[ 126 ] 
therefore, which I have formed from what I have hi- 
therto feen is, that the boiled and common water differ 
from one another in this refped: ; that whereas the com- 
mon water, when expofed in a If ate of tranquillity to air 
that is a few degrees colder than the freezing point, may 
ealily be cooled to the degree of fuch air, and ffill conti- 
nue perfecftly fluid, provided it ftill remain undiffurbed : 
the boiled water, on the contrary, cannot be preferved 
fluid in thefe circumlf ances ; but when cooled down to 
the freezing point, if we attempt to make it in the leaf! 
colder, a part of it is immediately changed into ice ; after 
which, by the continued a6fion of the cold air upon it, 
more ice is formed in it every moment, until the whole 
of it be gradually congerded before it can become as cold 
as the air that furrounds it. From this difeovery it is 
eafy to underfland, why they find it necelTary to boil the 
water in India, in order to obtain ice. The utmoff in- 
tenfity of the cold which they can obtain by all the means 
they employ, is probably not greater than 31° or 30'' of 
Fahrenheit’s thermometer. Common water, left un- 
diflurbed, will eafily defeend to this degree without freez- 
ing; and, if they have not the means of making it colder, 
may continue fluid for any time, provided it be not dif- 
turbed : the refrigerating caufes of that part of the world 
when they have done fo much, have done their utmoff, 
and can a6f no further upon the water. But this cannot 
happen to the boiled water; when the refrigerating 
caufes have cooled it to 3 2°, the next effedt they produce, 
,is to occafion in it the beginning of congelation, while 
the 
I 
