MITCHELL SUGAR BY EVAPORATION. 373 



Davidou's, its iron surface cannot be kept as clean as that of 

 the copper plane, nor can its open fire be as carefully regu- 

 lated as a steam supply. Yet the principle is one whose 

 adoption must lead gradually from one modification to another 

 till it end in the production of pure concrete or loaf sugar ; 

 this was probably not intended by Mr. Fryer, but to me the 

 conclusion appears to be inevitable and not remote. 



The second method of evaporation to which I would direct 

 your attention is the " Shower ;" a process which may dispute 

 the palm with the inclined plane of Dmitri Davidou or the 

 more recent Fryer's Concretor inasmuch as the surface it 

 exposes, either to steam or heated air, is practically unlimited, 

 and the heat does not rise high enough to scald the fingers, 

 The application is as follows : premising as in the preceding 

 mode that the cane-juice to be operated on is perfectly pure, 

 it is received into a vessel heated by steam or otherwise ; to 

 this is adapted a pump, endless belt or other suitable elevator, 

 which by its action raises the liquid to be evaporated to any 

 given height above the receiving vessel, into which it again 

 falls through a sieve or perforated surface in as many drop- 

 ping rills as there are perforations in the sieve ; through this 

 " Shower," which gives its name to the apparatus, dry or 

 heated air may be driven or not, according to the speed of 

 evaporation required. It is clear that by increasing the 

 height of the Shower and the amount of dry air driven 

 through its particles or drops, the superfluous moisture may 

 be driven off with such speed as to cause almost instantaneous 

 evaporation. The action of the apparatus when used with 

 water illustrates its power more clearly. When applied to a 

 vessel 3 feet wide by 5 feet long 2 feet deep, in which the 

 water was made to boil fiercely, the temperature of the water 



