C 3^2 ] 
confiderably increafed in bulk, fo as to rife at its 
furface into a very convex form. The water, when 
thawed, was white and turbid, and foon let fall 
its metallic and abforbent earths in a white fediment : 
it then had almoft loft its tafte ; and, being mixed 
with tindfure of galls, only gave therewith a flight 
purple tinge. By a fecond congelation, it feemed 
almoft entirely deprived of its air, and, with it, of 
the remaining part of its white earths ; and, when 
decanted from its fediment, no longer ftruck a co- 
lour with galls. From thefe experiments it therefore 
appears, that fo foon as this water is deprived of its air, 
whether it be by heat or by cold, it is no longer ca- 
pable of keeping thofe earths diflolved, which, while 
it is impregnated with this air, continue fufpended 
therein. 
In thefe decompofitions of the pouhon water, by 
heat and by cold, no volatile fpirit, either acid or 
fulphureous, nor any other fubtile matter, has been 
found to fly from it, fave only its mephitic air : 
while this air is prefent in the water, its martial and 
abforbent earths remain diflolved therein ; fo foon as 
this air is feparated from the water, in whole or in 
part, thofe earths, either in the whole or in part, do 
alfo feparate from it, and are no longer fufpended 
therein, than while they are united to a due propor- 
tion of this aerial folvent. From whence it appears, 
that this mephitic air is the medium by which the 
metalline and abforbent earths contained in the pou- 
hon water are therein held in folution ; and, con- 
trary-wife, that thole earths are the medium, by 
which this air is more firmly united to the watery 
element in this compound, in which it enters as a 
6 principal 
