Kov., 1914
T H E J O U R N A L OF I N D C S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
acid mixture, yields glucose a n d a resin b y boiling with dilute sulfuric acid. F r o m t h e roots of wheat seedlings t h e r e was obtained, b y extraction m,ith h o t waterand hot alcohol and precipitation f r o m alcohol b y of ether, material which gave a greenish b l u e color
with and acid; a “lor with phenol’ acid and a little potassium chlorate; a reducing substance on boiling with dilute Sulfuric acid. T h e method of obtaining t h e material. i t s reaction with phenol, a n d t h e formation of reducing substances on boiling with acid mould indicate t h e presence of coniferin in t h e wheat roots. Coniferin, i t might be said i n passing, has been found in t h e lignified tissue of a n u m b e r of plants. Vanillin we have found also i n rotten oak wood, in pineapple pulp a n d parings a n d in t h e hot water extract of lawn grass, consisting of blue grass a n d a small a m o u n t of white clover. T h e a m o u n t of vanillin extractable from grass is considerably increased b y heating with j per cent sulfuric acid for 4 hours on a steam b a t h . Undoubtedly i t occurs t o a greater or less degree in m a n y plants either free or in a conjugated form, from which i t m a y be liberated by oxidation a n d hydrolysis. I t s presence in wood and various forms of vegetation would lead t o t h e conclusion t h a t t h e vanillin in soil has i t s origin in vegetable dkbris a n d t o a minor degree also in direct excretion or cell sloughing b y growing plants. SOIL
FERTILITY INVESTIGATIONS, BUREAUOF U. s. DEPARTXENT O F AGRICULTURE WASHINGTON
SOILS
AN EXACT AND EASY METHOD FOR PREPARING A NEUTRAL. AMMONIUM CITRATE SOLUTION By J. M. MCCANDLESS Received August 8. 1914
Since t h e writer made his official report as Referee on Phosphoric Acid. in 1908 t o t h e Association of Official Agricultural Chemists, there have appeared a n u m b e r of interesting articles on t h e subject m a t t e r of t h a t report showing how t h e a m m o n i u m citrate solution could be rendered neutral b o t h b y physical a n d chemical methods. All of this work has confirmed t h e accuracy of t h e work done, a n d t h e conclusions reached b y t h e writer in his original report. As this report was never published i n a n y chemical journal, being printed only in t h e Proceedings of t h e A. 0.A. C., a n d has therefore never been seen b y m a n y who are interested in t h e subject, t h e writer m a y be pardoned for reproducing here a p a r t of t h a t report. P A R T I A L REPRODUCTION OF REPORT OF REFEREE O N PHOSPHORIC ACID FOR
1908
“As the referee was to decide whether the various solutions
of ammonium citrate sent him were neutral or not, and as scarcely any two chemists can agree upon the exact point of neutrality, whether from lack of sensitiveness of the indicators, or color-blindness on the part of the operators, he decided to make an analysis of each sample according to the method outlined in his last report to the Association, and he guided by those results in deciding upon neutrality. METHOD OF ANALYSIS-“Twenty-five CC. O f each Solution were pipetted into a 250 cc. flask, diluted to mark, shaken, and 2 5 cc. of this solution were pipetted into a distillation flask. To the 1
Bur. of Chem , U. S. Dept. of Agr., Bull. 132, 11
921
solution in the flask, 40 cc. A7/4 caustic soda solution were added, and the contents of the flask distilled into 2 0 Cc. N / 2 acid, continuing the distillation till the Volume of the distillate measured from 6 j to 70 cc. The ammonia in the distillate was then titrated by means of N/IO alkali and cochineal. The residue in the distillation flask was washed into an Erlenmeyer, excess of standard acid added, a few drops of phenolphthalein, and the excess acid estimated by N/IO alkali. From the result, the weight of citric acid originally combined with the ammonia was calculated. Calculating from the formula of the pure salt, (NH4)3C6HjO1, that the ratio of ammonia to citric acid was as I : 3.765, a basis of comparison was established. Results obtained are given in table below: Milligrams Milliof citric grams of acid in ammonia 25 cc. of in 25 cc. diluted of diluted soluXumber solution = tion = of 2 1 / 2 cc. 2 1 / 2 cc. analvst orieinal orieinal 433.2 113.9 412.8 109.3 424.96 104.9 433.9 113.7 110.5 430.08 111.5 436.48 108.7 421.1 104.7 398.7 102.8 430.7
Ratio qf ammonia t o citric acid 1: 3.803 1: 3 , 7 7 5 1:4 . 0 5 1 1:3.816 I :3.891 133.915 1: 3.874 1: 3.808 1:4.189
