ELISHA MITCHELL SCIENTIFIC SOCIETY. 55 



(Report Phos. Acid Committee, Cbem. Bui. U. S. Dept. Agr. No. 7, 

 p. 11.) 



To ascertain the time required for complete expulsion of moisture, 

 such as is driven off at a constant temperature of 100*^C, I have in- 

 stituted a set ef experiments, using both acid phosphates and am- 

 moniated guanos for the comparison and heating for different inter- 

 vals. The portions were of two grammes each, carefully weighed 

 in watch glasses, heated in steam bath, taken out and cooled in 

 well-fitting dessicators, weighed, returned to bath, taken out, re- 

 weighed, &c. The heating was interrupted but I am satisfied the 

 result was not seriously affected, as the time consumed in drying 

 and weighing was short. The steam bath registered a constant tem- 

 perature of a fraction less than 100°C, never more- than 100°C, so 

 that the possibility of the oxidation of organic matter was lessened. 

 The actual percentages of moisture found are given in Table I. A 

 and C are acid phosphates, B, D and E are ammoniates: 



