128 
the mixed gases as they burst at* the surface of the water 
in the jar. This white cloud remained permanent, and its 
unexpected appearance gave rise to many conjectures. 
When the jar became filled with the oxygen and hydrogen, 
it was removed from the shelf for the purpose of refilling 
with water, in order to repeat the experiment. As the 
gases were displaced from the jar, we became aware of the 
presence of a powerful odour, so pungent as to produce 
coughing. This was a second surprise, and it led to 
considerable discussion. The prevailing opinion seemed to 
be that some impurity in the sulphuric acid, used in the 
voltameter, had caused the white cloud and the odour. On 
one point we were all agreed— the odour was identical with 
that produced during the excitement of a frictional electrical 
machine, and the novel phenomena we had witnessed were 
admitted to be worthy of investigation. On repeating the 
experiment a second time similar results were obtained, and 
the room was filled with the electrical odour ; being mani- 
pulator, I probably inhaled more of this odour than the 
rest of the company, and my throaT was in a state of 
irritation for several days. I constructed another battery 
of similar power to that already named, and repeated the 
experiment at my own house, taking the precaution to have 
carefully-prepared sulphuric acid in the voltameter. The 
white cloud and odour were produced just as in the first 
experiments. 
It became clear, therefore, that impurity in the sulphuric 
acid was not the origin of either cloud or odour. I filled 
several bottles with these odorous gases, and tried some 
experiments, such as the solubility of the odorous substance 
in water, its alkaline and acid properties, &c. These experi- 
ments were named to many scientific friends, one of them, 
the late Dr. Brett, then a chemist of repute, a relative of 
Dr. Golding Bird, of London. Dr. Brett offered to join me 
in investigating the properties of this peculiar odorous body, 
