ON THE PURIFICATION OF BEET JUICE, &C. 153 
property of decolourizing the syrup, but also of absorbing and 
retaining both the mucilage and the excess of lime. It would 
therefore appear, that it is merely necessary to filter the juice 
and syrups through a sufficient quantity of animal charcoal, to 
obtain the desired result. 
But animal charcoal is dear, and will become more so as 
the demand for it increases; added to which, the quantity 
required is very great. I have seen pound for pound of it 
used, and even this prove insufficient, entailing an expense of 
60,000 francs ($12,000) in the manufacture of 500,000 pounds 
of sugar, and perhaps it should have been doubled to have en- 
sured the best results. 
Manufacturers have therefore endeavoured to discover other 
means of removing the excess of lime, and it has been shown 
that this can be effected by means of an acid. Hence, in seve- 
ral establishments, alum and diluted sulphuric acid have been 
used; the solution of alum or the dilute acid being added to 
the syrup the moment it displays an excess of lime. 
These methods, however, are attended with serious incon- 
veniences; the sugar produced where an acid has been used 
being of a reddish colour, and having a burnt smell. 
Other chemists have proposed to saturate the excess of lime 
with carbonic acid, but at the same time admit the difficulty of 
doing so. I had myself thought of this plan, and made ar- 
rangements for executing it in my apparatus for boiling the 
syrup in vacuo, but on a mature consideration of the difficul- 
ties attendant on it, abandoned it as useless. 
I have found that to prevent the beet syrup from becoming 
red on concentration, there must be an excess of alkali, and 
also on the contrary that if this excess be too great, that the 
syrup will be ropy, and give a yellow and small grained sugar. 
The hot air apparatus of M. Brame accidentally produces 
the complete saturation of the alkali contained in the clarified 
juice; in fact, the small proportion of carbonic acid forming a 
constituent of the vast body of air which in this apparatus 
passes through the juice, is sufficient to precipitate the whole 
of the lime, and on this account, the sugar produced is of a 
VOL. II. — no. II. 20 
