REPORT OF THE CHEMIST. 



increases as b diminishes, the extreme importance of using the least pos- 

 sible quantity of water in the cells becomes evident. Indeed, the amount 

 of water employed, and the value of (h—flu are the factors which deter- 

 mine the number of cells requisite to reduce the specific gravity of the 

 liquid in the rejected chips to any given standard. In practice the num- 

 ber of cells employed lias varied irom six to eleven. 



HISTORICAL. 



The German chemist Margraff, who first detected the presence of 

 sugar in the beet in 1747, attempted its extraction by a process similar 

 to d illusion. 



Dombasle, in 1842, made the first attempt to apply the principle of os- 

 mose to the extraction of sugar from vegetable cells, on a commercial 

 scale. 



Dombasle was led to believe from his experiments that the process 

 of desaccharization could not be successfully carried on in the living 

 cell (i. e., fresh vegetable cells), but that it was first necessary to dry 

 them or heat them to 100°, in order to destroy the life of the cell. This 

 process he called " mortification." • 



On the beet roots, however, attempts to apply diffusion at a high 

 temperature resulted in obtaining a viscous juice, with a great tendency 

 to fermentation, and opposing considerable difficulties to crystallization. 

 This trouble comes from the fact that water near the boiling point 

 transforms the insoluble pectose, which exists in the beet in consider- 

 able quantities, into soluble peel inc. It was this substance that exerted 

 such an injurious influence on the juices. 



From the researches of Dubrunfaut on u osmose and its employment 

 in industry," the early workers of diffusion concluded that the exhaus- 

 tion of the pulp was more easy, as its division was more minute ; that 

 the natural adherence of the cells, as well as the gases contained in the 

 intercellular spaces, prevented the access of the diffusion fluid and re- 

 sisted the double current of osmotic force. 



It is true that after a certain time this force will overcome these ob- 

 stacles without the temperature being raised high enough to produce 

 mortification ; but in this case secondary effects are produced, which 

 interfere with the progress of diffusion. 



Under these supposed disadvantages the process of diffusion lan- 

 guished, except when it was used to prepare the juice for the dis- 

 tilleries. 



The problem was not solved until Eobert, in 1804, by a series of ex- 

 periments on a large scale at Seelowitz, in Moravia, proved that the 

 former ideas were incorrect, and that the process of diffusion could bo 

 carried on at a temperature not above 40°, producing a juice of remark- 

 able purity and quite free from pectine. 



To show the superiority of the juice obtained by this method over 

 that from the press, the following analyses are given: 





Press 

 juice. 



Diffnsion 

 juice. 



No. L 



Total solids 



13. 936 



10. 236 





11.25 

 .C03 

 2. 083 



8.41 

 .449 

 1. 377 



Ash 



Organic matter 



3 A — '84 



