

-s//? WILLIAM SIEMENS, F.R.S. 321 



was a question open to discussion whether so large a diameter of 

 roller was beneficial in a chemical and economical point of view. 

 By using large rollers a greater amount of saccharine matter 

 could, however, undoubtedly be extracted. The system of raising 

 the juice from one receiver to another by a centrifugal pump, 

 instead of by the old 'blowing-up' arrangement, was also an 

 improvement ; because in admitting steam in contact with the 

 saccharine solution, condensation would take place, and the work 

 of evaporation would be increased ; and if the centrifugal system 

 was properly arranged, there need be no apprehension that it 

 would churn the saccharine solution. Considerable ingenuity had 

 been displayed in the construction of the evaporating apparatus 

 employed. The steam boiler had been placed immediately below 

 the concentrator, or, as it was called, the 'juice boiler,' and thus 

 the steam generated in the lower compartment at once condensed 

 against the upper surface of the steam boiler, which was also the 

 bottom surface of the juice chamber the surface contact being 

 increased by means of tubes and in that way losses of heat by 

 radiation or otherwise were avoided, and the same water was re- 

 evaporated again aud again. It was interesting to observe that 

 the surface in contact with the fire could be made three or four 

 times smaller than the surface necessary to convey the heat from 

 the steam to the saccharine solution. 



The use of the steam raised from the saccharine solution was 

 another novelty. It was made serviceable not only for working 

 the vacuum pan, but also for driving the engine. There could be 

 no reasonable doubt about the mechanical efficiency of applying 

 the steam raised from the juice to drive the engine, and theory 

 in this case had been justified by the result ; but a question of a 

 chemical nature arose, namely, whether the juice itself was not 

 injured by raising from it steam of sufficient pressure for such 

 purposes. It was well known that when juice was concentrated 

 by the direct application of fire, a considerable portion of the 

 sugar was converted into molasses, or uncrystallizable sugar, and 

 it would be desirable that the opinion of persons practically 

 engaged in sugar-boiling operations should be ascertained as to 

 whether the direct application of heat had not been earned too 

 far, or whether the same amount of juice would not have yielded 



VOL. II. Y 



