Action of Urea on Calcium Orthophosphates w. WHITTAKER, FRANK0. LUNDSTROM, AND
H. SHI~IP Fertilizer Investigations, Bureau of Chemistry and Soils, Washington, D. C. COLIN
The only special equipment THE m a n u f a c t u r e of Monocalcium phosphate reacts with urea to used conyisted of a set of satumixed fertilizer:, urea is fref o r m urea phosphate and dicalcium phosphaie. rated salt solutions in desiccators quently added to ordinary, T h i s reaciion can be carried out using aqueous arid a constant - t e m p e r a t u r e double, and ammoniated superor alcoholic urea solutions, or the iwo solids in rooin where these were kept. phorphates or to mixtures conthe absence of a n y tisihle liquid phase. 2 I i x These salt solutions were chosen taining them. In some cases to g k e the deqired range of relaurea is added by ammoniating tures containing excess urea tend io become tive humidities as c a 1c u 1a t e d the superpho.phate with a solusticky, while mixtures containing a n excess of the from vapor pressure data taken tion of urea in ammonia. The mono- salt remain dry at ordinary humidities from the International Critical mechanical condition or drillbut lose water of crystallization equivalent to the Tables and from the work of ability of the resulting fertilizer is urea present. Adanis and Merz (1). In some detertnined largely by its hygrocases solutions simultaneously scopicity, and this is governed Attempts to cause urea to react with dicalcium saturated with two salt5 were by the nature of the mixture of phosphate gave negative results. Urea tends to used. E a c h d e s i c c a t o r was salts produced by the reactions accelerate the loss of water of crystallization f r o m placed in the constant-temperathat occur during inanufacture dicalcium phosphate dihydrate at humidities ture room several days before or on subsequent storage. The below that corresponding to the vapor pressure of use to allow the water vapor conmost important phosphatic comcentration to reach the equilibponent of superphosphate and the hydrate. rium value. Air in this room double superphosphate is monoMixtures of fricalcium phosphate and urea are v a s kept in constant motion by c a l c i u m phosphate. On animarkedly less hygroscopic ihan urea if the proa small fan, and the temperature moniation this salt is converted portion of tricalcium phosphate present is about was held constant a t 30°C. * into dicalcium phosphate to a 80 per cent or greater. degree dependent largely on the about 0.2". A t t > m p e r a t u r e recorder mas operated in the amount of ammonia added ( 4 ) . Where large quantities of ammonia are added, important room a t all times to detect any variations tKat might otheramounts of tricalcium phosphate may also be produced. wise have passed unobserved, such as a temporary drop due This paper presents the results of an investigation of the t o the pon-er being off, etc. action of urea on the three orthophosphates of calcium. The ~ I E T H OOF DS ASALYSIS reaction of urea with another important component of superphosphate, calcium sulfate dihydrate, has already been dePhosphorous pentoxide was determined by the volumetric scribed (8). method ( 2 ) , nitrogen by the Gunning method (2A),and calcium by double precipitation, first as the sulfate and finally as hfATERI.4LS AND dPPAR.4TUS the oxalate which was ignited t o calcium oxide. Special Except where otherwiqe noted, the monocalcium phosphate methods used are described later. monohydrate and dicalcium phosphate dihydrate used were h ~ O N O C A L C I C 3 1PHOSPH.4TE A S D UREA Shering Kahlbaum analytical grade. The mono- salt was recry-tallized from phoqphoric acid solution by the method of It was noted early in this investigation that monocalcium Clark (3) and washed with ether before use. Three *amides phosphate monohydrate when shaken with an aqueous urea of tricalcium phosphate were used, two h j drated and one solution appeared to be partly dissolved and partly converted anhydrous. The preparation of these has been described by into some other substance: R o ~ s Jacob, , and Beeson ( 7 ) . S o important difference in Accordingly a nearly saturated aqueous urea solution mas their behavior was noted. rlnalyses of the mono-, di-, and stirred a t room temperature for about 90 minutes \vith an excess tricalcium phosphates showed them to contain the theo- of