MISCELLANY. 
On some new substances from Tobacco.' — By M. Barral. — The juice 
obtained by digesting tobacco-leaves in water is strongly acid. This 
acidity has been attributed by Vauquelin to the presence of malic acid ; 
but on crystallizing the syrup, either under the air-pump or at a gentle 
heat and exposure to the air, I obtained an acid in micaceous lamella?, 
soluble in water, yielding an insoluble salt of lead and crystalline com- 
binations with ammonia, nicotine, potash, &c. 
This acid ; which I shall call nicotic, is represented by the formula 
C 3 H0 3 + H O, and its lead and silver salts by C 3 H O 3 + PbO and 
C 3 H O 3 AgO. The great tendency which this acid has to form double 
salts, and all the reactions which it yields, lead to the presumption that 
the preceding formulae should be doubled. It is decomposed by heat 
and sulphuric acid into acetic and carbonic acids. 
This acid appears to stand in the same relation to metacetonic acid 
as oxalic acid does to acetic acid. 
The essence of tobacco or nicotianine contains nitrogen ; on distillation 
with potash it yields nicotine. Tts composition is — 
Caibon 71.51 
Hydrogen 8.23 
Nitrogen 7.12 
Oxygen 13.12 
Chem. Gaz. from Comptes Rendus. 
Employnent of Rochelle Salt in Dyeing. — By J. A. Benckiser. — The 
potassio-tartrate of soda may be substituted in all cases in the dyeing 
of wool, both for the crude as well as for the purified tartar; it has even 
several advantages over it. It is pure, always of the same composition, 
and readily soluble in water, while the bitartrate of potash is so fre- 
quently mixed with foreign ingredients that often only 50, rarely more 
than 70 per cent, of pure bitartrate can be obtained from it. The im- 
purity in the colon i of the tartar may very readily injure that of the 
cloths; the fibrous parts of the tartar adhere to the wool, and the frag- 
ments of sulphur which frequently occur in it make spots • moreover, 
a portion frequently remains undissolved in the water, and is lost. The 
