ON THE SOLIDIFICATION OF CARBONIC ACID. 309 
At — 146° sulphuric ether is not in the slightest degree 
altered. 
When a piece of solid carbonic acid is pressed against a 
living animal surface, it drives off the circulating fluids and 
produces a ghastly white spot. If held for fifteen seconds it 
raises a blister, and, if the application be continued for two 
minutes, a deep white depression with an elevated margin is 
perceived; the part is killed, and a slough is, in time, the con- 
sequence. I have thus produced both blisters and sloughs, 
by means nearly as prompt as fire, but much less alarming to 
my patients. 
The specific gravity of liquid carbonic acid may be estimated 
either by weighing a given measure of it in a tube, and de- 
ducting the w T eight of the tube and of the superincumbent 
gas, or by means of very minute bulbs of glass, as suggested 
by Sir M. Faraday. By the latter means, I obtained the fol- 
lowing results, which are compared with those of Thillorier : 
Thillorier. 
Tern. Fahr. 
Sp. Gr. 
Temp. Fahr. 
Sp. Gr. 
32° 
.93 
32° 
.83 
43°.5 
.8825 
51° 
.853 
74° 
.7385 
86° 
86° 
.60* 
The specific gravity, particularly at 32°, was examined re- 
peatedly, and with different bulbs, and always found to be at, 
or very near to, .93. The difference never amounted to .005. 
The specific gravity, as given by Thillorier at 32°, is 83. 
The anomalous expansion of the liquid, as indicated by both 
* The discrepancy in the above results may arise from the difference 
in the mode in which the specific gravity was ascertained. M. Thillorier 
noted the alteration of the gravity by the enlargement of bulk, as marked 
by graduated tubes; Dr. M. by the use of specific gravity bulbs. This 
latter mode will afford more accurate results, and any alteration in the 
bulbs by pressure would be still more against Thillorier's views. 
R. B. 
VOL. IV. NO. IV, 40 
