[ 25 ^ ] 
From thefe circumftances it aj^pears, that water, by 
being placed in a fituation free from receiving heat from 
other bodies, and expofed in large furfaces to the air, 
may be brought to .freeze when the temperature of the 
atmofphere is fome degrees above the freezing point on 
the fcale of Fahrenheit’s thermometer; and by being 
colle6led and amafled into a large body, is thus prefeiwed, 
and rendered fit for freezing other fluids, during the fe- 
vere heats of the fummer feafon. In effecting which 
there is alfo an eftabliflied mode of proceeding; the fher- 
bets, creams, or whatever other fluids are intended to be 
frozen, are confined in thin filver cups of a conical form, 
containing about a pint, with their covers well luted on 
with pafte, and placed in a large veffel filled wdth ice, falt- 
petre, and common fait, of the two laft an equal quantity, 
and a little water to dilTolve the ice and combine the whole. 
This compofition prefently freezes the contents of the 
cups to the fame confiftency of our icecreams. Sec. in Eu- 
rope ; but plain water will become fo hard as to require a 
mallet and knife to break it. Upon applying the bulb of a 
thermometer to one of thefe pieces of ice, thus frozen, the 
quickfilver has been known to fink two or three degree 
below the freezing point : fo that from an atmofphere 
apparently not mild enough to produce natural ice, ice 
fliall be formed, col levied, and a cold accumulated, that 
fhall caufe the quickfilver to fall even beloAV the freez- 
ing point. The promifing advantages of fuch a difco- 
very could alone induce the Afiatic (whofe principal ftudy 
the luxuries of life, and this may well be called fuch, 
when 
