Feb. 1, 1865.1 THE TECHNOLOGIST 



COSSIPORE SUGAR WORKS, BENGAL. 289 



shaped copper vessel, half of which is sunk below the floor, and pro- 

 trudes through the ceiling of the next story. This vessel is called a 

 " vacuunipan." Formerly great difficulty was experienced in sugar-boiling 

 for the following reason : — In an open pan the liquor would not boil, and 

 consecpiently would not crystallize, except at a temperature of 212°. But, 

 unluckily, this high heat restored all the colour which the charcoal had 

 so laboriously removed. For a long time the dilemma appeared insuper- 

 able, until it was ingeniously suggested that if the air were pumped out 

 of an air-tight pan, the liquor would boil at a much lower temperature. 

 (There is a well-known chemical experiment whereby water, in a 

 Florence flask, is made to boil by the mere heat of the hand.) Practical 

 sugar-boilers find that complete exhaustion is not advisable, but with 

 the air-pump attached to the vacuum pan they reduce the boiling point 

 to about 140°. This allows the syrup to crystallize without discolour- 

 ation. Should the foreman wish to test how the process is going on, he 

 withdraws an ingeniously-contrived little brass cylinder, called a "proof- 

 stick " from the side of the pan (like a spigot from a barrel). This 

 " proof-stick " is so constructed that, without admiting a particle of air, 

 it extracts a sample of crystallizing syrup, just as a cheese-taster extracts 

 a sample of cheese. 



6. When the syrup has boiled long enough, a plug is drawn out of 

 the bottom of the vacuum pan, and the whole contents, now thick, viscid, 

 and apparently somewhat discoloured, resembling honey in consistence, 

 are allowed to fall into a large open vessel beneath. We have now 

 reached the ground floor. The syrup is then ladled into small circular 

 pans, called " drums," perforated at the sides, like a cullender, with 

 numerous holes. A metal cap is placed over these drums, and they are 

 then attached to the machinery, and spun round at a prodigious rate. 

 In a few seconds a marvellous change has been effected. All the water 

 and molasses have escaped through the holes, being prevented by the 

 metal cap from spirting over the apartment ; and the residue has become 

 manufactured sugar, perfectly dry, brilliant and beautiful, well deserving 

 to aid in ornamenting a grocer's Christmas window. 



We have not space to enter upon many other interesting details, but 

 we will touch on two or three points*: — 



1. The so-called molasses, just spoken of, contains a considerable 

 percentage of sugar, and is boiled several times over until it has yielded 

 up all its crystallizable particles. It is then shipped under the name of 

 " treacle." 



2. Only the yellow sugar made at Cossipore finds its way to this 

 country. The differential duty shuts out the higher kinds, which are 

 purchased for the Arabian and Australian markets. The Hindoos refuse 

 to eat our sugar, because it has been defiled by passing through animal 

 matter. The crystals vary greatly in form and appearance. The finest 

 and strongest resemble a miniature sheet of plate glass, being perfectly 

 square, with an invariable line down the centre. 



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