115 



To produce this separation is the great object of the suopr- 

 boiler. This is partly clone by the application of heat, the 

 gluten coagulating and assuming the solid form, under the 

 appearance of olive-green flakes, and rising to the surface as 

 scum. It is also partly accomplished by some of the earths 

 and the alkalies. In the present backward state of veo-etable 

 chemistry, in this respect, we cannot distinctly state their 

 imdus operandi. We know that vegetable extractive forms 

 an insoluble compound with alkalies and the sulphate of 

 alumina. They also unite with the gluten, of which frreen 

 fecula is principally composed, forming with it a kind of 

 soap, converting it into oil and ammonia. The union of 

 this last substance with water is very slight, since, as has 

 been just mentioned, it coagulates readily on the applica- 

 tion of heat. 



As for the acid which is said to be present in the cane- 

 juice, it must, when the Canes have attained a full aire, be 

 very small in quantity. When, on the contrary, they are 

 in a green state, or when they have been allowed to remain 

 for some time in the cane-yard, or when the juice itself has 

 been allowed to stand over, or the vessels for receiving it 

 have not been properly cleaned — in all these cases there can 

 be no doubt that an acid, most probably the acetic, is present. 

 It is equally certain, that unless neutralised, it may prevent 

 the proper crystallization of the sugar. That the propor- 

 tion of it, however, must be very small in the juice of ripe 

 Canes, recently expressed, may be proved by the circum- 

 stance that it crystallizes readily without the addition of any 

 temper, or with the addition of salts, such as the sulphate 

 of alumina, or of potass, which could have no eflect in 

 neutralising an acid. 



Lime is the alkali most commonly employed. The pro- 

 portion of it to the liquor varies with the richness of the 

 liquor, less being required for the Bourbon than the Violet 

 or Ribbon Canes — for a field which has been properly trashed 

 and weeded, than for one which has grown up in rank 

 luxuriance — for the produce of a dry, than for that of a wet 

 season or parish. Where too little lime is useil, the sugar 