c. P. monocalcium phosphate monohydrate [Ca(HzP04)z.Hz0 1, retical amounts of CaO, P20s,and water within the accuracy the solid filtered off, and the mother liquor reduced in volume by vacuum evaporation, keeping the temperature below 50" C. of the methods employed. During the evaporation a fine white precipitate separated out. The urea used was c. P. and contained the theoretical Thi> nas filtered off, dried, and analyzed. A large crop of cryamount of nitrogen as shown by analysis. Urea phosphate tnls, produced on cooling the mother liquor, mas washed quickly was prepared by the method of hiatignon, Dode, and Lan- with water, then several times 61th alcohol, and finally with ether. glade ( 5 ) ,recrystallized from alcohol, washed nith ether, and The crystals Tvere then air-dried at a slightly elevated temperature and analyzed. These crystals gave a cloudy solution when dried a t 63" C. An analysis of this material is given in dirsolved in alcohol, probably because of the presence of calcium Table I. Dhosnhates XThich are insoluble in alcohol. In order t o avoid this contamination TABLEI. COMPOSITION OF PRODUCTS OF L-RE.~-MOXOCALCITX PHOSPHATE with calcium phosphat,es, an excess of MONOHYDRATE REACTIOX AND OF PUREUREAPHOSPHATE monocalcium phosphate monohydrate was PPT. ON stirred with an alcoholic urea solution and PCREUREA CRYSTALS FROM CRYSTALS FROM EVIPORATINQ SOLN, the solid filtered off. A crop of crystals PHOSPHATE AQCEOUSSOLN. ALCOHOLIC SOLX. Calcd. Found Ca1cd.o Found Ca1cd.Q Found Ca1cd.Q Found was obtained by simple cooling Of the P?Oj, % ' 44.92 44.81 44.92 42.90 44.92 44.65 52.18 53.98 mother liquor, no evaporation being neces. . . . . . . . . . . . . . . . . . . . . . . . CaO. 7~ 41.20 34.63 sary. These crystals were recrystallized N2, % 17.72 17.72 17.72 17.70 . . . . . . . . . . 1 7. .. 7. 2. 1 7. .. 6. 6. o, 7895 ,, 6635 twice from alcohol, washed several t,imes .... .... .... CaO/P;Os P,OS/~Z 2.535 2.529 2.535 2.424 2.535 2.528 ..... ..... with ether, dried at 63" C. for 1.5 hours, a Calculated on t h e assumption t h a t reaction 1 took place and gave the products indicated. and fjndly analyzed. The monocalcium
I
r\'
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I
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.
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INDUSTRIAL AKD ENGINEERING CHEMISTRY
1308
phosphate used was acid-free as determined by the acetone method (9). The analyses of the white precipitate, the crystals pre ared from aqueous solution, those from the alcoholic solution, antthose of the pure urea phosphate pre ared from phosphoric acid and urea, mentioned under “Materiag and Apparatus,” are given in Table I. For purposes of comparison calculated values are included also. These results indicate that the reaction Ga(H2PO4),.H2O CO(NHJ2 = H , P O U C O ( ~ ” ~ ) ~ CaHPOl H20 (1)
+
+
+
takes place with the production of urea phosphate and dicalcium phosphate. The composition of the white precipitate indicates that it is a mixture of mono- and dicalcium phosphates. This is to be expected since an excess of monocalcium phosphate was used. This reaction provides a means of preparing urea phosphate without the use of phosphoric acid. From the standpoint of fertilizer technology it is desirable to know whether this reaction can occur in the absence of any definite solution phase as would be the case in an actual fertilizer mixture. To clarify this point, slightly more than 0.01 mole of urea was thoroughly mixed with 0.01 mole of monocalcium phosphate monohydrate. Both materials had been passed through a 100-mesh screen. This mixture was kept a t 30” C. for 11 days a t a relative humidity of 64.5 per cent and then extracted with 95 per cent alcohol. The residue was dried, weighed, and analyzed. It was found to contain 53.31 per cent P?o5and 40.40 per cent CaO with a CaO to P205 ratio of 0.7578. These values correspond to the figures for dicalcium phosphate of 52.19 per cent PzOs and 41.20 per cent CaO with a CaO to PZOSratio of 0.7895. If no conversion had occurred, the ratio would have had the value 0.3948. The alcoholic extract was acid to methyl orange and gave a strong test for PzOs but no test for CaO. These results indicate that the reaction was practically complete and confirms the conclusion that the other product of the reaction is dicalcium phosphate.
