59 



digestion flasks used in nitrogen estimations. A small quantity of hydro- 

 chloric acidt was also used to hasten the liberation of oxygen from the 

 nitric acid. As the nitric acid became exhausted more was added from time 

 to time. After about one hour's digestion solution was usually effected and 

 nothing but the elaidin formed from the fats was left. This latter was 

 easily filtered off and then the solutions were made up to a volume of 

 250 cc. with water. 



Determinations. 



Calcium : Aliquot parts of the solution were used, and the calcium 

 precipitated with ammonium oxalate and determined in the usual way. 



Phosphoric acid (P2O5) : Aliquot parts were used from which the 

 hydrochloric acid was expelled by repeated evaporation with nitric acid. 

 The phosphoric acid was then determined volumetrically, as outlined in 

 Methods of Analysis under Optional Volumetric Method, p. 13. 



Calcium in the Chick : The contents of the egg (the chick) after incu- 

 bation were not examined for phosphorus and the method of extracting 

 the calcium was changed for one which was not quite so exacting on time 

 and material. The shell and membrane were completely removed and 

 discarded. 



Method of Making Solution : The chick was placed in a porcelain 

 dish and incinerated more or less completely. Complete carbonization is 

 as far as the process need be carried, for at that stage all mineral constitu- 

 ents are freed from their organic combinations. After combustion the 

 contents of the dish were pulverized and extracted with successive portions 

 of strong hydrochloric acid until exhaustion was complete. The different 

 extracts were then combined and made up to a volume of 250 cc. with 

 water. 



Determination: Aliquot portions of the solution were pipetted off, 

 treated with a small quantity of ferric chloride to remove phosphoric acid, 

 neutralized with ammonia and the ferric phosphate and ferric hydrate 

 filtered off and washed. Calcium was precipitated from the combined 

 filtrate and washings with ammonium oxalate and estimated in the usual 

 way. 



The results obtained are as follows : 



^Methods of A.O.A.C., A under total phosphoric acid in fertilizers, p. 12. 



