROMETER.] - - - MICROSCOPICAL BIBLIOGRAPHY. - - _a._ KEAN, A. L. A new method for the microscopical examination of - water: _Science_, Vol. 13, p. 132, 1889; _Eng. News_, pp. 21, - 276, 1889. - - _b._ SEDGWICK, W. T. Recent progress in biological water analysis: _J. - N. E. Water Works Assoc._, Vol. 4, pp. 50–64, 1889. - - _c._ ——. A report of the biological work of the Lawrence Experiment - Station: _Examinations by the State Board of Health of water - supplies of Mass., 1887–90_, pt. 2, Purification of sewage and - water, pp. 793–862, 1890. - - _d._ PARKER, G. H. Report upon the organisms, excepting the bacteria - found in the waters of the State: _Examinations by the State - Board of Health of water supplies of Mass., 1887–90_, pt. 1, - Examination of water supplies, pp. 579–620, 1890. - - _e._ RAFTER, G. W. The microscopical examination of potable water, D. - Van Nostrand Co., New York, 1910. (Contains bibliography.) - - _f._ CALKINS, G. N. The microscopical examination of water: _Report - Mass. State Board of Health_, pp. 397–421, 1892. - - _g._ JACKSON, D. D. On an improvement in the Sedgwick-Rafter method for - the microscopical examination of drinking water: _Tech. Quart._, - Vol. 9, pp. 271–4, 1896. - - _h._ WHIPPLE, G. C. Experience with the Sedgwick-Rafter method at the - Biological Laboratory of the Boston Water Works: _Tech. Quart._, - Vol. 9, pp. 275–9, 1896. - - _i._ ——. Microscopy of drinking water, 3d ed., John Wiley & Sons, New - York, 1914. (Contains bibliography.) - - - - - BACTERIOLOGICAL EXAMINATION. - - - I. APPARATUS. - -1. _Sample Bottles._—Any size, shape or quality of bottle may be used -for a bacterial sample, provided it holds a sufficient amount to carry -out all the tests required and is such that it may be properly washed -and sterilized and will keep the sample uncontaminated until the -analysis is made. Four- or eight-ounce, ground-glass-stoppered bottles -are recommended. These should be protected by being wrapped in paper, or -their necks covered with tin foil, and should be placed in proper boxes -for transportation. - -2. _Pipettes._—Pipettes may be of any convenient size or shape provided -it is found by actual test that they deliver accurately the required -amount in the manner in which they are used. The error of calibration -shall in no case exceed 2 per cent. Protecting the pipettes with a -cotton stopper is recommended. - -3. _Dilution Bottles._—Bottles for use in making dilutions should -preferably be of tall form, of such capacity as to hold at least twice -the volume of water actually used. Close-fitting ground-glass stoppers -are preferable, but tight fitting cotton stoppers may be used, provided -due care is taken to prevent contamination and to avoid loss of volume -through wetting of the stopper before mixing has been accomplished. - -4. _Petri Dishes._—Petri dishes ten centimeters in diameter shall be -used with glass or porous tops[211] as preferred. The bottoms of the -dishes shall be as flat as possible so that the medium shall be of -uniform thickness throughout the plate. - -5. _Fermentation Tubes._—Any type of fermentation tube[203] may be used -provided it holds at least three times as much medium as the amount of -water to be tested. - - - II. MATERIALS. - -1. _Water._—Distilled water shall be used in the preparation of all -culture media and reagents. - -2. _Meat Extract._—Liebig’s meat extract shall be used in place of meat -infusion. Other brands may be substituted for Liebig’s when comparative -tests have shown that they give equivalent results. - -3. _Peptone._—Armour’s, Digestive Ferments Company’s, Fairchild’s, or -any other peptone which gives equivalent results may be used. - -4. _Sugars._—All sugars used shall be of the highest purity obtainable. - -5. _Agar._—The agar used shall be of the best quality and shall be dried -for one-half hour at 105° C. before weighing. Much of the agar on the -market contains considerable amounts of sea salts.[221][225][228] These -may be removed by soaking in water and draining before use. - -6. _Gelatin._—The gelatin used shall be of light color, shall contain -not more than a trace of arsenic, copper, sulfides, and shall be free -from preservatives, and of such a melting point that a 10 per cent. -standard nutrient gelatin shall have a melting point of 25° C. or over. -Gelatin shall be dried for one-half hour at 105° C. before weighing. - -7. _Litmus._—Reagent litmus of highest purity (not litmus cubes) or -azolitmin (Kahlbaum) shall be used for all media requiring a litmus -indicator. - -8. _General Chemicals._—Special effort shall be made to have all the -other ingredients used for culture media chemically pure. - - - III. METHODS. - - - 1. PREPARATION OF CULTURE MEDIA. - - - a. _Adjustment of Reaction._ - -_aa._ _Phenol Red Method for adjustment to a hydrogen-ion concentration -of P_{H+} = 6.8–8.4._ Withdraw 5 cc. of the medium, dilute with 5 cc. of -distilled water, and add 5 drops of a solution of phenol red (phenol -sulphone phthalein). This solution is made by dissolving 0.04 grams of -phenol red in 30 cc. of alcohol and diluting to 100 cc. with distilled -water. - -Titrate with a 1:10 dilution of a standard solution of NaOH (which need -not be of known normality) until the phenol red shows a slight but -distinct pink color. Calculate the amount of the standard NaOH solution -which must be added to the medium to reach this reaction. After the -addition check the reaction by adding 5 drops of phenol red to 5 cc. of -the medium and 5 cc. of water. - -_bb._ _Titration with phenolphthalein._ (For the convenience of those -who wish to retain the use of this method for the present it is given -here, but it is recommended that as soon as possible the more accurate -method of determining the hydrogen-ion concentration be substituted.) - -In a white porcelain dish put 5 cc. of the medium to be tested, add 45 -cc. of distilled water. Boil briskly for one minute. Add 1 cc. of -phenolphthalein solution (5 grams of commercial salt to one liter of 50 -per cent. alcohol). Titrate immediately with a n/20 solution of sodium -hydrate. A faint but distinct pink color marks the true end-point. This -color may be precisely described as a combination of 25 per cent. of red -(wave length approximately 658) with 75 per cent. of white as shown by -the disks of the standard color top made by the Milton Bradley -Educational Co., Springfield, Mass. - -All reactions shall be expressed with reference to the phenolphthalein -neutral point and shall be stated in percentages of normal acid or -alkali solutions required to neutralize them. Alkaline media shall be -recorded with a minus (-) sign before the percentage of normal acid -needed for their neutralization and acid media with a plus (+) sign -before the percentage of normal alkali solution needed for their -neutralization. - -The standard