36 C. G. Gmelin’s Observations cm the Producticm cf 
trace of iron and magnesia was precipitated. The filtrated so- 
lution was then precipitated by carbonate of ammonia ; the pre- 
cipitate thoroughly washed, was burnt in a platina crucible, and 
made perfectly caustic in the manner above described. 
Bwt even this perfectly pure lime had a rough surface, and 
rendered the metal negatively electrified, though not intensely. 
When this lime was finely powdered in a hot porphyry mortar, 
and again heated in a platina crucible, and cooled, the zinc plate 
assumed constantly an intense positive electricity. Even after 
several weeks, during which time the lime was kept in a well 
closed bottle, the metal became positively electrified by its con- 
tact with the lime. 
It seems to follow from these experiments, that the species of 
electricity, which is evolved, does not depend upon the chemical 
nature of the substance which is touched, but rather upon its 
physical constitution. 
Caustic strontia^ likewise, obtained by igniting pure nitrate of 
strontia, rendered the metal, positively electrified, though weak- 
ly, when it had been finely powdered, I tried also caustic po- 
tash and soda, but without a satisfactory result. 
Yttria^ purified from the oxide of cerium, according to the 
method of Berzelius, imparted to the metal such an intense 
positive electricity, even when touched on a very small , surface, 
(the diameter of the zinc plate was Gnly=:l inch, 7J lin. Par.), 
that the gold leaf touched the pile by a single contact. 
Beryllia^ on the contrary, imparted to the metal, under all 
^circumstances, an intense negative electricity. This circum- 
stance is the more singular, as this earth, in its external charac- 
ters, much resembles magnesia. 
By Silica^ the metal was constantly positively electrified, but 
the effect ceased soon after it had been exposed for some time to 
the air. 
Oxide ofZinc^ carefully prepared, imparted to the zinc plate, 
by a single contact, a very intense positive electricity. 
Oxide of Cerium^ prepared according to the method of LaUt 
GiER, gave the same result. Crystallised and fused boracic acid 
constantly imparted to the metal a positive electricity. 
’ Vitrified phosphoric acid, prepared from phosphorus by ni- 
tric acid, gave no result. When ignited in a platina crucible to 
red heat, and tjien cooled, it shewed no electricity whatever, by 
