ON THE MANUFACTURE OF OXALIC ACID. 
241 
which I call benzohelicine. Benzohelicine is not decomposed by 
synaptase; but under the influence of acids and alkalies it is re- 
solved into hydruret of salicyle, benzoic and grape-sugar. Conse- 
quently this substance stands in the same relation to helicine as 
populine to salicine ; and it will perhaps be advisable to substitute 
the term benzosalicine for the word populine. Benzohelicine is 
converted into helicine when boiled with caustic magnesia, which 
removes from it the benzoic acid it contains, without altering the 
helicine. 
Before concluding this letter, allow me to communicate another 
fact, which may prove interesting to some chemists ; it is the exist- 
ence of the homologue of acetone in the aBthalic series. iEthalone 
is obtained with the greatest facility by distilling aBthalic acid 
quickly with an excess of slaked lime. In order to purify it, it is 
crystallized several times from boiling alcohol ; it separates in thin 
nacreous plates, which have the following composition : — 
Carbon - 82-46 82*94 62 = 372 82-67 
Hydrogen 13-94 14-04 62 62 13-73 
Oxygen - . . 2 16 3'55 
Chem. Gaz. March 1, 1852, from Comptus Rendus. 
ON THE MANUFACTURE OF OXALIC ACID. 
Oxalic acid is formed by the action of nitric acid on a great 
number of vegetable substances, such as sugar, rice, starch, washed 
sawdust, &c. 
Sugar, either in its crystalline state or in that of molasses or 
treacle, is the substance more commonly employed in the manu- 
facture of oxalic acid. 
On the addition of nitric acid to the saccharine solution and ex- 
posure to heat, a substitution of part of the oxygen of the nitric 
acid for the hydrogen of the sugar is effected, oxalic acid being 
formed and deutoxide of nitrogen evolved from the liquor. Other 
changes than this however take place ; carbonic acid is often dis- 
engaged with the deutoxide of nitrogen, and saccharic acid and 
other products remain in solution with the oxalic acid. 
