THE SAFETY»LAMP. 645 
the operator upon the stop-cock of the jet, on the outside of 
the screen. G H, a tube of glass, or of brass, for the jet. 
And I, the spirit lamp for igniting the gas. 
Among the many veiy curious experiments made with the 
blow-pipe by Doctor Clarke, the following may be adduced 
as examples. Several oriental rubies being placed on char- 
coal, their fusion was so rapid that he feared they would 
Volatilize. They ran together into a bead, and remained in 
such a liquid state before the gas, that the current of it 
penetrated like a stream of air upon oil, when urged by a 
pair of bellows. The bead, when examined, was white and 
opaque ; all colour having disappeared. Being again exposed 
to the ignited gas, and taken from the charcoal by iron 
forceps, its surface was covered by a thin flaky metallic sub- 
stance, which came off on the fingers, glittering like scales 
of carburet of manganese. On being fused a third time, it 
assumed a variety of shapes, like sapphire during fusion. — 
The reduction of the oxide of tin aftbrded an easy and very- 
beautiful experiment. Wood-tin, exposed to the ignited 
gas, communicated a beautiful blue colour, like that of 
violets, to the flame. In employing a pair of iron forceps, 
as a support, the iron became covered with an oxide of tin 
of incomparable whiteness. The fusion was rapid ; and 
when the wood- tin was placed on charcoal, the metal was 
revived in a pure and malleable state. — In effecting the 
fusion and combustion of platinum, the largest drops which 
fell from the melting of platinum wire, when exposed to the 
utmost heat, weighed ten grains ; but drops of metal weigh- 
ing fourteen grains were obtained, when the current of gas 
Was diminished so as not to let the metal run otf too quickly 
from the wire. By placing several globules on a piece of 
charcoal, and suffering tire whole force of the gas to act upon 
them, the metal was made to boil, and they all ran together 
into one mass. 
THE SAFETY LAMP. 
The invention of the wire-gauze-safe-lamp, for preventing 
explosions from fire-damp, and for giving light in explosive 
atmospheres, is .due to Sir Humphrey Davy, who 
remarks that the dreadful accidents ot explosions are 
occasioned by the firing of light carburetted inflammable gas. 
