J u l y , 1916
T H E JOURNAL OF INDL’STRIAL A N D ENGINEERIN G CHEMISTR Y
Mason,’ who has used t h e method extensively, says: “Usually four 50 cc. tubes will be sufficient t o carry off al! the free ammonia, but it is the author’s custom always to distil off six.” Stocks2 says: “In distilling ordinary waters, practically the whole of the ammonia will be present in the first IOO cc., but with sewages the whole of the ammonia may not have been obtained even after distilling 300 cc., and it is, therefore, necessary in such cases to allow the retort to cool, make up to the original volume with distilled water and continue the distillation. The albuminoid ammonia being formed by the oxidation of organic matter, is not evolved so quickly as the free ammonia, hence it may be necessary to distil several IOO cc. portions before it ceases to be evolved.” T h e “ S t a n d a r d Methods of Water Analysis” (1912 Edition) recommends t h e collection of t h r e e j o cc. portions for t h e free ammonia, a n d a t least four, pref- ’ erably five, j o cc. portions f o r albuminoid ammonia. This procedure we were using until we saw a n a d vance copy of the Revision of t h e Standard Methods a n d learned t h a t it was recommending a collection of four j o cc. Nessler t u b e s in t h e distillation of t h e free ammonia a n d five in t h e case of albuminoid ammonia. In order t o see what influence this procedure would have upon t h e results obtained, we began a statistical s t u d y of t h e quantities of ammonia collected in each tube, as well as the total a m o u n t obtained. T h e results of this s t u d y are herein contained. We have been following t h e revised procedure f o r several months, using it on all classes of water. T h e total number of waters examined was between j o o a n d 1000;t h e free ammonia varied from 0 . 0 0 2 t o 2 . o parts per million, a n d t h e albuminoid from 0 . 0 0 2 t o 3 . o p a r t s per million. -1compilation of all of t h e results, with regard t o a m o u n t a n d r a t e of ammonia distilling, were made a n d the conclusions obtained were as follows: 76 24 50 20
75 25 30 20
per per per per
~YITROGENA S FREEAMMOXIA Fourth tube averages 5 per cent of t h e total nitrogen cent of t h e waters had 100 per cent nitrogen in 3 tubes cent of t h e waters had 95 per cent nitrogen in 3 tubes cent of t h e waters had 50 t o 5.5 per cent nitrogen in 1 tube cent of t h e waters h a d 65 to 70 per cent nitrogen in 1 tube
per per per per
NITROGEN A S . ~ L B U M I K O I D AXMONIA F i f t h tube averages 5 per cent of t h e total nitrogen cent of t h e waters had 100 per cent nitrogen in 4 tubes cent of t h e waters had 95 per cent nitrogen in 4 tubes cent of the waters had S O t o 60 per cent nitrogen in 1 tube cent of t h e waters had 60 t o 7 0 per cent nitrogen in 1 tube
Those waters which h a d j per cent of t h e nitrogen in t h e last t u b e h a d a total nitrogen content of either free or albuminoid ammonia of I p a r t per million or more of nitrogen. Since ordinary waters, unless grossly polluted, contain less t h a n I p a r t per million of nitrogen as free or albuminoid ammonia, we can conclude t h a t t h e collection of a 4th t u b e in t h e free ammonia determination a n d a 5th in t h e albuminoid determination, under ordinary circumstances, is n o t necessary. Furthermore, t h e average per cent found in t h e last t u b e , including all samples, was only j per cent of t h e total nitrogen. In a water containing less t h a n I part per million t h e maximum error is 0 . o j p a r t per million; in a water containing 4 parts per million, t h e maximum a m o u n t found in t h e waters examined, t h e error is 0 . z p a r t per million. I n other words, in one case we would report o . 9j p. p. m . of nitrogen a n d in t h e other 3 . 8 0 . “Examination of Water,” 1913, 62. “LT-ater Analysis.” 1912, 11.
