WAT 
evaporated, left no sensible sediment. It 
seemed to be pure water. In another ex- 
periment, he exploded, in a j;lass globej 
19,500 grain measures of oxygen ga.s, and 
37,000 of hydrogen gas, by means of the 
electric spark. The result of the experi- 
ment was thirty grains of water, which con- 
tained a small quantity of nitric acid. The 
experiments of Mr. Cavendish were made 
in the year 1781, and they are undoubtedly 
conclusive with regard to the composition 
of water. It would appear that Mr. Watt 
entei tained the same ideas on this subject. 
When he was informed by Dr. Priestley of 
the result of these experiments, he ob- 
serves, ‘‘ Let ns consider what obviously 
happens m the deflagration of hydrogen and 
oxygen gases. These tw'o kinds of air 
unite with violence, they become red hot, 
and when cooling totally disappear. When 
the vessel is cooled, a quantity of water is 
found in it equal to the weight of the air 
employed. The water is then the only 
remaining product of the process; and wa- 
ter, light, and heat are all the products, un- 
less there be some other matter set free, 
which escapes our sgnses. Are we not then 
authorised to conclude, that water is com- 
posed, of oxygen and hydrogen gases, de- 
prived of part of their latent or elementary 
heat ; that oxygen gas is composed of wa- 
ter, deprived of its hydrogen, and united 
to elementary heat and light ; and that the 
latter are contained in it in a latent state, 
so as not to be seMsible to' the thermometer 
or to the eye. And if light be only a modi- 
fication of heat, or a circumstance attend- 
ing it, or a component part of the hydrogen 
gas, then oxygen gas is composed of water 
deprived of its hydrogen, and united to 
elementary heat.” Thus it appears that 
Mr. Watt had a just view of the compo- 
sition of water, and of the nature of the pro- 
cess by which its component parts pass to a 
liquid state from that of an elastic fluid. 
Towards the end of the same year, M. La- 
voisier had made some experiments, the 
result of which surprised him ; for the pro- 
duct pf the combustion of the oxygen and 
hydrogen gases, instead of being sulphuric 
or sulphurous acid, as he expected it, was 
pure w'ater. This led him to procure an 
apparatus, with which the experiment might 
be performed on a large scale, and with 
more accuracy and precision. Accordingly 
the experiments were performed, on the 
twent 5 '-fourth of June, 1783, in presence 
of several academicians, and also of Sir 
Charles Hlagdcn, wb.o was at that time in 
WAT 
Paris. , A similar experiment was after- 
wards performed by M. Monge, with the 
same result ; and it was repeated again by 
Lavoisier and Meusnier, on a scale so large 
as to put the matter beyond a doubt. The 
conclusion, therefore, from the whole was, 
that water is composed of oxygen and hy- 
drogen, Water exists in three different 
states; in the solid state, or state of ice, in 
the liquid, and- in the state of vapour or 
steam. Its principal properties have al- 
ready been detailed in treating of the 
effects of caloric. It assumes the solid 
form when it is cooled down to the tempe- 
rature of 32°. In this state it increases in 
bulk, by which it exerts a prodigious ex- 
pansive force, which is owing to the new 
arrangement of its particles, which assume 
a crystalline form, the crystals crossing 
each other at angles of 60° or 120°. The 
specific gravity of ice is less than that of 
water. When ice is exposed to a tempe- 
r.'itnre above 32°, it absorbs caloric, which 
then becomes latent, and is converted 
into the liquid state, or that of Water. At 
the temperature of 42W, w'ater has reached 
its maximum of density. According to the 
experiments of Lefevre Gineaux, a French 
cubic foot of distilled water, taken at its 
maximum of density, is equal to 70 pounds, 
223 grains French, equal 529,452.9492 
troy grains. An English cubic foot at the 
same temperature weighs 437,102.4946 
grains troy. By Professor Robinson’s ex- 
periments it is ascertained, that a cubic foot 
of water, at the temperature of 55”, weighs 
998.74 avoirdupois ounces, of 437.5 grains 
troy each, or about li ounce less than 1000 
avoirdupois ounces. When water is exposed 
to the temperature of 212°, it boils ; and if 
this temperature be coniinued, the whole i.s 
converted into an elastic invisible fluid, 
called vapour or steam. This, as has been 
already shown, is owing to the absorption 
of a quantity of caloric, which is necessary 
to retain it in the fluid form. In this state 
it is about 1800 times its bulk wheri in 
the state of water. This shows what an ex- 
pansive force it must exert when it is con- 
fined, and hence its application in the 
steam engine, of which it is the moving 
power. 
Waters, mineral. The complete and ac- 
curate analysis of mineral waters is one of 
the most diflicult subjects of chemical re- 
search, and requires a very extensive ac- 
quaintance with the properties and habi- 
tudes of a numerous class of substances. 
Such minuteness, however, is scarcely ever 
