488
T H E J O L; R,lr..i L O F ILVD U S T RI -4L A-VD ENGILVEERILVGC H E M I S T R Y
parable, t h e a m o u n t s of phosphate rock in t h e d u n g of cow K O . 30 a n d of t h e blue heifer were calculated from t h e analyses given in Table 111. Table IT gives t h e quantities of t h e various materials t a k e n , t h e a m o u n t of o I per cent citric acid used as a solvent, a n d t h e percentages of P 2 0 5 found. T h e finely ground phosphate used throughout contained 3 2 . c per cent of P?Oj. T h e citric acid solution mas shaken u p in contact with t h e material for t w o d a y s a n d filtered, a n d t h e PZOS in t h e filtrate determined. F r o m these determinations t h e calculation was made t h a t t h e combined action of t h e ensilage process a n d t h e process of animal digestion resulted i n a n increase of 0 . 9 3 pound of PzOj per I O O pounds of t h e rock in t h e case of t h e cow a n d 1.17 pounds in t h e case of t h e TABLEIV-PHOSPHORIC ACID
SOLUBLEIN CITRIC ACID
(P20,)
CENT
1000 Cc. OF 0 1 PER
All percentages are calculated on a uniform basis of moisture-free a n d phosphate-free manure, z e , the plain manure from the unphosphated feed (15 0 grams) IS taken as the basis of comparison Quantity used for analysis P205 (Water-free basis) found Grams Per cent Material D u n g from cow No. 10 (unphosphated ensilage) 15.0 0.76 Dung from cow No. 10. . . . . . . . . . . . . . . . . . . . . . . . 15.0 Phosphate rock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 . 7 137 O ’ 88 D u n g from cow N o . 30 (phosphated ensilage).. . 17.7137 1.05 D u n g from fawn heifer (unphosphated ensilage) 15 . O I .38 D u n g from fawn heifer.. . . . . . . . . . . . . . . . . . . . . . 15 . O Phosphate rock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9256 .4i D u n g from blue heifer (phosphated ensilage). . . . . 19.9256 1.86 NoTEs-~--A water solution of manure is normally alkaline and hence much of the “available” PzOj is in a precipitated form. Only a slightly acid solution is necessary in order t o get a marked increase in soluble P 2 0 ~ ’-If manure be treated with a 0.1 per cent citric acid solution in the proportions used, the solution is a p t t o become alkaline in the course of a few days, due to the production of NHI b y bacteria; hence long standing must be avoided.
1
1
heifer. T h e increase in soluble P20j was, therefore, very small. On t h e assumption t h a t all of t h e phosphoric acid was voided in t h e dung, these results, t a k e n into consideration with those of Forbes a n d Fritz, indicate a reversion of t h e P205 made soluble b y t h e ensilage. S U 11 M A R Y
I-From calculations based on work reported b y Forbes a n d Fritz, 2 2 . 6 5 per cent of t h e total phosphoric acid of phosphate rock (floats) was rendered soluble i n 0 . 2 per cent HC1 through t h e ensilage process, I p a r t of rock being used t o 2 5 0 p a r t s of green silage corn. a-Feeding experiments b y t h e a u t h o r proved t h a t when 2 pounds of finely ground phosphate rock were mixed with I O O pounds of green silage corn at t i m e of filling of t h e silo, t h e resultant ensilage, though excellent in odor a n d appearance, was not suitable t o be fed in ordinary a m o u n t s , t h e animals soon refusing to eat it. 3-The solubility in 0 . I per cent citric acid of t h e P206 of t h e phosphate rock in t h e dung of t h e animals fed phosphated ensilage mas increased only 3 . 28 per cent of t h e t o t a l PZOj as a n average of tn-o trials. 4-Based on t h e assumption t h a t all of t h e phosphoric acid was voided in t h e dung, t h e d a t a a t h a n d indicate t h a t a reversion of t h e soluble P205took place during t h e process of animal digestion. S-The general conclusion is indicated t h a t t h e silo does not offer a practical means of making t h e P205 of phosphate rock available for plant use. AGRICULTURAL EXPERIMENT STATIOX UNIVERSITYOF TENWESSEE KNOXVILLE
.