Vol. 26, No. 12
b e h e e n 46.7 and 64.5 per cent. This does not preclude the probability that the reaction proceeds more rapidly initially at the higher humidities. In other experiments similar to these, as high as 47 per cent of the PzOj has been rendered alcohol soluble. The results over P205indicate that some reaction occurs even in a very dry atmosphere. These experiments are based on the fact that pure monocalcium phosphate monohydrate contains no alcohol-soluble Pzo5 while urea phosphate is readily alcohol-soluble ( 5 ) . Table I1 shows also that all mixtures except that kept over P,Or took up considerable water and became wet or sticky. This condition was caused either by the presence of water derived from the atmosphere or liberated water of crystallization, or both. It is important to know whether this condition can be avoided and what the factors are that produce it. The following experiments were conducted to answer these questions : Mixtures of 100-mesh urea and 100-mesh monocalcium phosphate monohydrate, each totaling 2 grams in weight but in varying mole ratios, were stored a t 30” C. a t a relative humidity of 59.4 per cent. These mixtures were weighed each week and their condition observed for 8 weeks. Table 111shows the final state. Although all mixtures became caked except the one that became definitely wet, the sticky condition did not develop when the ratio of monocalcium phosphate monohydrate to urea was 1 to 1, or greater. Most of the change in weight and condition occurred the first week. The loss of water of crystallization will be discussed later. TABLE111. EFFECTOF PROPORTION OF UREAON CONDITION AND TOTAL WATERCONTEXTOF UREA-MOKOCALCIUM PHOSPHATE MONOHYDRATE MIXTURES AT 59.4 PERCENTRELATIVE HUMIDITY MOLE RATIO
CalH2POd2 -
HzO/CO(XH?)z
CONDITIOS
KATER OF CRYSTS.
Present
Lost
Gram
70
0.1277 0.1154 0.0968 0.0714
51.2 66.6 Gained Gained
OF
MIXTURE Caked
Caked In order to determine whether the relative humidity had any Caked and sticky 2 Wet particular influence on the reaction and also t o obtain further data on the other product of the reaction, a second experiment was run in which five mixtures, each consisting of 1 gram of 100HUXIDITY ON CONIV. EFFECTOF VARYINGREL-~TIVE mesh urea and 1 gram of 100-mesh monocalcium phosphate TABLE AND TOTAL WATERCONTENT OF MIXTCRES GOSTAINING monohydrate, were kept at 30” C. for 3 months but each a t DITION &lOSOHYDR.4TE A S D UREA I S THE it different relative humidity. They were then washed into MONOC.4LCIUM PHOSPHATE MOLERATIO2 TO 1 flasks with 250 cc. of absolute alcohol, shaken 30 minutes on a k A T E R OF machine, and filtered through a dry filter. Aliquots were taken RELlTIVE CRYSTS. and evaporated t o dryness, the urea was destroyed, and PZOE LosT COXDITION or ~ I I X T U R E HUXIDITY was determined. Quantitative transfer from the dishes in which 70 % they mere exposed in the desiccators was difficult in the case of Badly caked 59.4 48.79 mixtures which had absorbed considerable moisture, and it is Badly caked 61.9 49.02 Badly caked 64.5 48.39 probable also that a small fraction of the urea phosphate failed t o Badly caked 67.56 47 .,a5 dissolve. Xeither of these errors, however, can have any effect Caked and slightly sticky 70. 1 Gained on the conclusions reached. The results are collected in Table 11. Badly caked 72.4 28.97=
%.
