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4 it can be seen that the dicalcium phosphate disappears more to leach away this precipitated material from the rock phosrapidly than the monoammonium phosphate. Up to 4 or 4.5 phate by properly adjusting the relationship between sample per cent NH3 the temperature during ammoniation is between size and volume of citrate. Field and pot tests are now being 70" and 90" C., and the first major reaction is apparently 2CaHP04 CaS04.2HzO 2NH3 + conducted by the U. S. Department of Agriculture and several CadP04)~ (NH4)2SO4 2H20 ( 2 ) state experiment stations on the fertilizer value of these resiAs this progresses and more ammonia is absorbed the temperature gradually rises and a t the higher temperatures (90" to 100" C.) dues from ammoniated superphosphate. Thus, in conclusion, it can be said that ammonia absorption the monoammonium phosphate reaction is accelerated. By the time the dicalcium phosphate has all reacted, the reaction pro- by superphosphate follows three or four separate major ceeds as: reactions. Temperature and moisture are apparently the NH4HZP04 CaS04.2HzO NHI + controlling factors in determining the extent and rate a t (hTH4)zSO4 CaHPO4 2H20 (3) The dicalcium phosphate so formed may subsequently react as which each of these three occurs. However, the direct ab(2), but from an analytical study of the precipitated phosphate sorption of anhydrous ammonia under present works condimaterial it apparently remains largely as dicalcium phosphate tions up to 1 mol NH3 per mol water-soluble Pz06(approxiintimately mixed with more basic phosphate compounds. The fact that monoammonium phosphate gradually decreases as mately 2 per cent NH3) does not decrease the availability the ammonia absorbed is increased above 1 mol NH3 per mol of the PZO5 as determined by present analytical methods. water-soluble P205 indicates that (3) occurs simultaneously with More than 1 mol h'H3 per mol water-soluble does decrease (2). the available P2O6. This decrease may be slow if the am(3) Under controlled conditions, low temperature and mois- monia is introduced under controlled conditions, or it may be ture content, it is possible to direct the reactions as follows: within a few hours if the ammonia is introduced in the direct CaH4(PO& 2NH3 +CaHP04 (NH&HPO4 Consequently, Reaction 2 above does not occur until after 2 and most economical way. The physical condition of mols of NH3 per mol water-soluble P205 have been introduced, or ammoniated superphosphate is markedly superior to superthe temperature rises. Superphosphate ammoniated under such conditions is not an equilibrium mixture and slow reversion may phosphate, and since the ammoniated material is of different composition than unammoniated superphosphate, the reoccur.
+
+
+
+
+
+
+
+
+
+
actions when mixed with other ingredients to complete fertilizers result in much less tendency to setting or caking.
Conclusion
It is beyond the scope of the present paper to give detailed results from the analytical study of this precipitated calcium phosphate material. It can be said, however, that the Pz06precipitated by ammonia from such material as superphosphate exists as a mixture of several calcium phosphates, largely tricalcium phosphate, but also dicalcium and some even more basic compounds than the tricalcium salt are present. This mixture is approximately half as soluble in neutral citrate solutions as is dicalcium phosphate, and many times more soluble than natural rock phosphate. The CaO:Pz06ratio in the residue from neutral citrate extraction of ammoniated super (2 grams per 100 cc. citrate) is between 1.0 and 1.4. If the volume of citrate is iacreabed or sample she decreased, this ratio increases and approaches that found in rock phosphate, 1.5 to 2.0. Hence it is possible
L i t e r a t u r e Cited (1) Andreasen and Raaschou, Danish Patent 33,605 (1924) (2) Andreasen and Raaschou, Nordisk. Jordbriig, 5-6, 285-(1923). (3) Bassett. Z . anori. Chem . 63. . 49 (1907). . Besemfelder, German Patent 117,795 (1901). Bolton, U. S. Patent 248,632 (1881). Brioux, Compt. rend. acad. agr. France, 4, 632 (1914). Gerlach, German Patent 282,915 11916). Gerlach, 2. angew. Chem., 29 (11, 13 (1916). Gerlach, I b i d . , 29 ( l ) , 18 (1916). Grahn, German Patent 47,601 (1889). Hagens, U. S. Patent 1,699,393 (1929). Matignon, Chimie et industrie, 10, 217 (1923). McDougall, U. S. Patent 135,995 (1873). St. Gobain, French Patent 570,266 (1924). Willson and Haff, U. S. Patents 1,040,081, 1,062,869, 1,112,183, 1,122,183, 1,127,840, 1,145,107, 1,146,222, 1,161,473, 1,166,104.
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Viscosity Data in Graphical Form' R a y m o n d P. Genereaux EXPERIMENTAL STATION, E. I .