Vol. 6, KO. 6
THE THEORETICAL BASIS FOR THE PROPORTIONS OF LIME AND SULFUR USED IN THE COMMERCIAL PREPARATION OF THE LIME-SULFUR SPRAY By HER31.4N
V. TARTAR
Received March 11, 1914
Various formulas (i. e . , proportions of lime, sulfur a n d water) have been recommended for use in t h e preparation of t h e commercial lime-sulfur spray. I n t h e early literature on this subject, t h e proportions of lime ( C a O ) a n d sulfur v a r y within wide limits; t h e more recent work’ shows t h e proper ratio of lime t o sulfur t o be approximately I : Z . There are, however, some differences still existing among t h e recommendations made in this connection b y t h e different agricultural experiment stations. It is well known, too, t h a t various factors such as concentration a n d length of time of boiling, have a n influence on t h e a m o u n t s of lime a n d sulfur required. E v e n t h e length of time of cooling, following t h e boiling period, modifies t h e composition of t h e solution a n d consequently t h e requirements of raw material. For example, in one of t h e experiments a t our local station plant where 108 gallons of material were prepared. a sample t a k e n a n d immediately cooled just a t t h e close of t h e cooking period h a d a gravity of 33O, while one t a k e n after t h e solution h a d cooled i n t h e t a n k for 1 2 hours, h a d only a 30’ strength. This decrease in gravity was due, no doubt, t o t h e decomposition of calcium thiosulfate in t h e hot solution. Similar experiments, in which t h e entire solution was cooled immediately after boiling, showed n o decrease in gravity upon standing. Because of these numerous factors which influence t h e composition of t h e spray, t h e formulas given by different investigators have been worked o u t largely b y t h e “cut a n d t r y ” method. Different a m o u n t s of lime, sulfur a n d water have been cooked for various lengths of t i m e a n d from t h e analyses made of t h e resulting solutions a n d sediment (sulfite), t h e formulas have been derived. B u t little, if a n y , attention has been given t o t h e exact chemical’reactions which occur. T o all familiar with this subject, i t is very evident t h a t a n y formula used in making lime-sulfur m u s t necessarily be based on t h e reactions taking place. Investigations carried out in this laboratory2 have shown t h a t these reactions are represented by t h e following equations:
--
(I) 3Ca(OH)? ( 2 ) Cas4 S (3) C a S 2 0 3 +
+
+ ICS
zCaS4
+ CaS203 + 3 H 2 0
Cas6 CaS03
+S
There is also some oxidation of t h e polysulfides when t h e material is exposed t o t h e air b u t this is so slight, under ordinary conditions of commercial preparation, where large, tall cooking v a t s are used, t h a t i t need n o t be considered here. T h e knowledge of t h e exact n a t u r e of these chemical reactions affords a theoretical basis for determining t h e proportions of lime a n d sulfur required in t h e preparation of a given sample of lime1 Cordley, unpublished results of this station: Stewart, Penn. Agr. Exp. Sta., Bul2. 99; Van Slyke, N. Y . Agr. Exp. Sta. (Geneva), Bull. 329. 2 Jour. Amer. Chem. SOC.,27 (1914). 495.
T H E J O l ’ R S d L O F I Y D L - S T R I . 4 L A.VD E S G I S E E R I S G C H E M I S T R Y
J u n e , 1913
.
sulfur. This will be brought o u t in t h e discussion JV hi ch f 011ow s . I t will be seen from t h e equations given above t h a t t h e compounds formed b y t h e reaction between calcium hydroxide a n d sulfur, under ordinary commercial conditions of manufacture, are calcium tetrasulfide, pentasulfide, thiosulfate. a n d sulfite. All of these compounds are readily soluble in water with t h e exception of t h e sulfite. which is comparatively insoluble. This being t r u e , t h e chemical analysis of t h e limesulfur solution shows t h e a m o u n t s of lime (slaked with water t o form hydroxide) a n d sulfur t h a t have reacted in t h e formation of t h e same except t h e a m o u n t s of these substances necessary t o form t h e insoluble sulfite produced. F r o m t h e knowledge of t h e chemical reactions t h a t occur. however, i t is not a difficult m a t t e r t o estimate. from t h e chemical analysis of t h e solution, t h e q u a n t i t y of sulfite which has been formed. Equation ( I ) shows t h a t when calcium hydroxide a n d sulfur combine. one-third of t h e celcium is combined as thiosulfate a n d two-thirds as polysulfide. Since there is no decomposition of t h e polysulfide, t h e q u a n titative estimation of t h e calcium combined in this form gives a means for determining t h e a m o u n t of thiosulfate which has been formed. T h e difference between this tote1 estimated e m o u n t of thiosulfate a n d t h e a m o u n t actually present in t h e solution. is t h e q u a n t i t y t h a t has decomposed; a n d from this d a t a t h e a m o u n t of sulfite can be easily calculated. T h e initial ratio of lime t o sulfur is also easily determined when one knows not only t h e a m o u n t s of calcium a n d sulfur present in a given lime-sulfur solution, b u t also t h e insoluble sulfite produced in t h e preparation of t h e same. T h e analytical methods for determining t h e a m o u n t s of calcium combined a s polysulfide as well as t h e a m o u n t s of other constituents of lime-sulfur, have been very thoroughly worked o u t ’ a n d i t is unnecessary t o discuss t h e m in this paper. T h e actual application of t h e discussion given above is brought o u t in Table I . T h e chemical compositions of several samples of commercial lime-sulfur solution are given; also t h e estimated a m o u n t s of insoluble calcium sulfite formed a n d t h e calculated ratios of lime TABLEI-CHEMICAL
COMPOSITIOS LIME ( C a O )
7
-----
Combined a s
S o . Sr G R . 1,2585 1.3335 1 2825 1 ,2560 1,2820 1.3110
( a ) Not
.