603
However, since t h e ammonia determination is not quantitative a n d t h e results are used only as a basis for determining pollution, t h e question t o be decided is whether or not t h e error of 0 . 0 j p. p. m. in one case a n d 0 . 2 in t h e other, would cause a change of judgment. We t h i n k it would n o t ; t h a t is, a water with I p. p. m. of nitrogen would s t a n d as good a chance of being condemned as one containing 0 . 9 5 p. p. m., if all t h e other evidences pointed towards contamination. We conclude, therefore, from this s t u d y t h a t in order t o get sufficient information upon which t o base a judgment, it is not necissary. in ordinary routine water analysis, t o nesslerize more t h a n three 5 0 cc. portions for free ammonia, a n d four 50 cc. portions for albuminoid ammonia WATGRA X D SEWAGE LABORATORY UNIVERSITYOF KANSAS,LAWRENCE
A MODIFICATION OF McCRUDDEN’S METHOD FOR CALCIUM, FOR THE ESTIMATION OF CALCIUM AND STRONTIUM IN THE PRESENCE OF PHOSPHORlC ACID AND A SMALL AMOUNT OF IRON By 0. B. WINTER Received August 11, 1915
T h e methodl generally used in estimating calcium a n d strontium, when both are present in a solution, is t o precipitate t h e m as t h e oxalates, burn t o t h e oxides, change t o t h e nitrates, separate t h e calcium nitrate from t h e strontium nitrate b y means of absolute alcohol a n d ether, and then determine each element separately. If phosphoric acid and iron are also present in t h e solution with t h e calcium a n d s t r o n t i u m salts, t h e separation becomes much more difficult since calcium, strontium and iron phosphates a r e quite insoluble in a neutral or alkaline solution. I n this latter case, t h e phosphoric acid a n d iron are re moved before, t h e calcium and strontium are determined. This is usually accomplished b y precipitating2 t h e phosphoric acid as ferric phosphate. a n d t h e excess of iron as ferric subacetate. However, when there is a large amount of phosphoric acid in t h e solutibn, this method becomes tedious because t h e bulky, gelatinous precipitate formed causes t h e solution t o filter very slowly, a n d i t is almost i m pbssible t o wash all of t h e calcium a n d strontium salts o u t of this precipitate. McCrudden has worked out a method3 for “ T h e quantitative separation of calcium a n d magnesium in the presence of phosphoric acid a n d small a m o u n t s of iron, devised especially for t h e analysis of foods, urine and feces.” B y this method t h e calcium is precipitated very slowly as t h e oxalate in a boiling solution containing a small amount of free hydrochloric acid. This gives rise t o a condition i n which t h e calcium oxalate comes down very coarsely crystalline, a n d apparently no soluble salts are carried down b y occlusion. The above method was found accurate for t h e estimation of calcium, b u t in trying it out on a strontium U. S. Dept. of Agr., Bureau of Chemistry, Bxll. 162, 44 ?
Perkin, “ M e t h o d s in Qual. Analysis.” p . 76.
J . Bid. Chem.. 7 (I909), 83.
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T H E JOURATAL O F I , V D C S T R I A L A N D E X G I N E E R I N G C H E M I S T R Y
1’01. 8, NO. 7
solution, i t was found t h a t this element r a n lorn., BIOCHEMICAL CHANGES IN COTTONSEED IN b u t not so much so as was anticipated. Several STORAGE‘ BY J. R. RATHER different modifications of t h e method were a t t e m p t e d Received March 25, 1916 a n d finally it was shown t h a t t h e addition of alcohol would insure complete precipitation of strontium. T h e investigation here reported is a n outgroa7th T h e following method gave very satisfactory results of a s t u d y of t h e effect of storage on t h e vitality of cottonseed planned a n d conducted by the Departfor both calcium a n d strontium: Dilute t h e solution containing t h e calcium or stron- ment of Agronomy of t h e Arkansas Experiment tium, or both, t o about 2 0 0 cc. and add a few drops of Station. T h e field work gave opportunity t o s t u d y alizarine a n d ammonium hydroxide until t h e solu- changes in t h e seed with reference t o t h e possible tion is faintly alkaline. Now add dilute hydrochloric deterioration from t h e standpoint of t h e feeder of live acid until t h e solution is faintly acid. T o this solu- stock a n d t h e manufacturer of cottonseed oil. With t i o n add I O cc. of 0 . 