246 
ON THE MANUFACTURE OF OXALIC ACID. 
vessel," which is a vessel something like a Woulf's bottle, only 
having a moveable top fitting air-tight, and capable of holding 
about 100 gallons. The materials to form the oxalic acid are in- 
troduced, and the vessel heated by a water-bath (by steam or other 
convenient means,) which surrounds the vessel; a quantity of ni- 
tric acid is then added, and air or oxygen is forced in through a 
pipe inserted in the top. The oxygen, coming in contact with the 
evolved oxides of nitrogen, immediately converts a portion into 
nitrous and hyponitrous acids, which are partly again absorbed by 
the fluid in the vessel ; another portion passes off by a pipe in- 
serted in the upper part of the vessel, which pipe passes through a 
furnace. This part in the furnace is a little enlarged, and is heat- 
ed to from 600° to 900° F. ; this part of the pipe or tube contains 
spongy platinum, or other similar substances. The gases, on com- 
ing in contact with the heated platinum, combine to form nitric 
acid, which is afterwards condensed in vessels arranged as usual 
in the manufacture of this acid. Instead of platinum, a close ves- 
sel containing water may be used, which decomposes hyponitrous 
and nitrous acids, giving rise to nitric acid. This principle is ap- 
plied in the following ways : — The oxides of nitrogen, as evolved 
from the liquor in the decomposing vessel, coming in contact with 
oxygen, are converted into hyponitrous and nitrous acids, which, 
upon being mingled with steam, are decomposed into nitric acid 
and deutoxide of nitrogen; or the introduction of steam may be ob- 
viated by using heated air or oxygen in the decomposing vessels, 
by which means moisture will be furnished from the liquor; the 
amount of evaporation thus caused will also prevent an inconve- 
nient increase of the mother-liquor. The compounds thus formed, 
when passed through suitable condensers, will, if the supply of at- 
mospheric air or oxygen has been in excess, be all or nearly all 
condensed into nitric acid. 
The following is a description of Crane and Jull ion's continuous 
method of manufacturing oxalic acid and nitric acid at one process : 
The oxalic acid mother-liquor of a previous process is placed in 
a closed or covered vessel termed a " generator," formed of slate; 
nitric acid and syrup in the usual proportions employed for such 
quantity of mother-liquor, are also placed separately in feeding 
vessels, over the "generator;" heat is then applied to the mother- 