Estimated Poly-Thio- as insol. sulfide sulfate sulfite 9 464 1 , 8 2 0 4 . 0 6 0 13.943 0.672 5 . 1 5 2 11.357 1 . 1 2 0 4 558 10.248 1.008 4 , 1 1 6 11.424 0 , 8 4 0 4 . Xi2 11.802 1 . 1 9 8 4 . 7 0 3 1 0 . 8 3 4 I . 286 4.131 determined
OF
LIME-SVLFUR SOLUTION SULFUR( S )
dilute solutions prepared under commercial conditions. I t is evident, however. from t h e work of Thatcher’ a n d V a n Slyke2 t h a t t h e ratio in this case would be somewhat greater t h a n I : a ; in some cases it would be perhaps I : 2 . 2 j. The theoretical basis given here mill not exactly apply, of course, t o t h e preparation bf small a m o u n t s of solution, s a y I j o gallons or less. where t h e oxidation of t h e polysulfides occurs t o a considerable extent through contact with t h e air. Acknowledgment is due t o N r . R . H . Robinson mho made several of t h e chemical analyses reported above. CHEMIC4L
.4GRICULTUR4L EKPERINEXT STATIOX CORVALLIS. OREGON
L4BOR4TORY.
THE DETERMINATION OF CAMPHOR IN TABLETS AND PILL s ny EDWINDOWZARD Received March 9, 1914
In so far as t h e writer has been able t o learn, the methods used elsewhere for t h e determination of camphor in tablets a n d pills have not pro\*ed satisfactory. For this reason a description of a method is given which has been in use for over five years with satisfactory results: Camphor m a y be rapidly a n d completely removed from tablets a n d pills b y distillation in a current of s t e a m . T h e watery distillate contains both dissolved a n d undissolved camphor, which can be extracted with benzol. By determining t h e optical rotation of t h e benzol solution. t h e a m o u n t of camphor present in t h e tablets or pills can be readily calculated. A special a p p a r a t u s is required for t h e distillation, because a n ordinary condenser cannot be used a s t h e camphor blocks up t h e tube. After a number of trials t h e arrangement shown in t h e figure proved satisfactory. T h e a p p a r a t u s consists of a flask. -1. for generating steam, a second flask, B , for t h e steam distillation. a n d a receiver, C (a retort with t h e t u b e bent as s h o w n ) , for t h e distillate. T h e retort is kept cool b y t w o streams of water ( D a n d E ) . D impinges on t h e wide p a r t of t h e neck, a n d E on t h e extreme e n d of t h e t u b e . which is closed with a rubber stopper fitted with a glass t u b e open a t both e n d s , t h u s every p a r t of t h e retort is kept covered with a film of water, ensuring a complete condensation. T h e large funnel F conveys t h e water t o a sink b y means of a rubber tube. T h e funnel should be kept a b o u t half filled with water, t h e flow of water from t h e funnel being regulated b y pinchcock G. P R O C E D U R E F O R A DETERMISATIOS-.I number of t a b lets or pills containing about z 1 2 t o 3 grams of camphor are placed in t h e flask B . T h e tablets are just covered with water a n d t h e a p p a r a t u s connected. Sufficient water t o cover t h e bottom of t h e t u b e H is placed in t h e retort. T h e water in -4 is now boiled, with I closed. t h e steam passing into B through t h e t u b e , which a1n:ost
_ A -
Combined as Polysulfide 2 6 ,313
3i.498
30.780 2 7 . 926 31.283 31.930 28 980
Esti-
mated Thio- as insol. sulfate sulfite 2 . 0 8 0 2 320 0 . 7 6 8 2 944 1.280 2 604 1 . 1 5 2 2 354 0.960 2 i84 1 . 3 7 0 2 688 1 . 4 7 0 2 360
RATIO CaO : S REOUIRED 1 : 2.00 1 : 2.08 1 : 2.03 1 : 2.04 1 : 2.04 1 : 2.04
1 : 2.01
t o sulfur. T h e results relating t o chemical composition are expressed as grams per I O O cc. of solution T h e d a t a given s h o r t h a t t h e proportion of lime ( C a O ) t o sulfur which react in t h e preparation of t h e more concentrated commercial lime sulfur solutions is b u t a mere trifle greater t h a n I : a . Unfortunately t h e a u t h o r has not h a d opportunity t o examine more 1 J o u r . A m e r . Chem. Soc., 27 (1905). 244; THISJ O U R N A L , 2 (1910), 271; Alich. Agr. Exp. Sta., Tech. Bull. No. 6.
489
1
Jour A m e r Chem S O L ,30 (19081, 63
2 LOC
c1t