5 N hydrochloric acid a n d I O cc. this in mind, samples of cottonseed collected in t h e of 2 . j per cent of oxalic acid, a n d boil until t h e pre- work on t h e vitality of cottonseed were examined as ,cipitate becomes coarsely granular. Then a d d satura- described below. t e d ammonium oxalate solution, a few drops a t a time NO mention of t h e biochemical changes which t a k e with constant stirring, until a b o u t twice t h e amount place in stored cottonseed has been found in t h e necessary t o precipitate all t h e calcium a n d strontium literature. I t is common knowledge, however, t h a t has been added. Cool t h e solution, a d d , with constant cottonseed will heat a n d deteriorate in storage under stirring, 8 cc. of 2 0 per cent sodium acetate solution certain conditions. This heating is undesirable from a n d about 1 5 cc. of 9; per cent alcohol, and allow t o t h e standpoint of t h e oil mill because i t leads t o t h e s t a n d from 4 t o 18 hours. Filter a n d wash t h e pre- production of low-grade cot,tonseed oil, d a r k in color cipitate a few times with I per cent ammonium oxalate a n d high in free f a t t y acids. There is a larger loss in solution, several times with I per cent ammonium refining such oil, a n d as cottonseed oil is sold t o t h e oxalate solution containing 20 per cent b y volume of refiners on t h e basis of t h a t factor, t h e oil mills conalcohol, a n d finally a few times with water contain- s t a n t l y watch for heating in their storage bins, a n d ing 20 per cent b y volume of alcohol. S o w burn t h e move t h e heated seed out as rapidly as possible. A precipitate t o t h e oxide, dissolve i n nitric acid, dehy- p r i o r i , t h e n , cottonseed t h a t has heated would be drate, separate t h e calcium nitrate’ from t h e stron- expected t o be high in free f a t t y acids. T h e work of t i u m nitrate b y means of absolute alcohol a n d ether, various investigators on t h e deterioration of corn (maize) in storage2 indicates t h a t cottonseed would a n d determine each element in t h e usual manner. T h a t this modified method gives quantitative re- probably increase also in total acidity under similar sults is shown in t h e accompanying table, which gives conditions. t h e analyses of synthetic solutions of calcium a n d EXPERIMEKTAL strontium salts. T h e amount of calcium in these T h e field work of this investigatipn was conducted solutions was determined b y precipitating it as t h e a t Morrilton, Arkansas, during t h e seasons of 1914 oxalate2 in a neutral solution a n d then burning t o t h e a n d 191j,b y Mr. M. S. Baker of t h e Department of oxide, after first removing t h e phosphoric acid with Agronomy of this Experiment Station. Morrilton is ferric chloride3 a n d t h e excess of iron as ferric subin a typical cotton section of t h e s t a t e , a n d t h e soil acetate. T h e strontium in t h e solutions was estimated selected was a s nearly uniform as possible. as t h e sulfate4 and calculated t o t h e oxide. A five-bale lot of seed cotton, from native Mebane’s RESULTS B Y MODIFIED hlCCRUDDEN M E T H O D Triumph seed, was harvested in mid-season, while dry, G n A l CALCIUM GRAMSTROKTIL-Y OXIDE (CaO) OXIDE (SrO) PsOj + a n d stored t h e same d a y in a n oil mill seed bin. After Found Present Found No. FrxOa Present 1 Absent ,... .... 0.0493 0.0494 0.0496 0.0498 a storage period of 2 1 days it was ginned, a n d t h e 2 Absent .... . I . . 0.1464 0.1460 0.1467 . . . . 3 Present 0.0991 0.0995 0.0994 . . . . seed (5000 lbs.) stored in a pile 1 2 ft. b y 1 2 ft. b y 6 ft. 4 Present 0:0908 0:09Oi 0.0911 .... in a n oil mill seed bin for a period of 7 7 days. Samples 5 Absent 0.1004 0.0957 0.1003 O:O7i2 0:0?280 : b ? 3 0 . , . . 6 Present 0,0454 0.0450 0.0495 0.0490 . . . . .... were t a k e n immediately after harvest, when t h e seed S C RI 21A R Y was ginned, a n d whenever t h e temperature of t h e I-hlccrudden’s method with t h e modifications seed seemed t o warrant it. I n sampling t h e cottongiven in this paper may be used for determining cal- seed a sampler wa,s used which took t h e sample from t o p t o b o t t o m of t h e bin a t t h e point desired. F o u r cium or strontium. 11-This modified ’McCrudden method is accurate thermometers were placed in different parts of t h e bin a n d convenient f o r determining calcium and strontium a n d accurate records kept of t h e changes in temperawhen both are present in a solution containing phos- t u r e . T h e samples were forwarded t o t h e laboratory in air-tight containers, a n d as soon as possible after phoric acid and a small amount of iron. their arrival a portion of each was ground for analysis. MICHIGANAGRICULTURAL COLLEGE E x P E n I x E x T S T A T I O N EASTLANSING,MICHIGAN Moisture, f a t , free f a t t y acids in f a t , crude protein, 1 IJ. S. Dept. of Agr., Bureau of Chemistry, Bd1, 162, 44. albuminoids, a n d total acidity determinations were
I Treadwell-Hall, “Analytical Chem. ”: “ Quant. Analyses,” 1st Ed., 2 (1909). 65. a Perkin, “Methods in Qual. Analysis,” p. 76. Treadwell-Hall, “Analytical Chem.”: “ Quant. Analyses,” 1st. Ed., 2 (1909). 66.
1 Full details of these and additional experiments will be published as a Bulletin of the Arkansas Experiment Station. 2 See Black and Alsberg Bur. Plant Ind.. U. S. Dept. Agr., Bull. 199; Besley and Baston, U.5. Dept. Agr., Bull. 102; and references there given.
