326 CHYMISTRY APPLIED TO AGRICULTURE. 



woven of pack-thread. These bags are placed upon the 

 plate of a good iron screw press, and submitted to a strong 

 pressure. The screws are after a time to be loosened, the 

 places of the sacks changed, the pulp which they contain 

 shaken over, and the whole again submitted to the action 

 of the screw. 



Sometimes the pulp is first acted upon by a cylindrical 

 press, by which about -^j^-^ of its juice is extracted, and the 

 operation is afterwards completed by means of the screw 

 press. But 10,000 pounds of beets may be pressed in a 

 day by the last alone. 



The pressure should be continued till the pulp will not 

 moisten the hand when strongly squeezed in it. The 

 juice which flows from the press, is carried by leaden 

 pipes into the boiler, where it undergoes the first opera- 

 tion. Of this I shall speak immediately. 



If an iron screw press is not to be had, a wine press, a 

 lever press, or a cylinder press will answer the purpose. 



The operation of the press should be completed nearly 

 at the same time with that of the rasp. Every thing that 

 has been moistened with the juice, must then be washed 

 so as to be ready for a new operation. The utmost clean- 

 liness must be preserved, otherwise the rasps will become 

 rusty, the juice will change, and the boiling will be rendered 

 difficult. 



The juice extracted from beets, is not always of the 

 same degree of concentration. It varies from 5° to 10°, 

 (= specific gravity of 1.036 to 1.075,) according to the size 

 of the roots, the nature of the soil in which they grew, and 

 the state of the atmosphere during vegetation. 



The juice of the large roots is less concentrated than that 

 of the small ones. The juice of such as grow in a light 

 soil, and have been exposed to heat and drought, marks 

 11°, (= specific gravity of 1.083;) but there is but little 

 of it. The greater the specific gravity of the juice is, the 

 greater is the proportion of sugar contained in it ; and, of 

 course, the greater is the saving of labor in the extraction 

 of the sugar. 