Developed a sticky condition the first week and, gained considerable
TABLE 11. EFFECT OF RELATIVEHUMIDITYON ALCOHOL- weight, but later dried out. SOLUBLE P20sIN MIXTURES OF UREAAND MONOCALCIUM PHOSPH.4TE RIONOHYDRATE To determine the hygroscopicity of a mixture that did not ALCOHOLbecome wet a t a relative humidity of 59.4 per cent, several WATERa SOL. COKDITION OF RELATIVE ABSORBED P20sb MIXTURE HUMIDITY mixtures were prepared, in which the mole ratio of monocal% Gram 70 cium phosphate monohydrate t o urea mas 2 to 1, and were 64.5 0.4624 42.4 Soln. present 61.9 0.2790 43.4 S o h . present stored a t various relative humidities. Table IV shows the 53.4 0 1676 42.6 Sticky condition of the mixtures after 30 days. All became caked 46.7 0,0897 43.6 Sticky OC -0.0617d 19.1 Caked and slightly sticky but the sticky condition did not develop under 70 per cent The figures are gains in weight. relative humidity. The action of the sample a t 72.4 per cent b Per cent of total PzOs present-namely, 0 5633 gram. c This sample was kept over PzOs. humidity is interesting. This sample gained considerable d Water lost. weight the first week and became sticky, but later lost all this If all the monocalcium phosphate had reacted with the urea, gain plus some additional weight and became badly caked. To determine the cause of the observed stickiness when which was present in excess, exactly 50 per cent of the PzO; should have become alcohol-soluble. The failure to obtain more than one mole of urea per mole of the mono- salt was complete conversion was probably due to the conditions of the present, a rough determination of the hygroscopicity of the experiment. I n any event, it is evident that no change in pairs urea phosphate-urea, urea phosphate-monocalcium conversion was accomplished by varying the relative humidity phosphate monohydrate, and urea phosphate-dicalcium 5
December, 1931
1N D U ST R I A L
A
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D E N-G I N E E R I N G C H E M I S T €1 k
a b o u t 'io p e r c e n t . It probably is liberated above that humidity also but r e m a i n s in the mixture as free water. Table V also shows that urea HUMIDITY ON COS- phosphate d o n e TABLEv. EFFECT O F V.4RYIiVG RELATIVE DITION AXD Loss OF U*ATER OF CRYSTALLIZATIOX FROM PAIRS does not cause URDA PHO~PHATE-MOSOCALCIUM PHOSPHATE MOSOHYDRATEm o n o c a l c i u m (.4) A S D UREA PHOSPH.ATE-DICALCIU>f PHOSPHATE phosphate monoDIHYDRATE (B) hydrate to part WATEROF with its water of RELATIVE CRYSTN. FINALCONDITION HUMIDITY LO ST^ crys tallization. A LI A B The small losses % % 70 shown were Slightly caked Good 90.49 59,4 0.84 Slightly caked Good 91.01 1.68 61.9 probably not due 64.5 Slightly caked Good b 86.24 27.6 Slightly caked Good b 85.95 to loss of water ,O.l Caked and slightly sticky Soln. present c Gained of Crystallization Weight lost considered water of crystallization lost. a t all but t o the b Gained less than 1% in weight of Ca(HzP04): Hz0 used. c Gained about 19Ybi n weight of Ca(HSPOd,,HzO used. evaporation of free moisture abThe hygroscopicity of the two triple mixtures urca phos- sorbed when the phate-monocalcium phosphate monohydrate-dicalcium phos- s a m p l e s w e r e phate dihydrate and urea phosphate-urea-dicalcium phos- mixed. The reaction phate dihydrate, the former representing the condition where excess monocalciuni phosphate monohydrate is present and of the urea with t,he latter where excess urea i q present, was also determined ni o n o c rtl c i u m approximately by the same procedure as above. Mixtures phosphate monocontaining an excess of monocalcium