SCIENTIFIC SUMMAEY. 
655 
ness. After heating, it is said that the wine may be exposed to the air 
without fear of its becoming acid. As regards the flavour of wine treated 
by the author’s process, he states that a professional taster, who had made 
comparative experiments without knowing which had been submitted to 
treatment and which had not, gave a preference to the treated wines in nine 
cases out of ten. — Vide Comptes Bendus, Aug. 14th. 
The Death of Signor Firia was announced to the French Academy at one 
of its meetings in August, by M. Dumas. Signor Piria was well known to 
chemists through his researches on Salicine. 
The Action of Mycoderma Aceti in Fermentation. — In a late number of the 
Annates d^Ecole Normale, M. Pasteur has written a valuable paper on the 
phenomena which take place during the formation of acetic acid. The 
fermentation in which this compound is produced arises, says the writer, 
from the exclusive influence of a living organism {Mycoderma aceti), a very 
simple vegetable, which consists essentially of frames of little joints slightly 
compressed towards the middle, and measuring the -s^Vcr of a millimetre in 
width, and about twice as much in length. However much it may be charged 
with albumenoid matter, no alcoholic liquid has ever been known to produce 
acetic acid without the presence of this my coderm. On the contrary, if a 
trace of this organism be placed on the surface of an albumenoid liquid 
alcoholic or slightly acid, it is immediately seen to develop like a filmy veil 
over the surface ; and, by a correlative action, the oxygen of the air in con- 
tact with the liquid disappears, and the alcohol acetifies. It is not necessary 
for the liquid to contain albumenoid matters ; if the fungus finds, besides 
the alcohol, a small quantity of alkaline and earthy phosphates, it will live, 
and its action be the same as before — a circumstance which proves that the 
albumenoid matter is not the ferment, but the food of the fermenting myco- 
derm. When alcohol is present, it is, as described above, converted into 
acetic acid ; but the power of the ferment does not stop here : if there be 
no more alcohol, it will operate on the acetic acid, and convert it into water 
and carbonic acid. Such is the action of the mycoderm under ordinary cir- 
cumstances ; but it sometimes alters, and, having no longer the same con- 
sistence or appearance, its effects are different. It is then capable of pro- 
ducing the combustion of the alcohol to the acetic stage, and gives inter- 
mediary products with a suffocating odour, and which have already been 
obtained by the oxidation of ether and alcohol by platinum black. 
Nitro-glycerine and its Phenomena. — Nitro-glycerine, a compound which 
was discovered in 1847 by M. Sobrero, a pupil of M. Pelouze, has recently 
been very carefully examined, and its explosive properties demonstrated, by 
M. Nabel. It is formed by acting on glycerine, the sweet principle of oils, 
with nitric acid, and consists of one part glycerine and three nitric acid ; it 
is an oily liquid, heavier than water, and is soluble in alcohol and ether. Its 
properties are very remarkable. It produces such a powerful effect on the 
nervous system, that a drop of it placed on the tongue causes a headache of 
great violence, which lasts several hours. It is highly explosive, and ten 
times more powerful than gunpowder. M. Nabel, who is a Swedish engineer, 
availing himself of this latter property, has used it with great effect in 
mining, and with a diminution of expense to the amount of 50 per cent. It 
requires a smaller chamber than gunpowder, and a mere fissure will do, if 
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