244 
ON THE MANUFACTURE OF OXALIC ACID. 
obtained. Thus we find it stated, that from 50 to 60 lbs. of oxalic 
acid are obtainable from 100 lbs. of good sugar, whereas the quan- 
tity actually obtained in practice is from 125 to 130 lbs. Treacle 
of course gives a smaller product, 100 lbs. of fair quality yielding 
from 105 to 110 lbs. of oxalic acid. 
The mother-liquor having been poured off, the crystals of acid 
obtained are thrown on drainers and washed, and then carefully 
dried in a suitable stove. The mother-liquors, when treated with 
a fresh supply of nitric acid and treacle, are ready for a further 
operation. 
'About 4| cwts. of nitrate of soda and 2\ cwts. of sulphuric acid 
are used to furnish the nitric acid required to convert 1 cwt. of 
good sugar into oxalic acid. 
Mr. Jullion has patented a process for the conversion of formic 
acid into oxalic acid. For this purpose, formic acid is saturated 
with a solution of caustic potash, and then half the quantity of caus- 
tic potash required for saturation is added to the above mixture ; 
the whole is then evaporated to dryness, and heated to 560° F. By 
this process, the formic acid is decomposed, and oxalate of potash 
formed. Caustic soda may also be employed instead of caustic 
potash. 
The oxalate of potash or of soda thus obtained is then treated 
with sulphuret of barium, hydrate of baryta, or any soluble salt of 
baryta, whereby an oxalate of baryta is precipitated, from whence 
pure oxalic acid may be obtained by means of sulphuric acid. 
Another mode of obtaining oxalic acid is by the process patent- 
ed by Dr. Wilton Turner, who directs the uric acid obtained from 
guano to be treated with peroxide of lead or manganese suspended 
in water, at a boiling temperature, by which means it will be de- 
composed into oxalic acid, allantoin and urea. The oxalic acid 
forms an insoluble compound with the lead or manganese. The 
lead process is as follows: — A known weight of uric acid is 
placed in an open cylindrical iron vessel, capable of holding 2 lbs. 
of water for every pound of the acid, and adapted to boil by steam. 
A clear saturated solution of lime-water is then added, and as soon 
as it is heated and in brisk ebullition, the peroxide of lead is added 
in successive portions as long as it is observed to be whitened by 
the boiling liquid. The whitish powder thus obtained is oxalate 
