Congelation of Quickjiker in England. 209 
I was dire&ed to the trial of this fait, by the like remarkable 
fenfation of coldnefs without pungency, which, with its 
other fimilar properties to ice, firft induced me, whilft pur* 
fuing the fubjeft of cold, to try the effefit of difiolving the 
vitriolated natron in the mineral acids. 
Equal quantities, by weight, of phofphorated natron and 
vitriolated .natron* were evaporated feparately over a gentle fire, 
until each was reduced to a perfeftly dry powder. I then 
weighed them, and found the refiduum of the phofphorated 
natron, fomewhat. lighter than that of the vitriolated natron ; 
from whence it is probable the former contains the greatefb 
quantity of water of cryftallization. 
I have found, that each of the neutral falts tvhich produce 
any remarkable degree of cold by folution in the mineral acids, 
viz*, phofphorated natron,, vitriolated natron, and vitriolated 
magnefia, lofe this property entirely,, when deprived, by any 
means of their water of cryftallization. 
A fhort time after I had firft fucceeded in freezing water in. 
fummer, by one mixture compofed of three different falts in 
water (having been induced to try the effecft of fuch a method,, 
from the confideration that water, already faturated with one 
kind of fait, will diffolve a portion of another, and after that 
a third, or even more), I met with the account of an experi— 
ment made by M. Homberg, related in one of the earlier 
Volumes of the PhilofophicaLTranfa&ions, in which it is faid 
he produced an extraordinary degree of cold, by pouring a pint 
and a half of diftilled vinegar upon two pounds of a powder, 
compofed of equal parts of crude fal ammoniac and corrofive 
fublimate, and fhaking them well together. I immediately 
(July 30, 1786), prepared a mixture of this kind in fmaller 
quantity,, but found it produced only thirty-two degrees of 
cold,. 
