ACIDS. 13 
flame, and suffocating all animals that are immersed in. 
it. This gas, which was formerly called by chemists 
Jixed air, is about twice the weight of common air. In 
combination with lime it forms chalk, marble, and lime- 
stone ; and it constitutes part of several other mineral 
substances, which are thence denominated carbonats. 
27. Fluoric Acid is a gas of very singular nature, 
which is held in combination with lime, in the Derby- 
shire or fluor spar (194) : and may be separated from it 
by pouring sulphuric acid, or spirit of vitriol (24), upon 
powdered spar, in a leaden vessel called a retort, 
and applying to it a gentle heat. The salts formed by 
fluoric acid have the name ofjluats. 
28. The Boracic is a peculiar kind of acid, which, in 
combination with soda (200), forms the substance that 
we import from the East Indies under the name of 
borax (204). When extracted from borax this acid does 
not assume the form of a fluid, but appears in thin six- 
sided scales or flakes, of white colour, which adhere 
slightly together, and feel somewhat greasy in handling. 
To the taste it is at first sour, then bitterish ; and at last 
it leaves an agreeable sweetness on the palate. 
29. Muriatic Acid is a gas formed by the combina- 
tion of oxygen (21) with some base that is not yet 
known. It is an invisible and elastic fluid, which, in 
mechanical properties, resembles common air, and has 
a pungent and very peculiar smell. This gas unites 
with alkalies (42), earths (31), and the oxides (21) of 
metals ; and with them forms the compounds called 
muriats, of which common salt, or muriat of soda (202), 
is one of the principal. The liquid muriatic acid, or 
muriatic acid gas combined with water, is frequently 
denominated spirit of salt (202). 