Ratio in neutral salt (NHd3CsHsO; 1: 3.765 1 :3 . 7 6 5 1: 3 . 7 6 5 1:3.765 1: 3 . 7 6 5 1:3.765 1:3.765 1:3.765 1:3.765
REACTION WITH
CORALLIN N-eutral Alkaline Neutral Acid Slightly acid Arid Slightly acid Neutral Acid
“In the above table, all the solutions which showed materially more citric acid than 3.765 parts to I of ammonia, also showed a decidedly acid reaction t o corallin “It appears that some chemists prepare their ammonium citrate solution by treating the citric acid with excess of ammonia, and then leave the hot solution to neutralize itself, or finally adjust by means of red and blue litmus paper, or corallin. No. 3 in the above table was prepared in this way. The heat of the mixture not only drove off sufficient ammonia to render it neutral, hut continued and left it decidedly acid.” T h e writer has, only in t h e past few days, h a d his attention called t o t h e article of P a t t e n a n d Marti’ where in referring t o t h e solutions, analyses of which are given i n t h e above table, t h e y use t h e following language: “ T h e three solutions claimed t o be neutral a n d 168.76 g. b y McCandless contained 44.3 g . “3, C6Hg07 per liter, t h e ratio being 1:3.809. T h e results obtained b y us conclusively prove t h a t such a solution would be slightly acid, ’which fact is further substantia t e d b y t h e ratio of ammonia t o anhydrous citric acid being t o o wide.” P a t t e n a n d M a r t i h a d evidently failed t o note t h e headings of Columns j a n d 6 in t h e above table, o r t h e y would not have a t t r i b u t e d t o t h e writer t h e “CLAIM” t h a t solutions Nos. I, 4 a n d 8 were really neutral, since t h e heading of Column 6 expressly s t a t e d t h a t t h e words “neutral,” “acid” a n d “alkaline” i n t h e column below referred t o t h e reactions with corallin, a n d t h e heading of Column j showed t h a t t h e only ratio of ammonia t o citric acid which t h e referee recognized as being neutral was t h a t of I : 3.76j. T h e method given b y P a t t e n a n d h l a r t i is a n i n teresting a n d excellent method of preparing a neutral solution. T h e writer proposes the following exact a n d easy method of making a neutral solution of a m m o n i u m citrate which involves n o analyses o r distillations, b u t only a couple of titrations with solutions always r e a d y in every laboratory: 1
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P R O P O S E D METHOD
Carefully sample t h e lot of citric acid on h a n d , b y grinding a sufficient q u a n t i t y t o get a n average sample t h r o u g h a coffee or other suitable mill. Mix thoroughly, a n d weigh 7 g. into a liter flask. Dissolve in water, a n d dilute t o m a r k . Pipette out 50 cc. or 0 . 3 j g. of t h e citric acid, a n d t i t r a t e with N / I O caustic soda a n d phenolphthalein. If t h e acid is pure a n d uneffloresced, just 50 cc. of N / I Oalkali will be required. Weigh 1 8 5 0 g. of pure uneffloresced acid or its equivalent in acid value of effloresced or i m p u r e acid into a large bottle or carboy, a n d cover with 7 liters of cold water. Calculate t h e exact number of g. of anhydrous citric acid present. R u n from a burette 2 5 cc. of concentrated ammonia into a 500 cc. flask containing cold distilled water. Dilute t o mark a n d mix. Carefully measure 2 5 cc. of this solution a n d t i t r a t e with N/2 acid a n d methyl orange. Calculate t h e volume of concentrated ammonia necessary t o neutralize t h e citric acid in t h e ratio of I of a m monia t o 3.763 of anhydrous citric acid. (If a stock of approximately I O per cent ammonia is on h a n d , i t is perhaps preferable t o use i t instead of concentrated ammonia using, of course, a correspondingly suitable volume of water for t h e citric acid.) Add t h e carefully measured ammonia solution t o thecitric acid i n t h e bottle or carboy, close immediately with a tightly fitting rubber stopper, a n d shake till t h e acid is dissolved; allow t o s t a n d tightly stoppered until cold, t h e n shake again before removing t h e stopper. Bring t o a gravity of 1.09 a t 20’ C. T h e volume of t h e solution should approximate I O liters. T h e accuracy of t h e solution may be confirmed if desired, b y analysis, using either t h e distillation method already described in this paper, or t h e method of P a t t e n a n d Marti,’ or t h a t of E a s t m a n a n d Hildebrand.2 It was suggested b y one of m y associates t h a t we a t t e m p t t o prepare t h e pure salt, tri-ammonium citrate, a n d determine t h e ratio of ammonia t o citric acid in it. As anticipated