453 
on the saline contents of sea-water. 
the least acted upon, nor was any smell of nitric acid per- 
ceived ; but on adding the smallest quantity of nitre to the 
same mixture, the gold was dissolved, and the smell of aqua 
regia was instantly perceived.* 
A portion of the said bittern was next examined by ap- 
propriate re-agents, with a view to detect any minute quantity 
of earths or metals, especially alumina, silica, iron and copper, 
which former inquirers might have overlooked ; but I could 
find no other earth except magnesia : and to my surprise, I 
did not find in the bittern the least particle of lime ; which 
proves that sea-water contains no muriate of lime, as had 
been generally supposed. I was equally unsuccessful in my 
attempts to detect iron or copper, by the most delicate tests. 
In fact, neither alkalies, nor alkaline carbonates, precipitated 
any other substance from the bittern of sea-water, except 
magnesia. 
The deposit obtained at Portsmouth during the early 
period of the concentration of the water, being analyzed, I 
found it to consist of selenite, mixed with a little muriate of 
soda, and a portion of carbonate of lime. The presence of 
this last subtance in sea-water, in a state of perfect solution, 
being, I believe, a new fact, I neglected no means of establish- 
ing it with certainty, an object which was accomplished with- 
out difficulty .-f 
Carbonate of magnesia having been supposed by some 
* For this easy and elegant process for detecting nitric acid, a point attended 
with difficulty, I am indebted to Dr. Wollaston. 
f The deposit was treated with acetic acid, which occasioned an effervescence. 
The clear liquor being then decanted off, and evaporated to dryness, and alcohol 
added, acetate of lime was found in the filtered alcoholic liquor. 
