gaddesden's pan. 



117 



evaporating surface given to the syrup is increased as 

 much as possible. The wheel, half its circumference being 

 immersed in the liquid, is kept constantly revolving, so 

 that by exposing fresh portions of the heated syrup to the 

 action of the atmosphere, at each succeeding revolution, 

 the evaporation of the aqueous particles is rendered more 

 rapid than it otherwise would be, while the temperature is 

 at the same time in a corresponding degree reduced. The 

 time required to take off a skip in a pan containing one 

 ton of sugar, varies from two and a-half to four hours, and 

 the temperature of the syrup varies from 150° to 180° F. 

 From the principles upon which this method of concen- 

 tration are based, it is evident that its successful working 

 will depend on the degree of dryness of the atmosphere, and 

 on the rapidity with which the air passes over the surface 

 of the syrup. The apparatus should therefore always, 

 when it is practicable, be placed at the windward side of 

 the boiling-house ; at all events, it should be beyond the 

 influence of the vapours which arise from the evaporating 

 vessels." I have seen one of these pans tried in Antigua, 

 but it was merely an experiment, and the pan was not in 

 a convenient position. The temperature was easily kept 

 down to 170° F. The bars of the drum wheel were made 

 of wood instead of metal. Its uses have been successfully 

 applied by a gentleman in Berbice. I have a description 

 of its operation by the manager of the estate, which is 

 particularly interesting, from the fact, that some trials of 

 it in other places have failed, doubtless from want of atten- 