reaction for culture media for water analysis shall be +1.0 -per cent., as determined by tests of the sterilized medium. As -ordinarily prepared, broth and agar will be found to have a reaction -between +0.5 and +1.0. For such media no adjustment shall be made. The -reaction of media containing sugar shall be neutral to phenolphthalein. -Whenever reactions other than the standard are used, it shall be so -stated. - - - b. _Sterilization._ - -All media and dilution water shall be sterilized in the autoclav at 15 -lbs. (120° C.) for 15 minutes after the pressure reaches 15 lbs. All air -must be forced out of the autoclav before the pressure is allowed to -rise. As soon as possible after sterilization the media shall be removed -from the autoclav and cooled rapidly. Rapid and immediate cooling of -gelatin is imperative. - -Media shall be sterilized in small containers, and these must not be -closely packed together. No part of the medium shall be more than 2.5 -cm. from the outside surface of the glass. All glassware shall be -sterilized in the dry oven at 170° C. for at least 1½ hours. - - - c. _Nutrient Broth. To Make One Liter._ - -1. Add 3 grams of beef extract and 5 grams of peptone to 1,000 cc. of -distilled water. - -2. Heat slowly on a steam bath to at least 65° C. - -3. Make up lost weight and adjust the reaction to a faint pink with -phenol red, or if the phenolphthalein titration is used, and the -reaction is not already between +0.5 and +1, adjust to +1. - -4. Cool to 25° C. and filter through filter paper until clear. - -5. Distribute in test-tubes, 10 cc. to each tube. - -6. Sterilize in the autoclav at 15 lbs. (120° C.) for 15 minutes after -the pressure reaches 15 lbs. - - - d. _Sugar Broths._ - -Sugar broths shall be prepared in the same general manner as nutrient -broth with the addition of 0.5 per cent. of the required carbohydrate -just before sterilization. The removal of muscle sugar is unnecessary as -the beef extract and peptone are free from any fermentable -carbohydrates. The reaction of sugar broths shall be a faint pink with -phenol red or, if on titration with phenolphthalein the reaction is not -already between neutral and +1, adjust to neutral. Sterilization shall -be in the autoclav at 15 lbs. (120° C.) for 15 minutes after the -pressure reaches 15 lbs., provided the total time of exposure to heat is -not more than one-half hour; otherwise a 10 per cent. solution of the -required carbohydrate shall be made in distilled water and sterilized at -100° C. for 1½ hours, and this solution shall be added to sterile -nutrient broth in amounts sufficient to make a 0.5 per cent. solution of -the carbohydrate and the mixture shall then be tubed and sterilized at -100° C. for 30 minutes, or it is permissible to add by means of a -sterile pipette directly to a tube of sterile neutral broth enough of -the carbohydrate to make the required 0.5 per cent. The tubes so made -shall be incubated at 37° C. for 24 hours as a test for sterility. - - - e. _Nutrient Gelatin. To Make One Liter._ - -1. Add 3 grams of beef extract and 5 grams of peptone to 1,000 cc. of -distilled water and add 100 grams of gelatin dried for one-half hour at -105° C. before weighing. - -2. Heat slowly on a steam bath to 65° C. until all gelatin is -dissolved.[G] - -Footnote G: - - The solution of the gelatin will be facilitated by allowing it to soak - in the cold one-half hour before heating. - -3. Make up lost weight and adjust the reaction to a faint pink with -phenol red, or if the phenolphthalein titration is used, and the -reaction is not already between +0.5 and +1, adjust to +1. - -4. Filter through cloth and cotton until clear. - -5. Distribute in test-tubes, 10 cc. to each tube, or in larger -containers as desired. - -6. Sterilize in the autoclav at 15 lbs. (120° C.) for 15 minutes after -the pressure reaches 15 lbs. - - - f. _Nutrient Agar. To Make One Liter._ - -1. Add 3 grams of beef extract, 5 grams of peptone and 12 grams of agar, -dried for one-half hour at 105° C. before weighing, to 1,000 cc. of -distilled water. Boil over a water bath until all agar is dissolved, and -then make up the loss by evaporation. - -2. Cool to 45° C. in a cold water bath, then warm to 65° C. in the same -bath, without stirring. - -3. Make up lost weight and adjust the reaction to a faint pink with -phenol red, or if the phenolphthalein titration is used, and the -reaction is not already between +0.5 and +1, adjust to +1. - -4. Filter through cloth and cotton until clear. - -5. Distribute in test-tubes, 10 cc. to each tube, or in larger -containers, as desired. - -6. Sterilize in the autoclav at 15 lbs. (120° C.) for 15 minutes after -the pressure reaches 15 lbs. - - - g. _Litmus or Azolitmin Solution._ - -The standard litmus solution shall be a 2 per cent. aqueous solution of -reagent litmus. Powder the litmus, add to the water and boil for five -minutes. The solution usually needs no correction in reaction and may be -at once distributed in flasks or test-tubes and sterilized as is culture -media. It should give a distinctly blue plate when 1 cc. is added to 10 -cc. of neutral culture medium in a Petri dish. - -The standard azolitmin solution shall be a 1 per cent. solution of -Kahlbaum’s azolitmin. Add the azolitmin powder to the water and boil for -five minutes. The solution may need to be corrected in reaction by the -addition of sodium hydrate solution so that it will be approximately -neutral and will give a distinctly blue plate when 1 cc. is added to 10 -cc. of neutral culture medium in a Petri dish. It may be distributed in -flasks or test-tubes and sterilized as is culture media. - - - h. _Litmus-lactose-agar._ - -Litmus-lactose-agar shall be prepared in the same manner as nutrient -agar with the addition of 1 per cent. of lactose just before -sterilization. The reaction shall be a faint pink with phenol red, or, -if on titration with phenolphthalein the reaction is not already between -neutral and +1, adjust to neutral. One cc. of sterilized litmus or -azolitmin solution shall be added to each 10 cc. of the medium just -before it is poured into the Petri dish, or the mixture may be made in -the dish itself. - - - i. _Endo’s Medium._[209][214][215] _To Make One Liter._ - -1. Add 5 grams of beef extract, 10 grams of peptone and 30 grams of agar -dried for one-half hour at 105° C. before weighing, to 1,000 cc. of -distilled water. Boil on a water bath until all the agar is dissolved -and then make up the loss by evaporation. - -2. Cool the mixture to 45° C. in a cold water bath, then warm to 65° C. -in the same bath without stirring. - -3. Make up lost weight, titrate, and if the reaction is not already -between neutral and +1 adjust to neutral. - -4. Filter through cloth and cotton until clear. - -5. Distribute 100 cc. or larger known quantities in flasks large enough -to hold the