ON THE MANUFACTURE OP ARTIFICIAL GUM. 287 
the starch soluble, as in the former process, by means of a 
small dose of acid, and by torrefaction or rather desiccation, 
at a high temperature. 
The powder thus obtained is afterwards thrown upon a 
metallic sieve, and submitted to the action of a jet of steam, 
which damps the dextrine to such an extent as to render it 
transparent without liquefying it ; so that it will require 
but very little drying afterwards. This process possesses 
the disadvantage of requiring great ability on the part of 
the workmen charged with the hydration of the dextrine. 
The manipulation necessary for this operation is not ac- 
quired without great difficulty ; so much so, indeed, that M, 
Saint Etienne, jun., who directs the working of his process 
in England, has not yet been able to find any person capa- 
ble of undertaking this part of the work. Messrs. Saint 
Etienne prefer to use hydrochloric acid. 
By Diastase, — This process seems the most worthy of 
attention in all respects; as, by adapting to it some modifi- 
cations, which I have tried on a large scale, it will be found 
to be the one giving the most perfect results. I will there- 
fore describe it fully. 
The fecula must be rendered soluble in vats, heated by 
steam in such a manner that the temperature may be easily 
raised or lowered. The fecula is first mixed with 4 times 
its weight of water, previously heated to about 122°; for this 
purpose the fecula is gradually introduced into the vessel 
or boiler containing the hot water. In London, I employed 
copper boilers, with a double bottom, capable of containing 
about 400 gallons; and at one operation, about 600 lbs. of 
fecula, mixed with 1200 quarts of water, were decomposed. 
The temperature must be kept at about 140° until the whole 
mass is converted into starch ; 2 per cent, by weight of very 
white malted barley must then be added, and also the mu- 
cilage produced from 1 per cent, of linseed. 
If a greater proportion of malt than that which I have 
mentioned were added, the decomposition would doubtless 