it was found impossible t o prepare, b y evaporation a n d crystallization, b u t b y adding t o a solution of ammonium citrate made distinctly alkaline with ammonia, a large excess of strong alcohol, a salt was precipitated which on standing over night became beautifully crystalline. The supernatant liquid was filtered o f f , a n d t h e crystals washed thoroughly on t h e p u m p with a large excess of strong alcohol; t h e mass which was a felt of interlaced crystals, was dried quickly b y pressure between blotting pads, a n d a portion dissolved in water; its reaction with corallin was distinctly alkaline, a n d a n analysis of t h e solution showed t h e ratio of ammonia t o citric acid t o be I t o 3 . 7 6 8 . T h e remainder of t h e crystals left exposed over night t o the s u m m e r t e m p e r a t u r e of t h e laboratory h a d entirely changed t h e n a t u r e of its crystalline structure, a n d a portion of i t , when dissolved in water a n d tested with corallin, was decidedly acid t o t h a t reagent a n d upon analysis showed a ratio of I t o 3.94. It is evident, therefore, t h a t t h e normal salt is not entirely hypothetical, t h a t i t can be actually 1
THISJOURNAL,6 (1913). 567.
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I b i d . . 6 (1914). 577.
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prepared a n d dissolved in water, a n d its solution t h e n shows a n alkaline reaction t o corallin a n d has very nearly t h e ratio of I of ammonia t o 3 . 7 6 5 of citric acid. There seems little reason t o d o u b t t h a t t h e neutral a m m o n i u m citrate solution which t h e A . 0. A . C. h a s been prescribing since t h e d a t e of its organization m a n y years ago, a n d which able a n d conscientious chemists have ever since been earnestly trying t o make exactly neutral, succeeding sometimes perhaps b y accident, but usually only approximating i t , was really intended t o be a solution of t h e normal salt. This opinion was expressed b y t h e writer in his report as Referee in t h e following words: “While t h e referee has a strong conviction t h a t t h e only proper method of making the solution is b y analysis a n d calculation of t h e exact quantity of ammonia a n d citric acid t o be added t o i t , still he hesitates t o urge i t officially, as no w o r k has yet been done b y a n y other referee along this line, a n d because t h e referee is himself no longer a n official chemist.” I n this opinion he has since been supported b y those who have given t h e most earnest t h o u g h t a n d painstaking experiment t o t h e subject, as P a t t e n a n d Marti, E a s t m a n a n d ‘Hildebrand a n d others. T h e laboratory with which t h e writer is identified still makes its solution &s prescribed b y t h e A. 0. A. C., approximating neutrality as closely a s possible b y t h e use of corallin, since t h a t is still one of t h e legal a g d official methods, b u t the writer knows of other chemists who have already a d o p t e d t h e neutralization b y analysis, a n d it is little wonder t h a t under these conditions analyses for available phosphoric acid on t a n k a g e s a n d bone meals, a n d fertilizers containing those ingredients should v a r y quite widely. Let us hope t h a t t h e A. 0. A . C. a t their next meeting will conclude t h a t t h e subject has been investigated long enough, a n d t a k e some definite action a t t h a t meeting, or else appoint a small committee in whom they have confidence, with power t o act in prescribing a m e t h o d which shall be legal a n d official after a definite d a t e . MCCANDLESS LABORATORY ATLANTA, GA.
THE INFLUENCE OF FINENESS UPON THE AVAILABITJTY OF BONE MEAL By S. S. PECK Received July 6, 1914
It has been thoroughly established t h a t the availability of raw phosphate rock or of basic slag depends primarily on its fineness of subdivision. These t w o purveyors of phosphoric acid a n d bones or bone meal comprise t h e three forms in which insoluble phosphoric acid is supplied in fertilizers. I n t h e case of basic slag, t h e phosphoric acid exists as a tetra-calcic or a four-lime phosphate. I n phosphate rock a n d bones t h e phosphoric acid is combined with three parts of lime, a n d is known as tri-calcic phosphate, t o which t h e general t e r m of bone phosphate is applied. As superphosphate, phosphoric acid is supplied in a form soluble in water. It is termed available not because after being applied t o t h e soil i t remains permanently soluble b u t because i t is fixed in a finely divided
