134 MAIiUAL FOB SUGAR GROWERS. 



is the usual strengtli of commercial rum. Spirit of 

 a density from .864 to .900, or from 40 to 50 over- 

 proof, is termed high wines, while weak spirit, from 

 .900 to .967, or from 15 over-proof to 50 under-proof, 

 is termed low Avines, and from both of these spirit 

 of full strength is recovered by redistillation. This 

 redistillation is often economically effected by plac- 

 ing a quantity of low wines in the first retort and 

 high wines in the second, the heat of the vapour 

 from the wash in the still driving the alcohol, in a 

 high state of concentration, into the condensing- 

 worm. 



In large distilleries what are known as continuous 

 stills are employed. There are a great many modi- 

 fications of this kind of apparatus ; the principles 

 underlying their construction and method of work- 

 ing will be understood fi'om Fig. 20 and the follow- 

 ing brief description. 



The chief parts of the apparatus are : A, the 

 wash -tank'; B, condenser; C, the rectifying - col- 

 umn ; D, the condensing-worm. 



The wash flows, in the direction indicated by the 

 arrows, from the wash-tank into the condenser, 

 where it serves to cool the vapour which passes 

 from the rectifying -column into the worm of the 

 condenser ; from the condenser the wash, now par- 

 tially heated, flows by means of a pipe into the 

 rectifying-column. This contains a number of hori- 

 zontal plates or discs, perforated, yet so arranged 



the other hand, the quantity of water in the spirit was so great as 

 to render the gunpowder too wet to burn, the spirit was said to be 

 ' ' under-proof. ' ' 



