CALAMINE. 211 
plate of zinc be applied to the upper surface of the 
tongue, and a shilling to the lower surface, and both 
metals, after a little while, be brought into contact, a 
very peculiar taste will, at that instant, be perceived. 
The same sensation will be perceived, though in a 
weaker degree, if the silver be placed at the top and 
the zinc at the bottom. 
If a silver probe be introduced high up one of the 
nostrils, and be brought into contact with a piece of 
zinc placed on the tongue, a sensation not unlike that 
of a strong flash of light will be produced in the cor- 
responding eye. A similar perception will result, both 
at the moment of contact and that of separation, if one 
of the metals be applied as high as possible between 
the gums and upper lip, and the other in a similar situ- 
ation with the under lip, or eve-n under the tongue. 
A white oxide (21) prepared from zinc, was, some 
3'ears ago, proposed as a substitute for white lead in 
house painting. This oxide is not dangerous in its 
application ; and does not become yellow when mixed 
with oil. But these advantages are counterbalanced 
by some defects, which have hitherto caused it to be 
rejected. It is lighter than white lead : does not cover 
the surface so equally, nor so well ; and is of consi- 
derably higher price. 
CALAMINE. The principal use of calamine is in the 
manufacture of brass (230) ; and the mines of Derby- 
shire, and of Limbourg in the Netherlands, supply with 
this mineral nearly all the brass works in Europe. 
After the calamine is dug out of ground, it is reduced 
to pieces not in general larger than a nut. It is then 
roasted for five or six hours, in what is called a rever- 
berating furnace. The large pieces are separated, and 
the small ones are passed through a sieve. It is 
washed; and, when dry, is ground in a mill. In this 
state it is sold. The principal demand for it is at 
Birmingham, for the different brass founderies in that 
town. 
The use of calamine in the composition of brass was 