DU
PONTDE NEMOURS & COMPAXY, WILMIKGTON, DEL
HE viscosity factor enters into many calculations used in chemical engineering research, design, and operation. The wide variety of fluids encountered in practice often necessitates a search for viscosity data which are scattered in tables, handbooks, and journal articles. The data are often in units not readily applicable to the formulas, requiring conversion to some consistent set of units. For example, the data on aqueous solutions of strong electrolytes in International Critical Tables, Vol. V, p. 12, are given in terms of relative viscosity, the viscosity of the solution being referred to the viscosity of water, both a t the same temperature. I n other sources values are found as seconds on the Redwood, Engler, or Saybolt viscometer. Other units used are kinematic viscosity relative to specific gravity or to density. C. g. s. units are often found, but involve a factor of 10". Confusion and error are certain
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1 Received September 8, 1930. Contribution No. 44 from the Experimental Station, E. I. Du Pont de Nemours & Company.
with such diverse units. With a view to correlating the available data and simplifying the presentation, the accompanying charts were constructed. The method of plotting used is that suggested by Ravenscroft (8). The centipoise was chosen as the unit for expressing viscosity values. The poise is the c. g. s. unit of viscosity; the centipoise is 0.01 poise. The viscosity of any fluid in centipoises is numerically equal to the viscosity relative to water a t 20" C. Use of the centipoise requires no more than two or three ciphers after the decimal point and avoids the confusion encountered in using powers of ten. An exhaustive search was made for data on each fluid represented on the charts. The appended bibliography includes some of the sources of data. Values were plotted on log-log paper with viscosity in centipoises us. the absolute temperature. This is the method as used by Herschel (3) and, as with his data on oils, the points for most of the fluids on these charts fell along a straight line. For those few
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ILVDUS T R I AL A AVD E-VGINEERING CHEIIlIS T R Y
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LIQUID VISCOSITIES
1
1
VISCOSITY IN CENTIPOISES
TEMPERATURE
I8
ACETIC ACID
I2
ACETK K I D 70% ACETONE ALLYL ALCOHOL AMMONIA ANILINE BENZOL BUTYL ALCOHOL CARBON DiOXlDE C M B O N OlWCFlDE CARBON TETRACHLWIOE CHLORBENZENE CHLM)OFORM ETHER ETHYL ALCOHOL 100% ETHYL ALCOHOL 40.6 ETHYL ACETATE CTHYLENL CHLORIDE ETHVLENE GLYCOL
24 17
38 8
25
ldo
300
30
23
1007.
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GLYCERIN
50.h
HEPTANE HEXANE ( N I MERCURY METHYL ALCOHOL 100%
11 I
1 27
20
6
OCTANE PENTANE PHENOL SULFUR DIOXIDE SULFURIC K I D I l l % SULFURIC ACID 98% SULFURIC ACID 6om TOLUOL TURPENTINE WATER
8 8
l2
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INDUSTRIAL A N D ENGILVEERING CHEMISTRY
fluids which deviated the nearest straight line was drawn, the error in no case exceeding 10 per cent and then only in the extremes of temperature. For the gas-viscosity chart (Figure 1),two logarithmically scaled lines of temperature and viscosity were placed close and parallel to each other. The temperature line was scaled in degrees Kelvin, but marked off in corresponding degrees Centigrade and Fahrenheit. Points on the chart were located RS follows: Temperature and viscosity values were taken for two points from the straight line chosen t o represent the variation of viscosity with temperature for each gas. Lines were then drawn through the corresponding values on the temperature and viscosity scales of the chart. The intersection of these lines determined a point characteristic of the fluid. A line from a point on the chart, drawn through a temperature value, will cross the viscosity line a t the value for that temperature. Fourteen gases and two mixtures are given. For liquids (Figure 2), the same procedure was followed, but in this case the points fell between the viscosity and temperature scales because liquids decrease in viscosity with rise in temperature. Forty liquids are given.
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All data are for atmospheric pressure. The viscosity of gases is theoretically independent of pressure, and for moderate ranges of pressure this is true. For “permanent” gases the atmospheric pressure values can probably be used t o 100 atmospheres without appreciable error. For liquids such as water the atmospheric pressure values can be used up to about 500 atmospheres. iidditions to either chart may easily be made by following the method outlined, provided data are available for the fluid in question. L i t e r a t u r e Cited a n d Bibliography for Viscosity D a t a (1) Bingham and Jackson, Bur. Standards, Sci. Paper 298, 73 (1917). (2) Cocks, J . SOC.C k m . I d . , 48, 279T (1929). (3) Herschel, Oil Gas J . , 25,135 (1926); J. IND. E m . CHEM.,14,715 (1922). ( 4 ) International Critical Tables, Vol. V. (5) Kaye and Laby, Physical and Chemical Constants, 1918. (6) Landolt-Bornstein Tabellen, 1923, 5. A d a g e , Band I ; 1937, 5. A d a g e , Erster Erganzungsband mit Generalregister. (7) Martin, “Treatise on Chemical Engineering,” 1928. (8) Ravenscroft, IND. ENG. CHEW, 21, 1203 (1929). (9) Rhodes and Barbour, IND. ENG.CHEM.,15, 850 (1923). (10) Smithsonian Tables, 1920.
