354 Dr. Kane on the Action of Hydrochloric Acid on 
version of the ordinary rules of chemical affinity. The sul- 
phuric acid ranks much higher in affinitary [?] power than the 
muriatic acid, and yet is completely displaced by the latter 
from its state of union with the black oxide of copper. The 
theory of this reaction is very easily understood. ‘These are 
(S + Cu +5H)+ CIH, and there are. formed (Cl + Cu) 
+S+6H. The sudden liberation of the larger quantity of 
water from its state of solidity in bluestone produces the re- 
markable reduction of temperature. 
I have sometimes observed that when the crystallized chlo- 
ride of copper is allowed to remain for a long time in contact 
with the strongly acid mother-liquor, a reverse action is set 
up, and small crystals of sulphate begin to appear disseminated 
through the mass. I several times analysed these crystals, in 
order to ascertain whether a sulphate of the chloride of copper, 
like Peligot’s chromate of the chloride of potassium, would 
be formed, but without effect ; no definite compound could be 
detected. 
The interesting nature of this reaction made it important to 
ascertain the action of sulphate of copper upon dry muriatic 
acid gas. ‘The experiments for this purpose were conducted 
in the following manner. A bulb tube was connected at the 
ends with strong glass tubes containing fragments of dried 
chloride of calcium. The one tube was by its other extremity. 
connected to a retort, in which muriatic acid gas was disen- 
gaged by the action of oil of vitriol on fused chloride of so- 
dium. ‘The other desiccating tube was of much smaller size, 
so as to allow of being weighed in a delicate balance ; to the 
remote extremity of this a small quill tube was attached, by 
which the excess of gas made its escape. ‘The sulphate of 
copper in fine powder was introduced into the weighed bulb 
tube, and the whole then weighed to determine the quantity 
employed ; the desiccating tubes were then attached, and the 
muriatic acid gas disengaged. Having been dried in its pas- 
sage over the first chloride of calcium, it came into contact 
with the bluestone, by which it was rapidly absorbed; and any 
water that was formed or disengaged, carried away by the 
current of dry gas in excess, was deposited in the small de- 
siccating tube, where its quantity could be accurately deter- 
mined. 
When the crystallized bluestone (S Cu+5 H) in fine pow- 
der is put into the tube, it absorbs rapidly thé$muriatic acid 
gas, and becomes grass green: great heat is produced. Drops 
of moisture appear on the cold portions of the tube. It loses 