phosphate monohydrate hydrate is thereremained dry a t 72.4 per cent relative humidity while those f o r e t h e o n l y containing excess urea became wet a t approximately 60 per s o u r c e of f r e e cent relative humidity. Both types of mixtures, a t relative water in these humidities below that at which they tend to absorb water, m i x t u r e s , and lost weight corresponding quantitatively to the mater of crys- the amount of tallization of the dicalcium phosphate dihydrate present. such water liberThese results explain the experimental observation that ated from mixurea can be mixed with monocalcium phosphate monohydrate t u r e s of t h e up to a 1 to 1 mole ratio without producing stickiness. Since mono- s a l t and the hygroscopic pair is urea-urea phoqphate, it is evident that urea, where the the sticky condition should not arise if no excess of urea is former is in expresent except perhaps temporarily during the course of the cess, will be dereaction when both are present. Urea phosphate itself might termined solely be expected to be hygroscopic. The vapor pressure of its by the amount of saturated aqueous solution a t 30" C. was measured by the urea added. In authors, using the apparatus of Adams and Merz ( I ) , and actual fertilizer found to be 25.3 mm. of mercury, corresponding to a relative m i x t u r e s t h e humidity of 79.59 per cent; i t does not, therefore, tend to u r e a added take up water below this humidity. would, in general, The bad caking noted in Tables I11 and IV would not be insufficient to necessarily be serious in a mixed fertilizer where the presence r e a c t w i t h a l l of inert particles tends to prevent t h r interlocking of crystal the monocalcium lattices. phosphate .presTables 111 and IT shorn that, a t 30" C. and below 70 per ent. cent relative humidity, mixtures of monocalcium phosphate In order to see monohydrate and urea containing an excesj of 1 he former lose what this means, water of crystallization equivalent to the monocalcium phos- ajsume a mixture phate monohydrate required to react with all the urea pres- of u r e a a n d ent. Table V shows further that monoca!cium phosphate supe r p!i o s p ha t e monohydrate, in the presence of urea phosphate, gives up containing 3 per its water of crystallization almost completely and, in fact,, c e n t of t h e very rapidly since practically all this loss occurred the first former. In a ton week. This means that in the reaction between urea and (907.2 kg.) of monocalcium phosphate monohydrate the dicalciuin phos- such a mixture phate formed is anhydrous, and the water is liberated and there would be evolved from the mixture if the relative humidity is below l i b e r a t e d 18
phosphate dihydrate was made. It was found that mixtures of equal amounts of the pair urea phosphate-urea took up very little water a t 53.4 per cent relative humidity but became wet a t 59.4 per cent. The action of the other two pairs is shown in Table V. Both of the mixtures, except for slight caking in the case of urea plus monocalcium phosphate monohydrate retained their good condition up to about 70 per cent relative humidity. Mixtures of urea and dicalcium phosphate dihydrate, described later, show about the same result.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
pounds (8.2 kg.) of water amounting to 0.9 per cent of the total mixture. This small additional amount of free water should cause no trouble. Liberation of all the water of crystallization from the monocalcium phosphate monohydrate in a ton of superphosphate would increase the free moisture by only about 1.8 per cent.
