262 § 135. FODDER AND FOOD. 



gypsum, dry it at 100-105° C, and ignite the residue 

 with soda-lime (§ 85). 



d. Starch. — Determine this, together with a small quan- 

 tity of gum, in 2.5-4 grms. of dry substance (§ 79). 



For technical purposes, it is often sufficient to determine 

 the specific gravity of the potato, in order to estimate ap- 

 l^roximately the goodness of the tuber, or the amount of 

 dry substance and starch that it contains. 



Determine the specific gravity as directed in § 35, e. 

 The temperature of the saline solution should be about 

 16° C. The relation between the specific gravity and the 

 amount of dry substance and starch is given in Table VII. 

 Potatoes that have been afiTected by disease cannot be 

 examined in this way unless the diseased parts are cut out. 



Artichokes may be examined in the same way as 

 potatoes, except that the aqueous extract of the former 

 should be more carefully examined for glucose. The 

 inuliu in the artichoke is converted into glucose somewhat 

 more easily than the starch in potatoes. 



SEEDS. MEAL. FLOUR. 



135i Seeds are crushed in a mortar or ground to a fine 

 powder in the steel mill. 



a. Water. — Desiccate 5-10 grms. of the powder, and 

 preserve the rest in well-stoppered bottles. 



1). Non-volatile matter, protein compounds, fat, crude 

 cellulose. — Estimate these precisely as directed for the 

 examination of fodder (§ 129, c^ § 130, 5, o, d), 



c. Dry suhstance soluble in water.— Determine this 

 as directed in § 134, ^, with 20 grms. of the powder. 



d. Starch. — Follow any of the methods described in 

 § ^9. 



Or, wash 2 grms. of the powder on a filter, first with 

 cold water, then with alcohol containing sulphuric acid, 



