122 Mr. Walker's Experiments on 
salt, even in the proportion of two to one, did not diminish the 
effect, determined the best and surest proportions to be, three 
parts of the muriate of lime to two of snow. 
But, since we shall find hereafter the temperature of -f 32 0 
to be a more convenient term of comparison, we may fairly state 
the fact thus ; that muriate of lime three parts and snow two 
parts, mixed at the temperature of 4- 32 0 , will give — 50°. 
The snow, to produce the greatest effect, he says, should be 
fresh-fallen, dry, and light or uncompressed ; and the salt per- 
fectly dry, and reduced to very fine powder. 
Pr. Lowitz's method is, to add at once the salt to the snow ; 
the latter being previously put into a convenient vessel. As the 
salt produces the greatest effect whilst it retains the greatest 
quantity of water of crystallization, he prepares it during a 
freezing atmosphere, pounds it, sifts it, and keeps it in close 
bottles, in a cold place. With a mixture of this kind, Pr. Lowitz 
froze, in one experiment, 35 pounds of quicksilver. 
Pr. Lowitz observes, that with the above precautions and 
management, it is impossible to fail in the design of freezing 
quicksilver with it. 
Pr. Lowitz found likewise, that the muriate of lime, pre- 
pared as above, produced 38 degrees of cold by solution in 
water ; that is, by adding 3 parts of this salt, in powder, to 2 
parts of water, each at the temperature of -j- 36°^-, the ther- 
mometer sunk to — i°i. 
Pr. Lowitz adds, that the muriate of lime which has been 
used for making frigorific mixtures, may be procured again 
repeatedly, as fit as at first for the same purpose, by evaporation 
and crystallization.* 
* The muriate of lime made use of by Professor Lowitz, in these experi- 
ments, was obtained from the residue after the distillation of caustic ammonia. 
