SPECIFIC GRAVITY OF V/HEAT AND OTHER CEREALS. 



HOW TO MAKE THE SPECIFIC- 

 GRAVITY TEST. 



In addition to the picnometer, or 

 specific-gravity bottle, used in making 

 the determinations, it is necessary to 

 have a good analytical balance and an 

 aspirator, or filter pump. If it is de- 

 sired to purify the toluene used in pre- 

 vious tests, gas burners or some other 

 form of heating appliance and conden- 

 sers will be required in addition to the 

 apparatus mentioned. 



After the capacity of the picnometer 

 has been ascertained by weighing it 

 when empty and likewise when filled 

 with distnied water at 20° C, the speci- 

 fic gravity of the toluene is determined 

 in the usual way by comparing the 

 weight of toluene which the bottle holds 

 with the weight of the distilled water 

 at the same temperature: 



Weight of water : weight of toluene :: 1.0000 



:x, 



Fig. 1. — Picnometer used in specific-gravity 

 detenni nations. 

 [Qir. 991 



X equaling the specific gravity of the 

 toluene. Each lot of toluene must be 

 tested, as there may be a slight vari- 

 ation in its specific gravity. 



Ten grams of the cleaned wheat 

 sample (the exact weight being re- 

 corded) are placed in the picnometer, 

 and a sufficient quantity of cooled tolu- 

 ene is added to a little more than cover 

 the wheat. The cap is placed on the 

 capillar}^ tube, the neck of the picnom- 

 eter connected with the filter pump, or 

 aspirator, and the air gradually ex- 

 hausted. Tliis promotes the escape of 

 the air from the mass and particularly 

 that held under the surface hairs and 

 in the creases of the kernels. Wlien 

 the air bubbles cease to be given off, the 

 vacuum is released for a moment and 

 the bottle is then reexhausted. When 

 no more bubbles rise, the picnometer is 



