6 BULLETIN 1179, U. S. DEPARTMENT OF AGRICULTURE. 
A REVIEW OF METHODS FOR PRODUCING PHOSPHORUS AND 
PHOSPHORIC ACID BY VOLATILIZATION. 
While the production of phosphorus has always depended on the 
volatilization of this element from its compounds under reducing 
conditions, in the early days of its manufacture the system employed 
was elaborate, cumbersome, and costly. 11 It involved, first, the 
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32700 Lbs P x 5 \r\ car loaded. 
/ wi+h lipoid Phosphoric Actd. 
Fig. 4.— A car loaded to capacity (60,000 pounds) with liquid phosphoric acid (75% H 3 PO0 manufac- I 
tured by the pyrolytic or furnace process contains 32.700 pounds of actual P2O5, or nearly three and 
one-half times as much as that in a car of acid phosphate. 
treatment of phosphate of lime with sulphuric acid; second, the 
separation by filtration of the phosphoric acid thus obtained: third, 
the concentration of this acid by evaporation: and. fourth, the mixing 
of this acid with charcoal or coke and the heating of the mixture to j; 
high temperatures in clay retorts. Practically every step entailed \ 
Fig. 5.— A car loaded to capacity (60,000 pounds) with either double acid phosphate or mono-ammonium 
phosphate contains from 28,800 to 37,000 pounds of actual P 2 0.,, or from three to four times as much 
as that in a car of acid phosphate. By shipping our phosphoric acid (P2O5) in these concentrated 
forms an annual saving of from $8,000,000 to 89, 000,000 in freight charges alone might be eventually 
effected on this fertilizer ingredient. 
some loss of the material sought, so the recovery of the phosphorus 
was very incomplete. 
Apparently the substitution of silica for sulphuric acid, so tEat 
phosphorus could be produced directly from phosphates of lime, was 
first proposed by Auberton and Boblique 12 in 1867, when these 
inventors took out a patent for volatilizing and collecting elementary 
"Readman, J. B. 
12 Readman, J. B. 
An account of the Manufacture of Phosphorus. 
J. Soc. Chem. Ind. 9, p. 473 (1890). 
J. Soc. Chem. Ind. 9, p. 163(1890). 
