186 An Analysis of two Mineral 
so abundantly diffused through the earth. Are then 
the appearances in question the result of these cir- 
cumstances? In short, are the salts muriat of man- 
ganese and oxygenated muriat of iron? In pursu- 
ance of this idea, I formed some oxygenated mu- 
riat of iron, by mixing some yellow oxyd of iron 
(the rubigo ferri of the shops) with water, and ex- 
posing it, by a proper apparatus, to the oxygenated 
muriatic acid gas. The gas readily dissolves a part 
of the exyd, a few bubbles (perhaps of carbonic 
acid) escaping during the solution. 1. The salt 
which is formed is deliquescent; colourless; of a 
pure bitter taste, without any of the sweet astrin- 
gency of the common salts of iron.* | Alkalis pre- 
cipitate a white oxyd. The mineral acids, also, de- 
compose the salt; and, at the same time, a white 
matter, of a crystalline form, precipitates, but an 
excess of acid re-dissolves the precipitate.t 2. If 
some metallic iron be digested in a solution of this 
- 
* By far the best method of making this salt, is to,put 
the rust in a saucer, and to put the mixture of manganese 
and muriatic acid, diluted to avoid a strong effervescence, 
in a cup on the same saucer; then to cover the cup with 
an inverted glass: thus the oxygenated vapour will be con- 
fined as itis slowly extricated. If distillation is used, the 
salt can be hardly made free from an astringent taste. 
+ The sulphuric acid does not re-dissolve the precipi- 
tate; the othersdo. Some further remarks on this subject 
will be found (x1v, 6.) - 
