RESEARCHES IN ELECTRO-CHEMISTRY. 211 
in making use of that fluid, the disengagement of the cdorifer- 
ous principle is either suddenly stopped or does not take place 
at all. In such cases, the surface of the positive gold or platina- 
electrode is not pure, ?. e. it is covered with some foreign sub- 
stance; and to cause the reappearance of the peculiar smell, it 
is necessary to clean that electrode, which, by my experience, is 
best done by washing it first with pure muriatic acid, and after- 
wards with distilled water. 
5. If some pinches of powdered charcoal, iron-, tin-, zinc-, or 
lead-filings, or of powdered antimony, bismuth, and arsenic, or 
some drops of mercury are thrown into a bottle containing the 
odoriferous principle (mixed with oxygen), the peculiar smell 
disappears almost instantaneously. Iron and charcoal seem, 
however, to act more rapidly than the other substances men- 
tioned do; gold and platina, when strongly heated, also destroy 
the smell. Small quantities of nitrous acid and aqueous solu- 
tions of proto-chloride of iron, sulphate of protoxide of iron, 
and proto-chloride of tin, being put into a vessel containing 
our peculiar principle, do likewise instantaneously annihilate 
the phosphorus smell. 
6. A gold, or platina plate, after having been kept only for a 
few moments within a vessel containing the odoriferous prin- 
ciple (mixed with oxygen), appears to be negatively polarized. 
To excite that polar state in the metals mentioned, it is a con- 
dition, sine gua non, 
(a) That the surface of the plate of either metal be abso- 
lutely clean and entirely free from moisture. 
(b) That the temperature of the metal be comparatively low. 
Heated gold or platina do not assume the negative polar con- 
dition. The current produced by such a polarized metal is of 
so short a duration, that it may be considered as instantaneous. 
Among the metals more readily oxidable than gold and platina, 
it is only silver and copper that are rendered negative by being 
put into an atmosphere of the odoriferous principle; but the 
degree of polarity acquired by these metals is exceedingly 
slight. 
7. Gold and platina having been polarized in the manner in- 
dicated, maintain their peculiar condition for some length of 
time when placed in common air. I have found plates which 
had been exposed to the atmosphere, at least for a couple of 
hours, still perceptibly negative. 
8. A polarized stripe of gold or platina loses, almost instan- 
taneously, its negative condition, when plunged into an atmo- 
Sphere of hydrogen. If the metal is kept in hydrogen longer 
than just required for destroying its negative polarity, it as- 
P2 
