of Sea Water, &c. 4* 
continued ftream of air from the lungs, no pre¬ 
cipitation nor cloudinefs enfued, as in the cafe of 
lime water. 
It remained to fee, whether the precipitation of 
the magnefian earth, from its acid, had been ef- 
fe&ed. Under fome circumftances, it has been 
proved, by the very ingenious- Dr. Black, that 
magnefia will precipitate calcareous earth from 
acids. As, for inftance, if mild magnefia be 
thrown into a folution of calcareous earth, in 
marine or nitrous acid, the calcareous earth will 
be precipitated; the fum of the attraflion 
between this earth and fixed air, and between 
the magnefia and the acid, being greater than 
thofe which fubfifted between the magnefia and 
the air, and between the calcareous earth and 
the acid. But, if cauftic calcareous earth be 
added to a folution of magnefia in thofe acids, 
its affinity to the acid is, in this ftate, increafed, 
no fixed air attradls it, and it precipitates the 
magnefia. 
EXPERIMENT IV. 
To fome of the fea water, which had been kept 
as a ftandard, fome lime water was added, and a 
turbidnefs immediately took place, fucceeded by 
a copious precipitation. This, at firft, con¬ 
vinced an ingenious Member of this Society, 
Dr. Eafon, who happened to be prefent, and my- 
felf, that we had difcovered the manner in which 
the 