ComDosition of Citrate-Insoluble Residues from Superphosphates and Ammoniated Superphosphates’ A
K. D. Jacob, W. L. Hill, W. H. Ross, a n d L. F. Rader, Jr. FERTILIZER A N D FIXED NITROGEN INVESTIGATIONS, BUREAU OP CHEMISTRY A N D SOILS,WASH:XGTON, D. C.
UPERPHOSPHATES always contain a small quantity of phosphoric acid that is insoluble in neutral ammonium citrate solution according to the official method of analysis (1). So far as the writers know, the nature of this citrate-insoluble phosphoric acid has never been thoroughly investigated, but it seems to be the general opinion that it is present principally as undecomposed phosphate rock. When superphosphates are treated with relatively large quantities of ammonia, the percentage of citrate-insoluble phosphoric acid increases to a degree approximately dependent upon the quantity of ammonia added. I n this case it is known that a large portion of the citrate-insoluble phosphoric acid is combined as calcium phosphates, particularly tricalcium phosphate, but it is not known whether the iron, aluminum, and fluorine compounds always present in commercial superphosphate play an important part in the formation of citrate-insoluble phosphoric acid. The present paper gives the results of a study of thecomposition of the citrate-insoluble residues obtained from eleven samples of superphosphates and ammoniated superphosphates.
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P h o s p h a t e Materials Used
Florida Pebble Superphosphate, No. 1037. This was a well cured commercial material manufactured in the usual manner. Ammoniated Florida Pebble Superphosphate, No. 1036. This material, which contained 5.76 per cent ammonia, was prepared experimentally on a semi-commercial scale from the same batch of superphosphate from which sample No. 1037 was obtained. Florida Pebble Superphosphate, No. 1060. This material, which is sold under the trade name of “Oberphos,” was prepared commercially by a special patented process. Ammoniated Florida Pebble Superphosphate, 17-0. 1050. This 1 Received September 22, 1930. Presented a s a part of the symposium on “Action of Ammonium Citrate on Superphosphates” before the Division of Fertilizer Chemistry a t t h e 80th Meeting of the American Chemical Society, Cincinnati, Ohio, September S to 12, 1930.
material, which contained 4.97 per cent ammonia, was prepared experimentally from the same batch of superphosphate from which sample No. 1060 was obtained. Florida Pebble “Den” Superphosphate, N o . 1073. This material was obtained by artificially drying freshly manufactured commercial superphosphate in order to prevent further conversion of citrate-insoluble phosphoric acid into soluble forms. Tennessee Brown-Rock Superphosphate, No. 1066. This was a well cured commercial material manufactured in the usual rnanner. Ammoniated Tennessee Brown-Rock Superphosphate, No. 1067. This material, which contained 4.35 per cent ammonia, was prepared experimentally from the same batch of superphosphate from which sample No. 1066 was obtained. Tennessee Brown-Rock “Den” Superphosphate, No. 1087. This material was obtained by artificially drying freshly manufactured commercial superphosphate. Tennessee Brown-Rock Triple Superphosphate, No. 1059. This material was manufactured several years ago and probably differs somewhat in its composition and properties from the same type of material manufactured a t present. Ammoniated Tennessee Brown-Rock Triple Superphosphate, X o . 1039. This material, which contained 7.51 per cent ammonia, was prepared experimentally from recently manufactured triple superphosphate. Idaho Triple Superphosphate, N o . 1061. This was a recently manufactured commercial product. M e t h o d of Determining Citrate-Insoluble Phosphoric Acid
When tricalcium phosphate and highly ammoniated superphosphates are treated with neutral ammonium citrate solution according to the official method, clear filtrates cannot be obtained because a portion of the phosphate goes into the colloidal condition and passes through the filter paper, thus resulting in low values for citrate-insoluble phosphoric acid. Clear filtrates from such materials were obtained, however, by the use of short Pasteur-Chamberland filter tubes (grade F). Duplicate results were in excellent agreement and, in the case of phosphates which filtered clear through paper, the method gave results that checked closely
