210 REPORT—1840. 
negative one; for when the gases resulting from the electro- 
lysis of water are received in separate vessels, the smell is 
perceived only in that which contains oxygen. 
3. The odoriferous principle can be preserved in well-closed 
vessels for a great length of time, whether mixed with oxygen 
or with detonating gas. 
4. The disengagement of the smelling substance depends— 
(a) Upon the nature of the positive electrode. 
(b) Upon the chemical constitution of the electrolytic fluid, 
and 
(c) Upon the temperature of that fluid. 
With regard to the circumstance mentioned under (a), my 
experiments have shown that it is only well-cleaned gold and 
platina which are capable of disengaging the odoriferous prin- 
ciple. The more readily oxidable metals, as well as charcoal, 
do not possess that property at all. 
It is worthy of remark that iron, though acting (agreeably 
to my former experiments) like gold and platina when perform- 
ing the function of the positive electrode, does not permit the 
disengagement of the odour. 
As to the condition mentioned under (4), I have ascertained 
that the odoriferous principle is obtained from distilled or com- 
mon water when mixed with chemically pure, or with common 
sulphuric acid, with phosphoric acid, nitric acid, potash, and a 
series of oxi-salts. I could not get a trace of it from aqueous 
solutions of chlorides, bromides, iodides, fluorides, hydro- 
chloric acid, hydro-bromic acid, hydriodic acid, hydro-fluoric 
acid, sulphate of protoxide of iron. If to the fluids (above 
mentioned), which permit the disengagement of the peculiar 
smell, small quantities of nitrous acid, iron vitriol, proto- 
chloride of iron or of tin are added, not the least portion of the 
odoriferous principle will be given out, however actively water 
may be electrolysed. With regard to the aqueous solution of 
potash, I have observed the curious fact, that the smell is some- 
times disengaged from it and sometimes not, the latter case 
occurring much more frequently than the former. I do not 
know yet the cause of that anomaly. 
Concerning the influence which temperature exerts upon the 
development of the peculiar smell, I have found that a fluid 
from which the odoriferous principle is abundantly disengaged 
at a comparatively low temperature, does not yield a trace of it 
when heated near its boiling point. I must not omit to state, 
that dilute sulphuric acid is the fluid best fitted for producing 
the smelling substance, and making the experiments which this 
memoir refers to. It sometimes happens, however, that even 