Vol. 26, No. 12
forces as distinct from water of solution-is probably insignificant except perhaps a t the high humidities. A discussion of the effect of the humidity on the rate of loss is beyond the scope of the present paper except to suggest in passing that there appears to be an optimum humidity a t which the rate of loss of water of crystallization is a maximum. At 70.1 and 72.4 per cent relative humidity the mixtures UREAAND DICALCIUM PHOSPHATE DIHYDRATE fluctuate slightly in weight but show a small net gain. It The existence of the compound CaS04.4CO(KH2)2( 8 ) would appear that a t these humidities the tendency of the suggested a similar possibility in the case of urea and dical- hydrate to lose water is offset by the tendency of the urea to cium phosphate dihydrate. Accordingly, crystals of these dissolve in that water and retain it in the mixture. This two substances were placed in contact with a saturated aque- is evidenced by the fact that the dihydrate is still capable of ous solution of urea and kept a t 30” C. Occasional micro- losing water a t 75.2 and. 77.2 per cent relative humidities scopic examination failed to show any change in these solid (Table VI). Other samples of the dihydrate run at 79.2 per cent relative humidity and above showed no significant change in weight after 34 clays. This may mean that the end of the induction period had not been reached or that the vapor pressure of this hydrate corresponds to about 78 per cent relative humidity. The mixture is also shown by these results to have practirally the same hygroscopicity as urea itself, which tends to take up water a t relative humidities above 72.4 per cent (1) a t 30” C. X-ray diffraction patterns were made of the mixtures run at 59.4, 64.5, and 67.5 per cent relative humidities. There was no evidence of the presence of any compounds except anhydrous dicalcium phosphate and urea. This is in agreement with the failure to form a compound in the presence of a WATETEP M CPYSTALLIZAllON LOST- PERCENT solution phase. FIGURE 1. LOSS OF W A T E R OF CRYSTALLIZATION FROM UREAThe effect on hygroscopicity of varying proportions of the DICALCIUM PHOSPHATE DIHYDRATE MIXTURES (A) AND FROM two components of these mivtures was determined as folDICALCIUM PHOSPHATE DIHYDRATE ALONE ( B ) lows: Six miutures, all containing a total of 2 grams, were phases; that ia, no new solid phase appeared. After about 3 made up in which the proportions varied in regular steps from months a small amount of a mixture of solid urea and solid 1.8 grams of the dicalcium phosphate and 0.2 gram of urea to dicalcium phosphate dihydrate that had lost about 45 per 0.6 gram of dicalcium phosphate and 1.4 grams of urea. cent of its water of crystallization (discussed below) was added These mixtures were exposed 7 days to a relative humidity in a n attempt to “seed” the reaction. After a further period of 70.1 per cent, and their weight and condition were noted; of about 2 months, microscopic examination indicated that then they were exposed 7 days a t 72.4 per cent, and so on up the solid phases now consisted entirely of anhydrous dicalcium to 79.2 per rent in steps of about 2 per cent. All samples phosphate and urea. KO compound was formed under the remained practically constant in weight a t 70.1 per cent, conditions of this experiment, but the results indicate that the gained slightly when exposed a t 72.4 per cent, but showed large gains a t 75.2 per cent and, except for the sample constable solid phases in the system urea-dicalcium phosphatewater a t 30” C. are urea and anhydrous dicalcium phosphate. taining only 10 per cent urea, had all become slightly sticky. This conclusion is further substantiated by the experiments This sample retained its good condition up through 77.2 per cent relative humidity but became slightly sticky a t 79.2. on loss of water of crystallization from solid urea-dicalcium The others had all become very sticky or had developed phosphate dihydrate mixtures. Mixtures consisting of one gram each of finely ground urea visible solution phases. The results show that all dicalcium and finely ground dicalcium phosphate dihydrate were kept phosphate-urea mixtures are nearly as hygroscopic as urea at 30” C. a t various relative humidities for about 6 months. itself unless the proportion of urea present is very small. Ordinary superphosphates contain very little dicalcium One-gram samples of the dihydrate alone were stored under the same conditions but were started 2 months later. All