MUR 
continent. In its common form it is an 
opaque mass, and is not affected by the air, 
but its crystals are liable to deliquesce. It 
is decomposed by the snlpliuric and nitric 
acids, whicb combine with alkali ; and like- 
wise by potash, soda, barytes, and lime, 
■which unite witli the acid. By the latter of 
these decompositions ammonia is obtained 
in a state of purity ; bence, by breaking in- 
to small pieces muriate of ammonia, with 
soda, or potash, &c. and putting them to- 
gether in a phial with a glass stopple, we 
get a good smelling-bottle. This salt is 
used in many of the arts. In soldering, 
it cleans the surface of the metals to be 
united, and prevents their oxydation: in 
dying it renders several colours brighter, 
and it is not unfrequently employed in phar- 
macy and chemistry ; it consists of 
Muriatic acid 48 
Ammonia 14.9 
V/ater 37.1 
100 
MURIATIC acid, in chemistry, may be 
procured in various ways : if a retort with 
a curved tube be half tilled with well dried 
common salt, and some strong sulphuric 
acid be poured upon it, a copious efferves- 
cence takes place, and the elastic fluid ex- 
tricated appears in the form of a white va- 
pour as soon as it comes in contact with the 
atmosphere. When all the common air has 
been driven out of the retort, the subse- 
rpient portions of gas may be collected in 
the usual manner in glass jars, filled with 
mercury, and invei ted in a bath of the same 
fluid. This is muriatic acid gas ; it is trans- 
parent, colourless, and possessed of the 
same mechanical properties as common air. 
It is almost twice as heavy as common air: 
100 cubic inches of it weighs nearly 60 
grains. Its smell is pungent, and its taste 
highly acid. It is instantaneously fatal to 
animal life, and is incapable of supporting 
combustion; but if a burning taper be 
plunged into it, the flame, just before it 
goes out, may be observed to assume a 
green colour. If a little water be let into a 
jar filled with this gas, the whole gas disap- 
pears,, and the liquid, which consists of a 
.solution of muriatic gas in water, is usually 
denominated simply muriatic acid. Being 
obtained from salt, it was originally called 
“ spirit of salt,” then “ marine acid,” and 
now it is almost universally denominated 
“ muriatic acid.” Acubical inch of water,at 
tlie temperature of 60°, absorbs 515 inches 
MUR 
of muriatic acid gas, which are equivalent 
to 308 grains : hence water thus impreg- 
nated contains more than half its weight of 
muriatic acid, in tlie same stale of purity as 
when gaseous. During the absorption of 
the gas, the water becomes hot. Ice also 
absorbs this gas, and is at the same time 
liquified. The quantity of this gas absorbed 
by' water diminishes as the heat of the water 
increases, and at a boiling heat water will 
not absorb any of it : of course the gas is 
easily expelled from the liquid acid by iieat, 
and may readily be procured by heating 
the common muriatic acid of commerce. 
By this process Dr. Priestley first obtained 
it. The muriatic acid of tlie shops Is always 
yellow, owing to a small quantity of iron 
which it holds in solution. 
Muriatic acid is capable of combining 
with oxygen, and forms with it compounds, 
which have a considerable analogy to the 
compounds of azote with the same principle. 
When this acid is poured upon black oxide 
of manganese, a gas comes over, that is 
sometimes called “ dephlogisticated muria- 
tic acid,” but more generally “ oxy-mu- 
riatic acid.” It is green, has a very bad 
odour, and is readily absorbed by water. 
The constituent parts of oxy-muriatic acid 
are 
Muriatic acid 89 
Oxygen ii 
100 
When a current of oxy-muriatic acid is 
passed through water holding potash in so- 
lution, a number of flat shining crystals are 
deposited : these are denominated hyper- 
oxy-muriate of potash. They contain 
Muriatic acid 34 
Oxygen 66 
100 
It does not appear that either hydrogen 
or carbon combines with muriatic acid , but 
charcoal absorbs it abundantly. Phospbo- 
rus absorbs a little, and sulphur imbibes it 
slowly. When mixed with nitric acid, it 
forms what was formerly denominated 
“ aqua regia but is now called “ nitro-mu- 
riatic acid.’’ Muriatic acid in a state of 
gas ncutraliees putrid miasmata, and de- 
stroys their bad effects. By this tlie most 
contagious diseases are prevented from 
spreading : two parts of sulphuric acid, and 
six of common salt, heated over a spirit 
lamp, or in a hot sand batli, will give out 
the gag very plentifully. I’lie use of muria,- 
