no 



AGRICULTURAL CHEMISTRY 



carbons, often accompanied with gaseous hydrocarbons. 



The hydrocarbons distilled off at a low temperature, rang- 

 ing from 8 to 68 C., form 

 the gasoline and benzine prod- 

 ucts, while those which distil 

 between 175 and 215 C. form 

 the various grades of kerosene. 

 In the preparation of gasoline, 

 benzine, and kerosene, the sep- 

 aration of the various grades 

 of hydrocarbons is not com- 

 plete ; kerosene, for example, 

 may contain traces of either 

 gasoline or paraffin products. 

 Kerosene should have a flash- 

 ing-point not below 44 C. 

 ( 1 1 1 F. ) , in order to render 

 fit safe for illuminating pur- 

 poses. The flashing-point of 

 kerosene may be approxi- 

 mately determined in the fol- 

 lowing way : 



Experiment 25. Testing kero- 

 sene. Pour into a small porcelain 

 crucible some kerosene ; place the 

 crucible upon a water-bath, and sus- 

 pend a thermometer in the kerosene. 

 Do not allow the water in the bath 

 to come in contact with the cruci- 

 Fig. 47.-Testing kerosene. ble Qr the thermometer to touch the 



bottom. Cautiously heat the water until the thermometer registers 

 40 C., then remove the lamp and draw a lighted match across the 



