254 Mr. Pepys’ Account of a new Eudiometer. 
If the experiment is made hastily, the impregnated solution 
loses a portion of its nitrous gas, which must be again absorb- 
ed by a solution of green sulphate of iron. 
For ascertaining the purity of nitrous gas, the bottle maybe 
charged with the solution of green sulphate or muriate of iron. 
For carbonic acid gas, with lime or barytic water. 
For oxygene gas, with the solution of green sulphate of iron 
impregnated with nitrous gas. 
For sulphurated hydrogene gas, a solution of nitrate of 
silver was put in the elastic bottle, and sulphurated hydrogene 
gas-f into the graduated measure. Upon the first injection, the 
solution took a black ff Occident appearance, and a considerable 
portion of the gas was absorbed. After repeating the process 
as before mentioned, the residuum was — 
The instrument may be likewise generally applied to the 
analysis of mixed gases. 
I have been able, completely to separate the carbonic acid gas 
from the sulphurated hydrogene, by a solution of the nitrate 
of silver, or of mercury employed hot. The carbonic acid gas 
is expanded in this process, but on standing over mercury it 
returns to its original volume. The sulphurated hydrogene, 
in this instance, is taken up by the metallic nitrate. It should 
be here observed that the acetite of lead must not be used, as 
the carbonic acid gas, even at a high temperature, decomposes 
it, forming carbonate of lead. 
The propriety of using the solutions hot, will be seen, 
* Obtained from oxymuriate of potash by heat. 
f Obtained from sulphuret of potash by diluted muriatic acid, and collected and 
preserved with the greatest care. 