other ingredients which are to be added later. - -6. Sterilize in the autoclav at 15 lbs. (120° C.) for 15 minutes after -the pressure reaches 15 lbs. - -7. Prepare a 10 per cent. solution of basic fuchsin in 95 per cent. -alcohol, allow to stand 20 hours, decant and filter the supernatant -fluid. This is a stock solution. - -8. When ready to make plates melt 100 cc. of agar in streaming steam or -on a water bath. Dissolve 1 gram of lactose in 15 cc. of distilled -water, using heat if necessary. Dissolve 0.25 gram anhydrous sodium -sulphite in 10 cc. water. To the sulphite solution add 0.5 cc. of the -fuchsin stock solution. Add the fuchsin-sulphite solution to the lactose -solution and then add the resulting solution to the melted agar. The -lactose used must be chemically pure and the sulphite solution must be -made up fresh. - -9. Pour plates and allow to harden thoroughly in the incubator before -use. - - - 2. COLLECTION OF SAMPLE. - -Samples for bacterial analysis shall be collected in bottles which have -been cleansed with great care, rinsed in clean water, and sterilized -with dry heat for at least one hour and a half at 170° C., or in the -autoclav at 15 lbs. (120° C.) for 15 minutes or longer after the -pressure reaches 15 lbs. - -Great care must be exercised to have the samples representative of the -water to be tested and to see that no contamination occurs at the time -of filling the sample bottles. - - - 3. STORAGE AND TRANSPORTATION OF SAMPLES. - -Because of the rapid and often extensive changes which may take place in -the bacterial flora of bottled samples when stored even at temperatures -as low as 10° C., it is urged, as of importance, that all samples be -examined as promptly as possible after collection. - -The time allowed for storage or transportation of a bacterial sample -between the filling of the sample bottle and the beginning of the -analysis should be not more than six hours for impure waters and not -more than twelve hours for relatively pure waters. During the period of -storage, the temperature shall be kept as near 10° C. as possible. Any -deviation from the above limits shall be so stated in making reports. - - - 4. DILUTIONS. - -Dilution bottles shall be filled with the proper amount of tap water so -that after sterilization they shall contain exactly 9 cc. or 99 cc. as -desired. The exact amount of water can only be determined by experiment -with the particular autoclav in use. If desired, the 9 cc. dilution may -be measured out from a flask of sterile water with a sterile pipette. - -Dilution bottles shall be sterilized in the autoclav at 15 lbs. (120° -C.) for 15 minutes after the pressure reaches 15 lbs. - -The sample bottle shall be shaken vigorously 25 times and 1 cc. -withdrawn and added to the proper dilution bottles as required. Each -dilution bottle after the addition of the 1 cc. of the sample, shall be -shaken vigorously 25 times before a second dilution is made from it or -before a sample is removed for plating. - - - 5. PLATING. - -All sample and dilution bottles shall be shaken vigorously 25 times -before samples are removed for plating. Plating shall be done -immediately after the dilutions are made. One cc. of the sample or -dilution shall be used for plating and shall be placed in the Petri -dish, first. Ten cc. of liquefied medium at a temperature of 40° C. -shall be added to the 1 cc. of water in the Petri dish. The cover of the -Petri dish shall be lifted just enough for the introduction of the -pipette or culture medium, and the lips of all test-tubes or flasks used -for pouring the medium shall be flamed. In making litmus-lactose-agar -plates, 1 cc. of sterile litmus or azolitmin solution shall be added to -each 10 cc. of culture medium either in the Petri dish or before pouring -into the Petri dish. The medium and sample in the Petri dish shall be -thoroughly mixed and uniformly spread over the bottom of the Petri dish -by tilting or rotating the dish. All plates shall be solidified as -rapidly as possible after pouring and gelatin plates shall be placed -immediately in the 20° C. incubator and the agar plates in the 37° C. -incubator. Endo plates shall be made by placing one loopful of the -material to be tested on the surface of the plate and distributing the -material with a sterile loop or glass rod. - - - 6. INCUBATION. - -All gelatin plates shall be incubated for 48 hours at 20 C. in a dark, -well-ventilated incubator in an atmosphere practically saturated with -moisture.[227] - -All agar plates shall be incubated for 24 hours at 37° C. in a dark, -well-ventilated incubator in an atmosphere practically saturated with -moisture. Glass covered plates shall be inverted in the incubator. Any -deviation from the above described method shall be stated in making -reports. - - - 7. COUNTING. - -In preparing plates, such amounts of the water under examination shall -be planted as will give from 25 to 250 colonies on a plate;[202] and the -aim should be always to have at least two plates giving colonies between -these limits. Where it is possible to obtain plates showing colonies -within these limits, only such plates should be considered in recording -results, except where the same amount of water has been planted in two -or more plates, of which one gives colonies within these limits, while -the others give less than 25 or more than 250. In such case, the result -recorded should be the average of all the plates planted with this -amount of water. Ordinarily it is not desirable to plant more than 1 cc. -of water in a plate; therefore, when the total number of colonies -developing from 1 cc. is less than 25, it is obviously necessary to -record the results as observed, disregarding the general rule given -above. - -Counting shall in all cases be done with a lens of 2½ diameter’s -magnification, 3½X. The Engraver’s Lens No. 146 made by the Bausch & -Lomb Optical Company fills the requirements, and is a convenient lens -for the purpose. - - - 8. THE TEST FOR THE PRESENCE OF MEMBERS OF THE B. COLI GROUP. - -It is recommended that the B. coli group be considered as including all -non-spore-forming bacilli which ferment lactose with gas formation and -grow aërobically on standard solid media. - -The formation of 10 per cent. or more of gas in a standard lactose broth -fermentation tube within 24 hours at 37° C. is presumptive evidence of -the presence of members of the B. coli group, since the majority of the -bacteria which give such a reaction belong to this group. - -The appearance of aërobic lactose-splitting colonies on -lactose-litmus-agar or Endo’s medium plates made from a lactose broth -fermentation tube in which gas has formed confirms to a considerable -extent the presumption that gas-formation in the fermentation tube was -due to the presence of members of the B. coli group. - -To complete the demonstration of