SULPHUROUS. 
cisely the same with that exhaled by sulphur burning 
with a blue flame: sulphur, by such a combustion, be 
ing totally converted into sulphurous acid. Its speci 
fic gravity, according to Bergman, 1s c.00246*; ac 
cording to Lavoisier, o.00251f. It is therefore some 
what more than twice as heavy as air. One hundred 
cubic inches of it weigh nearly 63 grains. 
Like sulphuric acid, its component parts are sulphur 
and oxygen; but the proportion of its oxygen is small 
er. According to Fourcroy, it is composed of 
85 sulphur 
15 oxygen 
100t 
It is probably a compound of sulphuric acid and sul 
phur: For it may be formed by heating together sul 
phuric acid and sulphur ; and it is decomposed by al 
most all substances which act upon sulphuric acid, 
which should not be the case if sulphuric acid were a 
compound of sulphurous acid and oxygen, as is com 
monly supposed. 
This acid reddens vegetable blues, and gradually de 
stroys the greater number of them. It exercises this 
power on a great variety of vegetable and animal co 
lours. Hence the use of the fumes of sulphur in bleach 
ing wool and in whitening linen stained by means of 
fruits. 
Dr Priestley discovered, that when a strong heat is 
applied to this acid in close vessels, a quantity of sul 
phur is precipitated, and the acid is converted into sul 
* Bergman, i. 343. 
t Lavoisier's Cbem. Appendix. 
1 Foureroy, ü. 74. 
B4 
23 
Chap. IV. 
Action of 
heat,