*35 
the Production of artificial Cold. 
shall conclude by exhibiting a general view of the different 
frigorific mixtures composed of chemical substances with ice, 
as I have before done, (Phil. Trans, for 1795, page 279,) of 
those in which the use of ice is dispensed with. 
Class I. 
Acids and salts. Ice. 
Muriate of soda i, - - - - - - - - - - - - Snow 
. 2, Muriate of ammonia i, - - - - - 
— — jo, 5, Nitrate of potash 5, 
5, Nitrate of ammonia 5, - - - ~ - 
Temp, of mat. Temp, os- 
beforc cold 
mixing produced 
2, 5 0 
5, . - 12° 
24, - . 1 8° 
12, - - — 25° 
Class II. 
Diluted vitriolic acid 2,* ------ - - - Snowf 3, d- 3 2 ° — 2 3° 
Concentrated muriatic acid 5, - ------- 8 , +32 0 — 27 0 
Concentrated nitrous acid 4, f - - -- -- -- 7, + 3 2 ° — 3 °° 
Muriate of lime 5 , H - - ■ — - 4 » + 3 2 ° — 4 °° 
3 >f - * - - - - - - - 2 > + 3 2 ° — 50 ° 
Caustic vegetable alkali 4, - - - -- -- -- 3, +32 0 — 51 0 
must commonly be prepared for this alone ; hence it may not unfrequently happen 
that the former, on this account, may be preferred. 
• Concentrated vitriolic acid, diluted with half its' weight' of snow, or distilled water, 
and cooled. 
f Snow that is fresh, dry, and uncompressed, or such as has never been subject 
to the effects of a temperature less than freezing ; or, when such is not to be procured, 
ice reduced to powder, in the manner described in Phil. Trans, for 1795, p. 271, 
may be substituted in its stead, with equal effect. 
t Concentrated fuming nitrous acid alone ; or concentrated pale nitrous acid, diluted 
with one-fifth its weight of snow, or distilled water, and cooled. 
|| Of the strength of 1,490, at 8o° of heat. 
Of the strength of 1,450, at 8o°of heat. 
