66 



and accurately weighed in a previously weighed and covered plati- 

 num dish. They are carefully spread out by means of a spatule, 

 which after use must always be cleaned by means of a small brush. 

 They are then dried in an air bath at from 100 to 110° C, under 

 frequent stirring. The dish and cover are placed in a dessicator 

 to cool, and then weighed. This must be repeated until the weight 

 remains constant. 



Determination of the Ash and Phosphoric 



Acid. 



The combustion for the determination of the ash must be carried 

 out at as low a temperature as possible, so that none of the more 

 volatile constituents of the ash are lost by volatilization. It is best 

 to operate as follows : The whole is heated to complete carboniza- 

 tion of the contents, which are then transferred to a porcelain dish 

 and extracted with water. The solution is then filtered off. The 

 filter and the residue upon it are then again transferred to the 

 platinum dish and, after drying, incinerated. The water solution, 

 unless it be preferred to determine it separately, is then, together 

 with the ashes, evaporated to dryness, then heated to a dull red 

 heat, and allowed to cool in a dessicator. It is then weighed. 



The determination of the phosphoric acid is carried out after 

 the manner described on page 23. 



Determination of Fat. 



Some of the milk-food from the center of the box is placed 

 into a dry stoppered test tube, which is weighed. From 2 to 

 3 grms. are then brought upon a dry filter resting in a small fun- 

 nel. The tube is then re-weighed, the difference being equal to 

 the quantity placed upon the filter. The funnel, with contents, is 

 then dried in an air bath, at from 80 to 100° C, for a short time, 

 to remove the bulk of the moisture. Filter and substance are then 

 transferred from the funnel to the funnel belonging to the appa- 

 ratus described by the author for the determination of the fat. 

 This funnel is then adjusted to the weighed flask, and ether, free 

 from alcohol, is poured upon the filter, care being taken that none 

 of the food is carried over the edges of the filter. When the flask 

 is about half filled with ether, the apparatus is connected, and the 



