INVESTIGATIONS UPON THE PHOSPHORIC ACID IN CRUDE 
FERTILIZER MATERIALS AND UPON METHODS 
OF FERTILIZER ANALYSES. 
I. ON THE AVAILABLE PHOSPHORIC ACID IN FISH SCRAP, TANKAGE, 
AZOTIN, DRIED BLOOD, BONE MEAL, AND COTTON-SEED MEAL, 
AND THE METHODS USED IN ITS DETERMINATION. 
By B. W. KILGORE and R. E. NOBLE, Assistant Chemists. 
The following investigations were made with a three-fold object— 
1. The estimation of the available phosphoric acid in the several 
fertilizer materials. 
2. The effect of fineness upon the available phosphoric acid in 
them. 
3. The methods to- be used in determining total, soluble, and 
insoluble phosphoric acid in these materials. 
1. Available Phosphoric Acid .—Fish scrap, bone meal, and cotton¬ 
seed meal are sold quite largely in this State, both alone and in 
mixed goods, and all the other fertilizer materials are sold to a greater 
or less extent in mixed fertilizers. No claim is made for available 
phosphoric acid in any of them when on sale as such, but in mixed 
goods their available phosphoric acid, of course, appears along with 
that of the acid phosphate, or other phosphoric-acid-yielding mate¬ 
rial. This Station has heretofore estimated 2.5 per cent., 4 per cent, 
and 3 per cent, for the amount of available phosphoric acid in cot¬ 
ton-seed meal, tankage, and fish scrap respectively. The results of 
the analyses here reported confirm the practical correctness of this 
assumption, as will be seen by reference to the table, though tank¬ 
age is subject to very wide variations in this respect. Our average 
results show the available phosphoric acid to be, in fish scrap 3.08 
pe*: cent, tankage 5.17 per cent., beef azotin 2.54 per cent., pork 
azotin 1 00 per cent., dried blood .71 per cent., bone meal 6.01 per 
cent, and cotton-seed meal 2.65 per cent. 
2. Fineness .—The factor of fineness appears to have had little or no 
influence on the amount of phosphoric acid dissolved by cold distilled 
water and “ammonium citrate solution” (the available phosphoric 
acid), except in the case of bone meal, where there is an average differ¬ 
ence of .51 per cent, in favor of the samples put through the 40-mesh 
seive, which is approximately 40 meshes to the linear inch. The 
average results of all the others, except beef azotin, where they are the 
same, are slightly higher for the 40 than the 20-mesh seive, but the 
differences are rather too small to be taken into consideration. Cot- 
