Natural-Philosophical Collections. - 385. 
ligneous matter, which has an analogy to pectic acid, to the same treatment, and 
I ‘obtained the result I expected. 
- Five grains of cotton’ were put with 25 grains of pure potash and a little wa- 
ey into a platina crucible, and heated over a spirit lamp much beneath .redness. 
The cotton resisted the action of the alkali at first, but ultimately softened, the 
mixture melted without undergoing carbonization, and hydrogen was disengaged. 
During the tumefaction the mixture should be continually stirred. When it had 
settled down, the mass was dissolved in water, and rendered slightly acid by ni. 
tric acid. It then gave an abundant precipitate with nitrate of lead, and this, 
operated upon by sulphuretted hydrogen, produced very fine crystals of oxalic 
acid. With nitrate of lime, a voluminous precipitate of oxalate of lime was ob- 
tained. 
Wood sawdust, with the same treatment, gave the same result. 
Sugar, with 4 or 5 times its weight of potash, became, when heated, at first 
‘brown, then white, and gave much oxalic acid. 
Starch formed a very glutinous mass with potash, which long retained this 
state. More alkali occasioned liquefaction, the mixture swelled, and oxalate of 
potash was produced. 
Gum and sugar of milk were also converted into oxalic acid with the disen- 
gagement of hydrogen. 
The most remarkable transformation is that of tartaric acid into oxalic acid. 
There is no swelling, no-blackening, and (which merits particular attention) so 
little evolution of hydrogen, that it may be considered as due to extraneous ve- 
getable matter. When the hydrogen is to be collected, the experiment may be 
made in a retort to which a tube of glass has been attached, which is to be 
plunged beneath a layer of water into mercury to prevent absorption. The re- 
tort being heated by a bath of mercury or oil, it will be readily observed that a 
temperature of 400° F. at most is sufficient to form the oxalic acid. 
Citric and mucic acid produced also much oxalic acid. I have also obtained 
it from succinic acid, but the benzoic acid resisted the action of the potassa, and 
remained unaltered. 
. Acetate of potash heated with excess of potash became converted into carbon- 
ate. A little oxalic acid was obtained, but it is very probable that it was due 
to extraneous vegetable matter. 
Colza oil, notwithstanding a great excess of potash, could not be brought into 
fusion, and but very little oxalic acid was obtained. 
Amongst animal substances, silk, treated with potash, gave oxalic acid with 
disengagement of hydrogen. Uric acid evolved ammonia. The residue was 
very white; being dissolved in water, and saturated by nitric acid, hydrocyanic 
and carbonic acid were disengaged ; nitrate of lime then produced an abundant 
precipitate of oxalate of lime. Gelatine gave a similar result. Indigo gave no 
oxalic acid. 
Carbonate of potash used instead of caustic potash gave no oxalic from tartar ; 
nor did lime and starch produce any oxalic acid. Soda may be used instead of 
potash. 
From these experiments, it appears that a great number of animal and vegeta- 
‘ble substances, acted upon by.caustic potash or soda, are transformed into geile 
acid. It is to be remarked that the formation of this acid precedes that of car- 
‘bonic acid, and precisely under the same circumstances as when sulphur and 
potash, for instance, produce hypo-sulphurous and sulphuric acids. ‘Thus a ve- 
‘getable substance, heated moderately with potash, gives oxalic acid, but when 
more strougly heated, carbonic acid. 
As very different corbennces produce oxalic acid, it is necessary that other 
products should be formed. Many bodies evolve hydrogen which may come 
from themselves, or from the water they contain, and afterwards carbonic acid. 
Animal mattcrs, besides these two products, give also ammonia and cyanogen, 
Water must also be formed with both animal and vegetable substances, These 
YOL. I, SAAS 