the presence of B. coli as above -defined, it is necessary to show that one or more of these aërobic plate -colonies consists of non-spore-forming bacilli which, when inoculated -into a lactose broth fermentation tube, form gas. - -It is recommended that the standard tests for the B. coli group be -either (A) the _Presumptive_, (B) the _Partially Confirmed_, or (C) the -_Completed_ test as hereafter defined, each test being applicable under -the circumstances specified. - - - A. PRESUMPTIVE TEST. - -1. Inoculate a series of fermentation tubes with appropriate graduated -quantities of the water to be tested. In every fermentation tube there -must always be at least three times as much medium as the amount of -water to be tested. When necessary to examine larger amounts than 10 cc. -as many tubes as necessary shall be inoculated with 10 cc. each. - -2. Incubate these tubes at 37° C. for 48 hours. Examine each tube at 24 -and 48 hours, and record gas-formation. The records should be such as to -distinguish between: - -(a) Absence of gas-formation. - -(b) Formation of gas occupying less than ten per cent. (10%) of the -closed arm. - -(c) Formation of gas occupying more than ten per cent. (10%) of the -closed arm. - -More detailed records of the amount of gas formed, though desirable for -purposes of study, are not necessary for carrying out the standard tests -prescribed. - -3. The formation within 24 hours of gas occupying more than ten per -cent. (10%) of the closed arm of fermentation tube constitutes _a -positive presumptive test_. - -4. If no gas is formed in 24 hours, or if the gas formed is less than -ten per cent. (10%), the incubation shall be continued to 48 hours. The -presence of gas in any amount in such a tube at 48 hours constitutes _a -doubtful test_, which in all cases requires confirmation. - -5. The absence of gas formation after 48 hours’ incubation constitutes -_a negative test_. (An arbitrary limit of 48 hours’ observation -doubtless excludes from consideration occasional members of the B. coli -group which form gas very slowly, but for the purposes of a standard -test the exclusion of these occasional slow gas-forming organisms is -considered immaterial.) - - - B. PARTIALLY CONFIRMED TEST. - -1. Make one or more Endo’s medium or lactose-litmus-agar plates from the -tube which, after 48 hours’ incubation, shows gas formation from the -smallest amount of water tested. (For example, if the water has been -tested in amounts of 10 cc., 1 cc., and 0.1 cc., and gas is formed in 10 -cc., and 1 cc., not in 0.1 cc., the test need be confirmed only in the 1 -cc. amount.) - -2. Incubate the plates at 37° C., 18 to 24 hours. - -3. If typical colon-like red colonies have developed upon the plate -within this period, the confirmed test may be considered positive. - -4. If, however, no typical colonies have developed within 24 hours, the -test cannot yet be considered definitely negative, since it not -infrequently happens that members of the B. coli group fail to form -typical colonies on Endo’s medium or lactose-litmus-agar plates, or that -the colonies develop slowly. In such case, it is always necessary to -complete the test as directed under “C” 2 and 3. - - - C. COMPLETED TEST. - -1. From the Endo’s medium or lactose-litmus-agar plate made as -prescribed under “B,” fish at least two typical colonies, transferring -each to an agar slant and a lactose broth fermentation tube. - -2. If no typical colonies appear upon the plate within 24 hours, the -plate should be reincubated another 24 hours, after which at least two -of the colonies considered to be most likely B. coli, whether typical or -not, shall be transferred to agar slants and lactose broth fermentation -tubes. - -3. The lactose broth fermentation tubes thus inoculated shall be -incubated until gas formation is noted; the incubation not to exceed 48 -hours. The agar slants shall be incubated at 37° C. for 48 hours, when a -microscopic examination shall be made of at least one culture, selecting -one which corresponds to one of the lactose broth fermentation tubes -which has shown gas-formation. - -The formation of gas in lactose broth and the demonstration of -non-spore-forming bacilli in the agar culture shall be considered a -satisfactory completed test, demonstrating the presence of a member of -the B. coli group. - -The absence of gas-formation in lactose broth or failure to demonstrate -non-spore-forming bacilli in a gas-forming culture constitutes a -negative test. - - - APPLICATION OF PRESUMPTIVE, PARTIALLY CONFIRMED, AND COMPLETED TESTS. - - - A. The Presumptive Test. - - 1. When definitely positive, that is showing more than 10 per cent. - (10%) of gas in 24 hours, is sufficient: - - (a) As applied to all except the smallest gas-forming portion of - each sample in all examinations. - - (b) As applied to the smallest gas-forming portion in the - examination of sewage or of water showing relatively high - pollution, such that its fitness for use as drinking water does - not come into consideration. This applies to the routine - examinations of raw water in connection with control of the - operation of purification plants. - - 2. When definitely negative, that is showing no gas in 48 hours, is - final and therefore sufficient in all cases. - - 3. When doubtful, that is showing gas less than 10 per cent. (10%) (or - none) in 24 hours, with gas either more or less than 10 per cent. in - 48 hours, must always be confirmed. - - - B. The Partially Confirmed Test. - - 1. When definitely positive, that is, showing typical plate colonies - within 24 hours, is sufficient: - - (a) When applied to confirm a doubtful presumptive test in cases - where the latter, if definitely positive, would have been - sufficient. - - (b) In the routine examination of water supplies where a - sufficient number of prior examinations have established a - satisfactory index of the accuracy and significance of this test - in terms of the completed test. - - 2. When doubtful, that is, showing colonies of doubtful or negative - appearance in 24 hours, must always be completed. - - - C. The Completed Test. - - The completed test is required as applied to the smallest gas-forming - portion of each sample in all cases other than those noted as - exceptions under the “presumptive” and the “partially confirmed” - tests. - - The completed test is required in _all_ cases where the result of the - confirmed test has been doubtful. - - - 9. EXPRESSION OF RESULTS. - -In order to avoid fictitious accuracy and yet to express the numerical -results by a method consistent with the precision of the work, the -numbers of colonies of bacteria per cubic centimeter shall be recorded -as follows:[212] - - Number of bacteria per cc. - From 1 to 50 shall be recorded as found - " 51 " 100 " " " to the nearest 5 - " 101 " 250 " " " " " " 10 - " 251 " 500 " " " " " " 25 - " 501 " 1,000 " " " " " " 50 - " 1,001 " 10,000 " " " " " " 100 - " 10,001 " 50,000 " " " " " " 500 - " 50,001 " 100,000 " " " " " " 1,000 - " 100,001 " 500,000 " " " " " " 10,000 - " 500,001 " 1,000,000 " " " " " " 50,000 - " 1,000,001 " 10,000,000 " " " " " " 100,000 - -This applies to the gelatin count at 20° C. and to the agar count at 37° -C. - - -SUMMARY OF STEPS INVOLVED IN MAKING PRESUMPTIVE, PARTIALLY CONFIRMED AND - COMPLETED TESTS FOR B. COLI. - - ────────────────────────────────────────────────────────────┬───────── - Steps in procedure. │ Further - │procedure - │required. - ────────────────────────────────────────────────────────────┼───────── - I. Inoculate lactose broth fermentation tubes; incubate 24 │ - hours at 37° C.; observe gas-formation in each tube. │ - 1. Gas-formation, 10 per cent. or more; constitutes │ - positive presumptive test. │ - (a) For other than smallest portion of any sample │ - showing gas at this time, and for all portions, │ - including smallest, of sewage and raw water this│ - test is sufficient. │None - (b) For smallest gas-forming portion, except in │ - examinations of sewage and raw water. │III - 2. Gas-formation less than 10 per cent. in 24 hours; │ - inconclusive. │II - II. Incubate an additional 24 hours, making a total of 48 │ - hours’ incubation; observe gas-formation. │ - 1. Gas-formation, any amount; constitutes doubtful │ - test, which must always be carried further. │III - 2. No gas-formation in 48 hours; constitutes final │ - negative test. │None - III. Make plate from smallest gas-forming portion of sample │ - under examination; incubate 18 to 24 hours; observe │ - colonies. │ - 1. One or more colonies typical in appearance. │ - (a) If only “partially confirmed” test is required│None - (b) If completed test is required, select two │ - typical colonies for identification. │V - 2. No typical colonies. │IV - IV. Replace plate in incubator for an additional 18 to 24 │ - hours; then, whether colonies appear typical or not, │ - select at least two of those which most nearly resemble B.│ - coli. │V - V. Transfer each colony fished to: │ - 1. Lactose broth fermentation tube; incubate not more │ - than 48 hours at 37° C. Observe gas-formation. │None - 2. Agar slant; incubate 48 hours at 37° C. │ - (a) If gas formed in lactose broth tube inoculated│ - with corresponding culture │VI - (b) If no gas formed in corresponding lactose │ - broth tube, test is completed and negative. │None - VI. Make stained cover-slip or slide preparation, and │ - examine microscopically. │ - 1. If preparation shows non-spore-forming bacilli in │ - apparently pure culture, demonstration of B. coli is │ - completed. │None - 2. If preparation fails to show non-spore-forming │ - bacilli or shows them mixed with spore-bearing forms │ - or bacteria of other morphology. │VII - VII. Replate, to obtain assuredly pure culture, select │ - several colonies of bacilli and repeat steps V and VI. │ - ────────────────────────────────────────────────────────────┴───────── - -In order that tests for B. coli may have quantitative significance, the -following general principles and rules should be observed: - -Ordinarily not less than three portions of each sample should be tested, -the portions being even decimal multiples or fractions of a cubic -centimeter; for example, 10 cc., 1 cc., 0.1 cc., .01 cc., etc. It is -essential that the dilutions should be such that the largest amount -gives a positive test (unless the water is such as to give negative -tests in 10 cc.), and the smallest dilution, a negative result. To -insure this result, it is often necessary to plant four or five -dilutions, especially in the examination of a sample of entirely unknown -quality. The quantitative value of a series of tests is lost, unless all -or at least a large proportion of the smallest dilutions tested have -given negative results. - -In reporting a single test, it is preferable merely to record results as -observed, indicating the amounts tested and the result in each, rather -than to attempt expression of the result in numbers of B. coli per cc. -In summarizing the results of a series of tests, however, it is -desirable, for the sake of simplicity, to express the results in terms -of the numbers of B. coli per cc., or per 100 cc. To convert results of -fermentation tests to this form, the result of each test is recorded as -indicating a number of B. coli per cc. equal to the reciprocal of the -smallest decimal or multiple fraction of a cubic centimeter giving a -positive result. For example, the result: 10 cc. +; 1 cc. +; 0.1 cc. -; -would be recorded as indicating one B. coli per cc. An exception should -be made in the case where a negative result is obtained in an amount -larger than the smallest portion giving a positive result; for example, -in a result such as: 10 cc. +; 1 cc. -; 0.1 cc. +. In such case, the -result should be recorded as indicating a number of B. coli per cc. -equal to the reciprocal of the dilution next larger than the smallest -one giving a positive test, this being a more probable result. - -Where tests are made in amounts larger than 1 cc., giving average -results less than one B. coli per cc., it is more convenient to express -results in terms of the numbers of B. coli per 100 cc. - -The following table illustrates the method of recording and averaging -results of B. coli tests: - - Result of Tests in Amounts Designated. Indicated Number of B. - coli. - 10 cc. 1 cc. 0.1 cc. .01 cc. per cc. per 100 cc. - + − − − 0.1 10. - + + − − 1.0 100. - + + + − 10.0 1,000. - + + + + 100.0 10,000. - + + − + 10.0 1,000. - ————— ————— - Totals (for estimating averages) 121.1 12,110. - Average of 5 tests 24.0 2,422. - -The above method of expressing results is not mathematically altogether -correct. The average number of B. coli per cc., as thus estimated, is -not precisely the most probable number calculated by application of the -theory of probability.