PROPERTIES OF DRY SULPHURIC ACID. 
243 
marsh miasmata, but not the smallest quantity was absorbed. 
I then had recourse to another mode; instead of hydrated sul- 
phuric acid, I took anhydrous acid, but obtained no better re- 
sults; at the same time the action of this anhydrous acid on 
bicarburetted hydrogen is very striking. There was a great 
absorption of it, decomposition, with formation of water, sulphu- 
rous acid and a deposit of charcoal. This difference of action 
affords a good character for the separation of bicarburetted from 
protocarburetted hydrogen. 
The dry acid of commerce, with which I operated, contains 
according to some chemists a certain proportion of water in 
combination with it. Surprised to find that two bodies formed 
of the same elements, should act so differently with sulphuric 
acid, I determined to examine the action of various hydrogen- 
ated substances on this same acid. 
The first of these bodies I experimented on was phosphu- 
retted hydrogen, with which I obtained some singular results. 
Having introduced perphosphuretted hydrogen into a bell 
glass over mercury, and placed in it a vial containing dry sul- 
phuric acid, yellow fumes were formed which were gradually 
deposited on the sides of the vessel. The next day this yel- 
low powder was transformed into violet coloured drops, and 
the vial contained an indigo blue fluid. The perphosphuretted 
hydrogen had assumed the form of protophosphuretted hy- 
drogen. 
I endeavoured to reproduce this peculiar compound by 
heating phosphorus in both dry and moist sulphurous acid, 
but without success. Having placed phosphorus in contact 
with dry sulphuric acid, inflammation took place in a short time, 
with the formation of sulphurous and phosphoric acids. I am, 
however, inclined to believe that the blue compound did not 
contain hydrogen. 
Arseniated hydrogen was decomposed; and a deposition of 
arsenic ensued, which was transformed into arsenic acid, 
whilst at the same time there was a corresponding solution 
of sulphurous acid. I did not operate on selenuretted, &c. &c. 
