453 
THE RESULT OF THOMSON’S EXPERIMENT. 
This saline matter is in small scales. It 
has an excessively acid taste. When exposed 
to the air it gradually runs into a liquid, 
which is pure sulphuric acid. When thrown 
into water a violent effervescence takes place, 
nitrous gas is given off in abundance, and a 
solution of sulphuric acid remains. 1'his 
saline matter has been repeatedly examined. 
Davy considered it to be a compound of 
nitric acid and sulphurous acid. Dr. Henry 
examined it some years ago, and concluded 
from his experiments that it is a compound of 
hyponitrous acid and sulphurous acid. 
By the kindness of Mr, Tennant I have 
had repeated opportunities of examining this 
matter in a state of great purity. 1 have 
subjected it to various experiments, and have 
been led to form a different opinion from that 
entertained by Dr. Henry of its composition. 
How far the experiments which I shall detail 
warrant that opinion, I leave to practical 
chemists to determine. The analysis is not 
quite satisfactory, because we cannot deter- 
mine experimentally the quantity of water 
present. 
1 . When a quantity of the saline matter 
is mixed with water in a retort, a strong 
effervescence takes place, and nitrous gas 
escapes in torrents. The whole dissolves in 
the water, with the exception of a small 
quantity of white matter, the weight of 
which varies in different specimens. This 
white matter when dried is a tasteless 
powder, insoluble in water. When heated it 
takes fire, and burns with a blue flame, while 
some sulphur sublimes. What remains is 
pure sulphate of lead. These phenomena 
characterize lead sulphite of lead. Hence, 
it is evident, that the saline matter from 
the leaden chambers contains sulphite 
of lead. From 550 grains of saline mat- 
ter 1 obtained 8*43 grains of sulphite of 
lead, or about 1.53 per cent. In another ex- 
periment ICO grains of the saline matter 
yielded 1’4 grains of sulphite of lead, or 
somewhat under one per cent. These two 
experiments show the two extremes ; in all 
the others the quantity was intermediate. 
2. 58 grains of the saline matter were 
heated in a small retort. The solid matter 
became partially liquid and fumes of nitrous 
acid made their appearance. On increasing 
the heat an effervescence took place, and gas 
passed rapidly. It was yellow like nitric acid 
fumes, and like that acid acted on mercury, 
which prevented me from collecting th^^gas. 
When the effervescence stopped, a colourless 
liquid remained with a small deposit of sul- 
phite of lead at the bottom of the retort. 
This liquid was colourless, but it effervesced 
violently giving out nitrous fumes w’^hen 
mixed with water. It remained, therefore, 
the same mixture or compound as the original 
saline matter. 
3. When the saline matter is triturated 
with carbonate of ammonia, combination takes 
place without any sensible decomposition. 
4. It was triturated with a quantity of bi- 
carbonate of potash in powder, which from pre- 
vious experiments was judged capable of just 
saturating the uncombined acids. Ftimes of 
nitric acids were given off till the w'hole be- 
came quite dry. The trituration being 
continued, the mixture softened into a white 
paste, which was left exposed to the air for 
some hours. On examining this residue, it 
was found to consist chiefly of a mixture of 
sulphate of potash and carbonate of potash 
with a very little nitrate ; the nitric acid had 
been almost all dissipated during the tritu- 
ration. 
5, 160 grains of the dry saline matter were 
put into a retort mixed with water and the 
deutoxide of azote collected as it was extri- 
cated. The quantity of this gas evolved, 
supposing the thermometer at oO'’ and the 
barometer at 30 inches, was 59 35 cubic 
inches. 
The liquid in the retort being freed from 
the sulphite of lead, was found to be a solu- 
tion of sulphuric acid in water, without any 
trace of nitric or sulphurous acid. This sul- 
phuric acid being obtained partly in the state 
of sulphate of soda, and partly of sulphate 
of barytes, amounted to 132.24 grains= 
105*79 grains of sulphurous acid. 
The weight of the nitrous gas obtained was 
1917 equivalent to 34 5 grains of nitric acid. 
The constituents obtained were. 
Sulphurous acid 105*79 
Nitric acid 34*50 
Sulphite of lead 1-40 
Hrrg 
Loss 18‘3i 
160 - 
This loss must be water. The constitu- 
ents then are very nearly 
1 atom nitric acid 6*75 
5 atoms sulphurous acid. 20 00 
3 atomswater 3*375 
30*125 
That the acid present is nitric and not 
hyponitrous I infer from the phenomena of 
the distillation of the saline matter ; and 
from our knowledge of the factthat nitric acid 
is actually introduced into the leaden cham- 
bers along with sulphurous acid, and there 
being nothing present to convert it into 
hyponitrous. 
There is no evidence from the analysis that 
the whole acid of sulphur was in the state of 
sulphurous acid. I am induced from the pro- 
portions found to suspect that 2-8ihs of it was 
in the state of sulphuric acid, and 3-5ths in that 
of sulphurous acid. On that supposition it is 
easy to see how the atom of nitric acid, by 
giving out 3 atoms of oxygen, converts the 3 
atoms of sulphurous into sulphuric acid, while 
the acid thus decomposed makes its escape 
in the form of deutoxide of azote. 
The preceding analysis was repeated with 
very nearly the same result. If the supposi- 
tion of the saline matter containing 2-5ths of 
sulphuric and 3-6ths of sulphurous acid be 
