IMPROVEMENTS IN THE REFINING OF SUGAR. 51 
leaving the liquor above in a greater or less degree of tran- 
sparency. The syrup is now filtered through bags, and is 
received into copper vessels. It will be found to contain a 
quantity of lead, for the separation of which sulphurous 
acid gas is passed through it. The patentee states that the 
precipitation of the lead by this means is complete. He 
recommends that, before the use of the gas is suspended, the 
filtered liquor should be tested for lead with solution of sul- 
phuretted hydrogen, or sulphuretof ammonium. The lead 
being thus removed, the saccharine liquor will still retain 
free sulphurous acid and the acetic acid originally in com- 
bination with the lead. It is now rapidly heated to 180° 
Fahr., and chalk or powdered marble added to neutralize 
the acid. After concentrating it to a proper degree it is 
either crystallized at once, or further purified with animal 
charcoal. 
In applying the process for the refining of cane-juice, the 
latter is first neutralized with lime or chalk, and the basic 
acetate of lead then added in the proportion of 150 grains to 
the imperial gallon of juice. The subsequent parts of the 
process are conducted in the same manner as in the case 
previously alluded to. 
The efficacy of basic acetate of lead for the purpose for 
which it is used in this process cannot be doubted ; and if 
the subsequent removal of the excess of lead from the solu- 
tion can be completely ensured by the means specified, the 
process will probably possess some important recommenda- 
tions, especially in the manufacture of sugar from the juice 
of the cane or beet root. In the discussion which took place 
on the subject at the Birmingham meeting, two objections 
were urged to the process; — first, that although a Chemist, 
operating in his laboratory, may completely remove lead 
from its solution by means of sulphurous acid, yet that the 
workmen employed in the manufacture of sugar would be 
likely occasionally to be less successful ; and secondly, that 
acetate of lime would necessarily be left in the molasses. 
