260 Correspondence of J. Nickles. 
surface of the ingots, while the impure has a bluish tint 080 zine, and if 
the whole is not crystalline the upper surface is much more so than in 
pure aluminium, and the form is also quite different. heoiviing to one 
of the most extensive galvanising establishments of Paris, the metal 
works as well as silver. 
It may be whitened easily by dipping the piece in a concentrated 
solution of soda or potash, and passing it then into nitric acid. This 
acid acts differently according as it is itself pure or mixed with chlor- 
vious “jon ing. 
Fulminating power of Silver in the state of Sponge.—Correction. 
—The sponge of silver and not of silicium possesses the property 
fulminating ‘under a heavy peas suddenly applied—a property on 
which a remark was a the last number in connection with the 
observations of M. Che 
Physiological and ficebe oma Sc dpe of Carbonic Acid.—Some 
weeks since M. Herpin, of Metz, stated the following facts to the Aca- 
demy. Dr. Struve took the a esrint waters for a painfu! affection of 
the leg. He had been unable for several weeks to walk without a 
crutch. Dr. Struve had the notion one day of exposing his leg to the 
He con eued this ahi for some time, and has since experienc 
no aie of his co 
here are now in Ger many special establishments for baths, douches, 
and the inhalation of carbonic acid. sa ording to M. He erpin, the first 
On the occasion of this communication, i Boussingault related how 
Herpin. He was aren in the Quindiu, New Grenada, a ~_ of the 
attempted to descend in it in order to ascertain the temperature 5 
had hardly entered the crevice when he felt a suffocating heat, which 
he estimated to be at 40°C., and a pricking in the eyes; respiration 
being difficult, he ascended quickly ; ; his face was red and his pe rspira- 
tion abundant. fier a while he descended again with his thermome- 
ter, aA was surprised % find pp bbe of only 193°C. ‘The ex- 
tret mperature was 22°C. The gas was composed of 95 per cent. 
of catonis acid and 5 p.c. of snsauphaite air and sulphuretted hydro- 
