1895.] 



PUBLIC DOCUMENT — No. 33. 



307 



was diluted with 25 cubic centimeters of water, appearing 

 then as a thick, black fluid. To this fluid were added 60 

 grams of floats. The resulting superphosphate, after drying 

 in the air for twenty-four hours, weighed 102 grams. The 

 tannic acid reaction was quite strong. 



Experiment IV. — To 30 grams of 50° B. acid were added 

 25 cubic centimeters of water and 70 grams of floats. The 

 dry superphosphate weighed 101.5 grams. 



Experiment V. — To 30 grams of 50° B. acid were added 

 9 grams of Philadelphia tankage, which resulted in a medium 

 thick paste. Twenty cu1)ic centimeters of water and 48.5 

 grams of floats were afterwards added. The dry superphos- 

 phate weighed 88 grams, and gave no tannic acid reaction. 



Experiment VI. — To 30 grams of 40° B. acid 9 grams 

 of Philadelphia tankage were added, resulting in a medium 

 thick paste. This paste was diluted with 20 cubic centi- 

 meters of water, and 50 grams of floats were put in. 

 Seventy-nine grams of superphosphate were obtained, which 

 gave a strong tannic acid reaction. 



These several products were analyzed : — 



nr. 



I'lii- Cent. 



IV. 

 Per Cent. 



V. 



Per Cent. 



vr. 



Per Cent. 



Moisture, 



Soluble phosphoric acid, 

 Reverted j)hosphoric acid. 

 Insoluble phosphoric acid, . 

 Total phosi^horic acid, . 

 Total nitrogen, .... 

 Nitrogen after artificial digestion. 

 Per cent, of total nitrogen digested. 

 Soluble nitrogen, .... 



14.14 



6.78 



1.22 



5.50 



13.50 



.81 



.37 



54.00 



trace 



14.13 



7.30 



1.60 



6.66 



15.56 



14.86 



7.80 



.44 



4.94 



13.18 



.87 



.25 



71.00 



trace 



1.03 



.41 



60.00 



It would appear that 9 grams of leather were all that 

 could be added to 30 grams of sulphuric acid without getting 

 the tannic-acid reaction. When, as in Experiment III., 12 

 grams of leather were added, the reaction for tannic acid was 

 quite marked, and the nitrogen in the superphosphate had a 

 digestibility of 1)ut 54 per cent. Experiment VI. indicates 

 that 40° B. sulphuric acid was not quite strong enough to 