[220] To apply this theory to a correct -mathematical solution of any considerable series of results involves, -however, mathematical calculations so complex as to be impracticable of -application in general practice. The simpler method given is therefore -considered preferable, since it is easily applied and the results so -expressed are readily comprehensible. - -In order that results as reported may be checked and carefully valuated, -it is necessary that the report should show not only the average number -of B. coli per cc., but also the number of samples examined; and, for -each dilution, the total number of tests made, and the number (or per -cent.) positive. - - - 10. INTERPRETATION OF RESULTS. - -While it is not within the province of this report to suggest the proper -interpretation of results obtained by the use of the methods herein -specified as standard, the committee feels that a word of caution should -be given regarding the significance of the presence in a water of -members of the B. coli group as defined in this report. Recent work -seems to indicate that the B. coli group as herein defined consists of -organisms of both fecal and non-fecal origin. Therefore care must be -exercised in judging the sanitary quality of a water solely from the -determination of the presence of members of the group. - - - 11. DIFFERENTIATION OF FECAL FROM NON-FECAL MEMBERS OF THE B. COLI - GROUP. - -(1) At least 10 cultures should be used. If possible these should be -subcultured from plates made direct from the water since all of the -cultures obtained by plating from fermentation tubes may be descendants -of a single cell in the water. If cultures from water plates are not -available those obtained from plates made as prescribed under B (p. 101) -may be used. - -(2) Inoculate each culture into dextrose potassium phosphate broth,[H] -adonite broth, and gelatin. For additional confirmatory evidence -inoculation may be made into tryptophane broth,[I] and saccharose broth. -The dextrose broth must be incubated at 30°. Other sugar broths may be -incubated at 30° or 37° as convenient. Gelatin should be incubated at -20°. - -Footnote H: - - (a) _Peptone Medium for the Methyl Red Test. To Make One Liter._ - - 1. To 800 cc. of distilled water add 5 grams of Proteose-Peptone, - Difco., or Witte’s Peptone (other peptones should not be substituted), - 5 grams c. p. dextrose, and 5 grams dipotassium hydrogen phosphate - (K_{2}HPO_{4}). A dilute solution of the K_{2}HPO_{4} should give a - distinct pink with phenolphthalein. - - 2. Heat with occasional stirring over steam for twenty minutes. - - 3. Filter through folded filter paper, cool to 20° C. and dilute to - 1,000 cc. with distilled water. - - 4. Distribute 10 cc. portions in sterilized test-tubes. - - 5. Sterilize by the intermittent method for 20 minutes on three - successive days. - -Footnote I: - - _Tryptophane Broth for Indol Test._ - - To 1,000 cc. of distilled water add 0.3 gram tryptophane, 5 grams - dipotassium hydrogen phosphate (K_{2}HPO_{4}), and 1 gram peptone. - Heat until ingredients are thoroughly dissolved, tube (6 to 8 cc.), - and sterilize in autoclave for 15 minutes after the pressure reaches - 15 pounds. Some American peptones are standardized to contain a - uniform amount of tryptophane. If such peptone is used the tryptophane - in the above formula may be omitted and the peptone increased to 5 - grams. - -(3) After 48 hours record gas formation in adonite and saccharose -broths. Determine indol formation in tryptophane broth by adding drop by -drop, to avoid mixing with the medium, about 1 cc. of a 2 per cent. -alcoholic solution of p-dimethyl amido-benzaldehyd, then a few drops of -concentrated hydrochloric acid. The presence of indol is indicated by a -red color which is soluble in chloroform. There may be some unconverted -tryptophane still present which will give a distinctly blue color which -is insoluble in chloroform. A mixture of the two will be either blue or -violet. If from such a mixture of colors the red of indol be extracted -with chloroform proof of the presence of indol will be complete. - -(4) After 5 days apply methyl red test and Voges-Proskauer test to -dextrose broth. - - - _Methyl Red Test._[J] - -Indicator solution.—Dissolve 0.1 gram methyl red in 300 cc. alcohol and -dilute to 500 cc. with distilled water. - -Footnote J: - - (b) _Synthetic Medium for the Methyl Red Test._ To Make One Liter. - Dissolve 7 grams Na_{2}HPO_{4} (anhydrous) or 8.8 grams - Na_{2}HPO_{4}.2H_{2}O, 2 grams KHphthalate, 1 gram aspartic acid, and - 4 grams dextrose in about 800 cc. of warm distilled water. When - solution is complete, cool and make up to 1 liter at room temperature. - Heat in an autoclave for 15 minutes after the pressure has reached 15 - pounds, provided the total time of exposure to heat is not more than - one-half hour. The hydrogen-ion concentration of the medium is fixed - by the composition. It should be very close to P_{H} 7.0, slightly red - with phenol red. All materials should be recrystallized or if used - from stock furnished by manufacturers, should be carefully examined. - The di-sodium hydrogen phosphate may be used either as the anhydrous - salt obtained by dessication in vacuo at 100° C. or else as the salt - containing two molecules of water of crystallization. This is obtained - by exposing the recrystallized Na_{2}HPO_{4}.12H_{2}O for two weeks. - Use 0.88 per cent. of Na_{2}HPO_{4}.2H_{2}O. - -Procedure in test.—1. To 5 cc. of each culture add 5 drops of methyl red -solution. - -2. Record distinct red color as methyl red +, distinct yellow color as -methyl red -, and intermediate colors as ?. - - - _Voges-Proskauer Test._[216] - -To the remaining 5 cc. of medium add 5 cc. of a 10 per cent. solution of -potassium hydroxide. Allow to stand over night. A positive test is -indicated by an eosin pink color. - -(5) Gelatin tubes should not be pronounced negative until they have been -incubated at least 15 days. - -The following group reactions indicate the source of the culture with a -high degree of probability: - - Methyl red + │B. coli of fecal origin. - Voges-Proskauer − │ - Gelatin − │ - Adonite − │ - Indol, usually + │ - Saccharose, usually −│ - - Methyl red − │B. aërogenes of fecal origin. - Voges-Proskauer + │ - Gelatin − │ - Adonite + │ - Indol, usually − │ - Saccharose + │ - - Methyl red − │B. aërogenes, probably not of fecal - │ origin. - Voges-Proskauer + │ - Gelatin − │ - Adonite − │ - Indol, usually − │ - Saccharose + │ - - Methyl red − │B. cloacae, may or may not be of fecal - │ origin. - Voges-Proskauer + │ - Gelatin + │ - Adonite + │ - Indol, usually − │ - Saccharose + │ - - - 12. ROUTINE PROCEDURE FOR EXAMINATION OF SAMPLES OF WATER. - -_First Day_: - - 1. Prepare dilutions as required. - - 2. Make two (2) gelatin plates from each dilution, and incubate at - 20° C. - - 3. Make two (2) agar plates from each dilution, and incubate at 37° - C. - - 4. Inoculate lactose broth fermentation tubes with appropriate - amounts for B. coli tests, inoculating two (2) tubes with each - amount. - -Note:—Where repeated tests are made of water from the same source, as is -customary in the control of public supplies, it is not necessary to make -duplicate plates or fermentation tubes in each dilution. It is -sufficient, in such circumstances, to make duplicate plates only from -the dilution which will most probably give from 25 to 250 colonies per -plate. - -_Second Day_: - - 1. Count the agar plates made on the first day. - - 2. Record the number of lactose broth fermentation tubes which show - 10 per cent. (10%) or more of gas. - -Note:—In case only the presumptive test for B. coli is required, -fermentation tubes showing more than 10 per cent. (10%) of gas at this -time may be