Miscellanies. 359 
_ ready extensively practised on the continent. ‘The introduction of 
_ this improvement is chiefly due, I believe, to Mitscherlich. It is 
founded upon the principle that alcohol, by absorbing oxygen, is 
_ changed into acetic acid and water. For, two alcohol+ four oxygen 
=one acetic acid+ three water (6H+ 4C+2Q0) +40=(8H+4C 
+30) +3 (H+0.) 
This oxidation is promoted by the process of fermentation ; and 
_ when the fermentation has begun, is much accelerated by the pres- 
ence of acetic acid. ‘The oxidation is effected entirely at the ex- 
_ pense of the oxygen of the air :—to accelerate the process, therefore, 
by producing as many points of contact as possible between the li- 
quid and the air, the following arrangement is adopted. A large cask 
is taken, placed upright with a stop cock at the bottom and a series 
of holes, half an inch in diameter, bored one in each stave, a few 
inches above it. It is then nearly filled with chips or shavings of 
wood, previously steeped in strong vinegar till they are perfectly 
saturated. Within the upper end of the cask a shallow cylindrical 
vessel is placed, nearly in contact with the shavings, the bottom of 
which is perforated with many small holes, each partially stopped 
with a slender twig which passes an inch or two beneath the perfor- 
ated bottom of the cylinder. ‘The alcohol diluted with eight or nine 
parts of water, and mixed with the fermenting substances, is now 
poured into the cylinder, through the bottom of which it trickles, 
drop by drop, upon the shavings below, becomes oxidized in its pas- 
sage, and runs out at the stop cock beneath, already converted almost 
entirely into vinegar. ‘The air rushes in by the holes beneath, and 
passes out above by eight glass tubes, cemented for that purpose into 
the bottom of the cylinder; and so rapidly is it deprived of its oxy- 
gen, when it escapes above, that it extinguishes a candle. During 
the process much heat is also developed; so that from the temper- 
ature of 60° (that of the room,) the interior of the cask rises as high 
as 86° I’. In the proper regulation of this temperature, much of 
the difficulty consists. 
A second transmission of the acid, thus obtained, through another 
similar cask, finishes the process. ‘The whole is concluded in a few 
hours, four and twenty is considered amply sufficient to convert a 
given quantity of alcohol into vinegar.—Idem. 
7. Opium. J.G.—Few substances have undergone more repeated 
investigations than opium, or been subjected to more varied chem- 
