9 * 
CONTENTS. 
PAGE. 
The available'phosphoric acid in fish scrap, tankage, azotin, dried blood, bone 
meal, and cotton-seed meal... 3 
Estimation of available phosphoric acid. 3 
Effect of fineness upon available phosphoric acid. 3 
Methods used in determining phosphoric acid in organic materials. 4 
For total phosphoric acid. 4 
With nitric and hydrochloric acid. 4 
Ignition with magnesium nitrate. 4 
For soluble phosphoric acid. 4 
By direct precipitation. 4 
Evaporation, ignition, and solution in nitric and hydrochloric acids.. 4 
For insoluble phosphoric acid. 4 
Regular official method. 4 
By direct solution of filter and residue in nitric and hydrochloric acids 4 
Conclusions in regard to methods. ... 4 
Results of analyses.-. 6 
Effect of washing the magnesium-ammoninum-phosphate precipitate upon 
the percentage of P 3 0 5 . 8 
Total and water-soluble potash in cotton-seed meal. 9 
Some forms of apparatus in use in the N. C. Experiment Station laboratory.. 10 
Hydrogen generator and hydrogen bath. 10 
Insoluble phosphoric-acid bath. 12 