discarded. - -_Third Day_: - - 1. Count gelatin plates made on first day. - - 2. Record the number of additional fermentation tubes which show 10 - per cent. (10%) or more of gas. - - 3. Make a lactose-litmus-agar or Endo’s medium plate from the - smallest portion of each sample showing gas. Incubate plate at 37° - C. - -Note:—In case the smallest portion in which gas has been formed shows -less than 10 per cent. (10%) of gas, it is well to make a plate also -from the next larger portion, so that, in case the smallest portion -gives a negative end result it may still be possible to demonstrate B. -coli in the next larger dilution. - -_Fourth Day_: - - 1. Examine Endo’s medium or lactose-litmus-agar plates. If typical - colonies have developed, select two and transfer each to a lactose - broth fermentation tube and an agar slant, both of which are to be - incubated at 37° C. - - 2. If no typical B. coli colonies are found, incubate the plates - another 24 hours. - -_Fifth Day_: - - 1. Select at least two colonies, whether typical or not, from the - Endo’s medium or lactose-litmus-agar plates which have been - incubated an additional 24 hours; transfer each to a lactose broth - fermentation tube and an agar slant, and complete the test as for - typical colonies. - - 2. Examine lactose broth fermentation tubes inoculated from plates - on the previous day. Tubes in which gas has been formed may be - discarded after the result has been recorded. Those in which no - gas has formed should be incubated an additional 24 hours. - -_Sixth Day_: - - 1. Examine lactose broth fermentation tubes reincubated the previous - day. - - 2. Examine microscopically agar slants corresponding to lactose - fermentation tubes inoculated from plate colonies and showing - gas-formation. - - - BACTERIOLOGICAL BIBLIOGRAPHY. - -Bibliography 201: - - BOVIE, W. T. A Direct Reading Potentiometer for Measuring and - Recording both the Actual and the Total Reaction of Solutions. _Jour. - Med. Research_, 33, 1915–16, 295. - -Bibliography 202: - - BREED, R. S. and DOTTERRER, W. D. The Number of Colonies Allowable on - Satisfactory Agar Plates. _Jour. of Bact._, 1, 1916, 321. - -Bibliography 203: - - BROWNE, W. W. A Comparative Study of the Smith Fermentation Tube and - the Inverted Vial in the Determination of Sugar Fermentation. _Amer. - Jour. of Public Health_, 3, 1913, 701. - -Bibliography 204: - - CLARK, W. M. An Hydrogen Electrode Vessel. _Jour. Biol. Chem._, 23, - 1915, 475. - -Bibliography 205: - - CLARK, W. M. The “Reaction” of Bacteriological Culture Media. _Jour. - of Inf. Diseases_, 17, 1915, 109. - -Bibliography 206: - - CLARK, W. M. The Final Hydrogen Ion Concentrations of Cultures of - Bacillus Coli. _Science_, n. s. 42, 1915, 71. - -Bibliography 207: - - CLARK, W. M. and LUBS, H. A. Hydrogen Electrode Potentials of - Phthalate, Phosphate, and Borate Buffer Mixtures. _Jour. Biol. Chem._, - 25, 1916, 479. - -Bibliography 208: - - CLARK, W. M. and LUBS, H. A. The Differentiation of Bacteria of the - Colon-Aërogenes Family by the Use of Indicators. _Jour. of Inf. - Diseases_, 17, 1915, 160. - -Bibliography 209: - - ENDO, S. Ueber ein Verfahren zum Nachweis der Typhusbacillen Centbl. - f. Bakt. _Erste Abt._, 35, 1903–4, 109. - -Bibliography 210: - - GILLESPIE, L. J. The Reaction of Soil and Measurements of Hydrogen Ion - Concentration. _Jour. Wash. Acad. of Sciences_, 6, 1916, 7. - -Bibliography 211: - - HILL, H. W. Porous Tops for Petri Dishes. _Jour. Med. Research_, 13, - 1904, 93. - -Bibliography 212: - - HILL, H. W. The Mathematics of the Bacterial Count. _Public Health - Reports and Papers_, 33, 1907, 110. - -Bibliography 213: - - ITANO, A. The Relation of Hydrogen Ion Concentration of Media to the - Proteolytic Activity of Bacillus Subtilis. _Bulletin 167_, 1916, Mass. - Agric. Ex. Station. - -Bibliography 214: - - KENDALL, A. I. and WALKER, A. W. The Isolation of Bacillus Dysenteriae - from Stools. _Jour. Med. Research_, 23, 1910, 481. - -Bibliography 215: - - KINYOUN, J. J. and DEITER, L. V. On the Preparation of Endo’s Medium. - _Amer. Jour. Public Health_, n. s. 2, 1912, 979. - -Bibliography 216: - - LEVINE, M. On the Significance of the Voges-Proskauer Reaction. _Jour. - of Bacteriology_, 1, 1916, 153. - -Bibliography 217: - - LUBS, H. A. and CLARK, W. M. On Some New Indicators for the - Colorimetric Determination of Hydrogen-ion Concentration. _Jour. Wash. - Acad. of Sciences_, 5, 1915, 609. - -Bibliography 218: - - MCCLENDON, J. F. New Hydrogen Electrodes and Rapid Methods of - Determining Hydrogen Ion Concentrations. _Amer. Jour. of Physiology_, - 38, 1915, 180. - -Bibliography 219: - - MCCLENDON, J. F. A Direct Reading Potentiometer for Measuring Hydrogen - Ion Concentrations. _Amer. Jour. of Physiology_, 38, 1915, 186. - -Bibliography 220: - - MCCRADY, M. H. The Numerical Interpretation of Fermentation-tube - Results. _Jour. Inf. Diseases_, 17, 1915, 183. - -Bibliography 221: - - NOYES, H. A. Agar Agar for Bacteriological Use. _Science_, n. s. 44, - 1916, 797. - -Bibliography 222: - - ROGERS, L. A., CLARK, W. M. and DAVIS, B. J. The Colon Group of - Bacteria. _Jour. of Inf. Diseases_, 14, 1914, 411. - -Bibliography 223: - - ROGERS, L. A., CLARK, W. M. and EVANS, A. C. The Characteristics of - Bacteria of the Colon Type Found in Bovine Feces. _Jour. of Inf. - Diseases_, 15, 1914, 99. - -Bibliography 224: - - ROGERS, L. A., CLARK, W. M. and EVANS, A. C. The Characteristics of - Bacteria of the Colon Type Occurring on Grains. _Jour. of Inf. - Diseases_, 17, 1915, 137. - -Bibliography 225: - - SMITH, H. M. The Seaweed Industries of Japan. _Bulletin of the Bureau - of Fisheries_, 24, 1904, 135. - -Bibliography 226: - - SÖRENSEN, S. P. L. Enzymstudien. _Biochem. Ztschr._, 21, 1909, 131 and - 201. - -Bibliography 227: - - WHIPPLE, G. C. On the Necessity of Cultivating Water Bacteria in an - Atmosphere Saturated with Moisture. _Tech. Quart._, 12, 1899, 276. - -Bibliography 228: - - WHITTAKER, H. A. The Source, Manufacture and Composition of Commercial - Agar-agar. _Jour. Amer. Pub. Health Assoc._, n. s. 1, 1911, 632. - -Bibliography 229: - - CLARK, W. M. and LUBS, H. A. The colorimetric determination of the - hydrogen-ion concentration of bacteriological culture media. _Jour. - Wash. Acad. Sciences_, 6, 1916, 483. - -Bibliography 230: - - CLARK, W. M. and LUBS, H. A. The colorimetric determination of - hydrogen-ion concentration and its application in bacteriology. _Jour. - of Bact._, 2, 1919, 1 and 109. - -Bibliography 231: - - COHEN, B. and CLARK, W. M. The growth of certain bacteria in media of - different hydrogen-ion concentrations. _Jour. of Bact._, 4, 1919, 409. - -Bibliography 232: - - FENNEL, E. A. and FISHER, M. A. Adjustment of culture medium - reactions. _Jour. of Inf. Diseases_, 25, 1919, 444. - -Bibliography 233: - - JONES, H. M. A rapid hydrogen-ion electrode method for the - determination of hydrogen-ion concentrations in bacterial cultures or - other turbid or colored solutions. _Jour. of Inf. Diseases_, 25, 1919, - 262. - - - - - INDEX. - - - A. - - Acidity, determination of, 39. - - Acids, mineral, 41. - - Agar, nutrient, 94, 96. - lactose-litmus, 97. - - Alkali carbonates, 39. - - Alkalinity, determination of, 35. - - Albuminoid nitrogen, 20. - - Aluminium sulfate, determination of, 41. - analysis of, 78. - - Aluminium and iron, determination of, 57. - - Ammonia nitrogen, determination of, 15. - - Apparatus, bacteriological, 93. - - Application of colon group tests, 102. - - Arsenic, determination of, 63. - - Azolitmin solution, 96. - - - B. - - Bacillus aërogenes, reactions, 108. - cloacae, reactions, 108. - coli, reactions, 108. - - B. coli group, tests, 100. - application of, 102. - fecal and non-fecal, 106. - summary of tests, 104. - - Bacteriological examination, 93. - bibliography, 110. - - Basicity ratio, 80. - - Bibliography, - bacteriological, 110. - chemical, 82. - microscopical, 91. - - Biochemical oxygen demand, 71. - in sludge and mud, 76. - - Bismuthate method (Mn), 49. - - Boric acid, 63. - - Bottles, sample, 1, 93. - dilution, 93. - - Bromine and iodine, determination of, 61. - - Broth, nutrient, 95. - sugar, 95. - - - C. - - Calcium, determination of, 57. - - Carbon dioxide, determination of, 40. - - Chemical analysis, water and sewage, 1. - bibliography, 82. - - Chemicals, analysis of, 77. - - Chloride, determination of, 41. - - Chlorine, determination of, 64. - - Coefficient of fineness, 8. - - Collection of samples, bacteriological, 93. - chemical, 1. - - Colon group, tests (see “B. coli”), 100. - - Color, determination of, 9. - - Copper, determination of, 53, 55. - - Counting (bacterial), 99. - - Cultural characters of colon group, 108. - - Culture media, 94. - azolitmin solution, 96. - Endo’s medium, 97. - litmus-lactose-agar, 97. - litmus solution, 96. - methyl red test, 107. - nutrient agar, 96. - nutrient broth, 95. - nutrient gelatin, 96. - sterilization, 95. - sugar broth, 95. - titration, 94. - tryptophane broth, 107. - - - D. - - Dilution (bacteriological), 98. - - Dissolved oxygen, 65. - - - E. - - Effluents, relative stability of, 69. - biochemical, oxygen, demand of, 71. - - Endo’s medium, 97. - - Erythrosine indicator, 36. - - Ether—soluble matter, 69. - in sludge and mud, 75. - - Evaporation, 29. - - Expression of results (see under “Results”). - - - F. - - Fat, determination of, 69, 75. - - Fecal and non-fecal members, colon group, 106. - - Fermentation tubes, 93. - - Ferrous sulfide in sludge and mud, 76. - - Ferrous iron, determination of, 47. - - Ferric iron, determination of, 48. - - Fineness, coefficient of, 8. - - - G. - - Gelatin media, 94, 96. - - - H. - - Hardness, determination of, 30. - bicarbonate, 37. - carbonate, 38. - hydroxide, 38. - non-carbonate, 34. - temporary, 34. - - Hydrogen sulfide, determination of, 63. - - Hydrogen-ion determination, 94. - - - I. - - Ignition, loss on, 30. - - Incubation, 99. - - Indol test, broth for, 107. - - Indicators, 36, 94, 107. - - Iodine and bromine, determination of, 61. - - Iron and Aluminium, separation, 57. - analysis of, 79. - - Iron, determination of, 43. - standards, 45. - sulfate, determination of, 41. - analysis of, 81. - - - L. - - Lacmoid indicator, 36. - - Lead, determination of, 51, 55. - - Lime, analysis of, 80. - - Lithium, determination of, 60. - - Litmus reagent, 94. - lactose-agar, 97. - solution, 96. - - - M. - - Manganese, determination of, 48. - - Materials, bacteriological, 93. - - Meat extract, 93. - - Media, culture (see “Culture media”), 94–7, 107. - - Methyl orange indicator, 37. - - Methyl red media, 107. - test, 107. - - Microscopical bibliography, 91. - examination, 89. - - Mineral analysis, 56. - - Moisture in sludge and mud, 74. - - Mud deposits, analysis, 73. - - - N. - - Nessler’s reagent, - color standards, 10. - ammonia determination, 19. - - Nitrogen, 15. - ammonia, 15. - albuminoid, 20. - - Nitrogen, in sludge and mud, 74. - nitrate, 23. - nitrite, 22. - organic, 21. - total, 25. - - Nutrient media (see “Culture media”), 94, 107. - - - O. - - Odor, 12. - - Organic nitrogen, 21. - - Oxygen consumed, 25. - demand, biochemical, 71. - dissolved, 65. - in fresh and sea water (table), 68. - - - P. - - Peptone, authorized brands, 93. - - Persulfate method (Mn), 48. - - Petri dishes, 93. - - Phenoldisulfonic acid method (nitrate), 23. - - Phenolphthalein indicator, 36, 94. - - Physical examination, 4. - - Pipettes, bacteriological, 93. - - Plating, bacteriological, 99. - - Platinum-cobalt color standard, 9. - wire turbidity, 5. - - Potassium, determination of, 59. - - Presumptive tests, colon group, 102. - - - R. - - Reactions of colon group, 108. - - Reaction of culture media, 94. - of sludge and mud, 73. - - Reduction method (nitrate), 24. - - Relative stability method, 71. - - Residue on evaporation, 29. - - Results, expression of, - bacteriological, 103. - chemical examination, 14. - color, 8. - odor, 12. - - Results, interpretation of (bacteriological), 106. - - Routine procedure (bacteriological), 108. - - - S. - - Samples, - bacterial, 93. - bottles, 1. - chemical, 1. - interval before analysis of, 2. - quantity required, 1. - representative, 3. - sludge and mud, 73. - - Sewage sludge, analysis, 73. - - Silica, determination of, 56. - - Soda ash, analysis of, 82. - - Soap method (hardness), 31. - - Sodium and potassium, 58. - - Solids, total, fixed, volatile, 29. - - Specific gravity of sludge and mud, 74. - - Stability, relative, of effluents, 69. - method, relative, 71. - - Standards, - ammonia, 17. - chlorine, 65. - color, 9. - hardness, 32. - iron, 45. - Nessler, color, 10. - platinum-cobalt, 10. - turbidity, 4. - - Sterilization of media, 95. - - Storage of samples, 2, 98. - - Sugars for media, 94. - - Sugar broths, 95. - - Sulfate, K and Na, 58. - - Suspended matter, 30. - - - T. - - Tin, determination of, 54, 55. - - Tintometer, Lovibond, 11. - - Titration of media, 94. - - Total nitrogen, 25. - residue on evaporation, 29. - - Tryptophane broth, 107. - - Turbidity, 4. - coefficient of fineness, 8. - platinum wire method, 5. - rod, graduation, 6. - standard, 4. - turbidimetric method, 7. - turbidometer, graduation, 8. - - - V. - - Voges-Proskauer test, 107. - - Volatile matter, 29. - in sludge and mud, 74. - - - Z. - - Zinc, 52. - ------------------------------------------------------------------------- - - - - - TRANSCRIBER’S NOTES - - - 1. Silently corrected typographical errors and variations in spelling. - 2. Archaic, non-standard, and uncertain spellings retained as printed. - 3. The Chemical Bibliography was reformatted in footnote style. - 4. The Bacteriological Bibliography was reformatted in footnote style - and the numbering was increased by 200. - 5. 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