phosphate, but on ammoniation the monocalcium phosphate samples were weighed every seventh day, except as noted in is more or less completely converted into the di- salt which Table VI, This table shows the percentage of the water of thus becomes an important constituent. Its state of hydracrystallization lost as calculated from the loss in weight of the tion is in doubt, but it would appear that the presence of urea sample. The data for the first fonr humidities, with some would render or keep it anhydrous. If relatively small amounts of urea are added to an ammoniated superphosphate, additional data not in the table, are plotted in Figure 1. If we consider the results a t 59.4, 61.9, 64.5, and 67.5 per the dicalcium phosphate present probably tends to render the cent relative humidity, it will be observed that in every case, mixture less hygroscopic. with the exception of the first 56 days at 64.5 per cent, the TR~CALCIUM PHOSPHATE AND UREA mixture lost water of crystallization much faster than the diThe action of tricalcium phosphate as a caking inhibitor in hydrate alone. All samples went through an “induction” period during which the rate of loss was very low. The salt and sugar has been described by MOPS,Schilb, and samples of dihydrate alone, except a t 64.5 per cent relative Warning (6). In this work mixtures of tricalcium phosphate humidity, showed a much longer induction period than the and urea were not studied under conditions where caking mixtures and at 70.1 per cent relative humidity actually would be expected, but it has been found that such mixtures gained slightly in weight during the early part of the run be- are in some cases much less hygroscopic than urea itself. cause of adsorbed moisture. The figures in Table V I are ac- Mixtures of urea and tricalcium phosphate in varying protual losses in weight and therefore represent water of crys- portions were stored a week a t 72.4 per cent relative humidity, tallization lost, minus more or less adsorbed moisture. This and their gain in weight and condition was noted; then they adsorbed water-that is, water held by surface or capillary were stored a week a t 75.2 per cent relative humidity, etc.,
December, 1934
I N D U ST R I A L A N D E N G IN E E R I N G C H E M I STR Y
until the samples became sticky. Very little caking was noted in any case, the mixtures remaining free-flowing until the sticky point was reached. S o loss of water of crystallization was noted in any case. The results are collected in Table VII. TABLE VII. HYGROSCOPICITY O F MIXTURES O F IJRE.4 WITH T W O SdMPLES O F TRICALCIUM PHOSPHATE ( A , B ) A S D WITH ANHYDROUS TRICALCIUM PHOSPHATE (C) PHOSPHATE IN
MIXTURE
% 90 80 60 50 40 30
RELATIVEHUMIDITY WHEN MIXTURE BECAME STICKY % A B C 96:3 77.2 77.2 77 2 77.2
96.3 85.2 75.2 75.2 75.2 75.2
96.3 85.2 77.2 77.2 77.2 77.2
TOTAL GAINIK W E I G H T WHEN MIXTUREBECAME STICKY
urea and hydrated tricalcium phosphate do not lose water of crystallization under any of the conditions tried is partial evidence that no compound exists.
ACKNOWLEDGMENT The writers wish to thank S. B. Hendricks and M. E. Jefferson for making the microscopic and x-ray determinations. Thanks are due also to various members of the staff for valuable suggestions and the loan of analyzed materials.
% A 75 89 27 28 24 26
B
C
52 29 24 22 19 16
55 33 19 18 13 12
When the proportion of tricalcium phosphate is below 80 per cent, all mixtures become sticky a t a relative humidity slightly above that a t which urea itself becomes sticky (72.4 per cent), but, when more than 80 per cent tricalcium phoqphate is present, the mixture is very nonhygroscopic and is able to withstand relative humiditieq of 85 per cent or higher. No attempt has been made to prepare a compound between urea and tricalciurn phosphate. The fact that mixtures of
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LITERATURE CITED Adams and Mera, IND.ENG.CHmf., 21, 305 (1929). Assoc. Official Agr. Chem., Methods of Analysis, p. 16 (1925). 4 Ibid., p. 20. Clark, J . Phys. Chem., 35, 1232 (1931). Keenan, ISD. ENG.CHEM.,22, 1378 (1930). Matignon, Dode, and Langlade, Compt. rend., 194, 1289 (1932). Mom, Schilb, and Warning, IND.ESG. CHEM.,25, 142 (1933). (7) Ross, Jacob, and Beeson, J . Assoc. Oficial *4gr. Chem., 15, 227 (1) (2) (2 (3) (4) (5) (6)
(1932). (8) Whittaker, Lundstrom, and Hendricks, IXD.ENG. CHEV.,25, 1280 (1933). (9) Wiley, “Principles and Practice of Agricultural Analysis,” p. 162, Chemical Publishing Co., Easton, Pa., 1931.
