HOT DIFFUSION FACILITATES PRESSING. 175 



hydraulic presses, as once suggested. With the modern cossette 

 presses there would be no advantage in pushing this pressure 

 beyond the limit it now attains, when drying is the object in 

 view, as practical experience shows that when this pressure has 

 attained a certain crushing limit, drying them is next to impos- 

 sible, as the heated gases that are in such furnaces cannot ac- 

 complish the object in view. They would carry with them 

 during their circulation a large percentage of the finer particles 

 of which the product consists. 



Buttner & Meyer some years since forced the cossettes through Liming before 

 perforated cylinders combined with a slanting spiral arrange- drying, 

 ment which was in close communication with another recept- 

 acle containing milk of lime, in which the residuum became 

 saturated with lime. It was subsequently stramed before leav- 

 ing the upper parts of the cylinder. 



Without doubt, lime has great influence upon the cellular 

 texture of the beet slices being treated, and will often permit a 

 greater percentage of water to escape; but independent of certain 

 mechanical complications that we need not mention here, there 

 is always danger of hardening the cossettes. It frequently 

 happens that the fuel used for the drying in this appliance con- 

 tains sulphur. The gases of the furnaces will then be saturated 

 with anhydrous sulphurous acid, which, coming in contact with 

 the lime of the cossettes during their working in the Buttner & 

 Meyer dryer, w^ould result in a certain calcic deposit. 



Herzfeld called attention to the fact that after a reasonable 

 period of keeping, this dry residuum threw out sulphuretted 

 hydrogen, notwithstanding the fact that it contained almost 

 insignificant traces of this chemical. 



At the present time, liming of residuum cossettes has been 

 practically abandoned, and there remain now only the natural, 

 dry cossettes, which product is becoming yearly more and 

 more popular. 



As the emptying of the diffusors of the diffusion battery may Hot diffusion 

 now be automatically accomplished, the battery may be worked Jac||ita{es 

 at a high temperature. This greatly facilitates pressing, as it is 

 practically shown that cossettes lose, during their pressing when 

 hot, a greater percentage of water than when pressed cold. 