RECEIVED September 22, 1934.
Effect of Malvaceous Seeds on Stored-Egg Quality F. W. LORENZAKD H. J . ALMQUIST, University of California, Berkeley, Calif.
A
T Y P E of deterioration Crude kapok oil, the seeds of cheeseweed of yolk deterloration similar t o of the the effects of cottonseed oil. in stored eggs, known in (buttonwuredor mallow) and other t h e trade as “pink Schaible, Moore, and RIoore (’7) family .I falcaceae, as well a s cottonseed meal after feeding cottonseed meal, white>,” has caused occasional severe l o s s e s . Characteristic and crude Or Partially refined cottonseed oil, crude or treated in a number of ways, have concluded that yolk symptoms of this form of decause the “pink-white” storage deterioration in discoloration is due to gossypol, terioration are: eggs. The inclusion of these materials in the feed of whicht”aspresentin thoseprod(a) The albumen 19 ucts found to discolor yolks. t o reddish in color but normal in laying h m s can be detected by applying the Sher.il.ood (9) has reported other respects. Halphen test to the feed and to the yolk f a t Of chemical analyses of yolks from ( b ) The yolk color varies from normal t o a salmon or near red. fresh or stored eggs produced by these hens. hens fed cottonseed meal and (c) The yolks are noticeably has pointed out that not only Cheeseweed is common in m a n y poultry dislarger than normal. water but protein may be ( d ) The yolkmaterialiswatery tricts, and is more often available to poultry taken up by the yolks during at room temperatures but usually than Other members Of Ihe plant family* cold storage. claylike in consistency at cold storage temperatures. This weed is probably ihe primary cause of pink EXPERIRIEKTS TO CORRELATE ( e ) The cooked yolks are rubwhites where cottonseed meal is not fed. bery in consistency PINK-WHITE DEVELOPMEKT ( j ) The yolks tend to acquire WITH FEEDING a normal color, rind the pink tinge of the albumen tends to disappear when the eggs are cooked. In the supply of pink-white eggs submitted to this labora( 9 ) Bacteriological examination shows that pink-white eggs tory, several normal eggs were found which had received the may be free from d&ructive microorganisms. same storage treatment as the others, hence it waq possible ( h ) The eggs have no abnormal odor. to make a comparison of the chemical analyses of yolks from This list includes many of the effects of cottonseed meal the two kinds of eggs. Composite samples of yolk from the feeding, as described by Sherwood (8,g), Sipe ( I o ) , Thomp- two sources were dried to practically constant meight. The son ( 1 1 ) and ~ KemPster (6). The whites are often Pink and crude fat was determined by thorough extraction with ethyl the Yolk color may often be red, olive, brown, Or black. The alcohol, and the crude protein was determined by the usual loss of quality in storage eggs appears to increase with the Kjeldahl procedure, The results are as follows: cottonseed meal content of the ration. Except when large CRUDE CRUDE amounts of cottonseed meal have been fed, the fresh eggs FAT PROTEIN PROTEIN appear to be normal. TOTAL ( O N DRY (Ov DRY FAT Heller, Searcy, and Thompson ( 3 ) have reported that S O U R c E O F yoLK BASIS) BASIS) RATIO % % % gossypol, present in cottonseed oil, does not discolor egg Normal stored eggs 68.4 31 9 0 47 47.8 yolks when fed in a purified form but does cause other forms Pink-white eggs 39.7 63.3 36.5 0.58
