in the Coal-Mines of Germany. 



381 



I employed, as is evident, wire-gauzes of much larger aper- 

 tures than are usual in coal-mines, for I had in view to find 

 the maximum at which they are not permeable to flame. 



For these thirty cylinders of wire-gauze five lamps were 

 made, the size of which accorded with that of the cylinders. 

 The forms of these lamps were in general like those con- 

 structed originally by Sir Humphrey Davy himself, but the 

 cages made of platinum wire were wanting. 



I shall not dwell on the description of the individual expe- 

 riments. It is sufficient to ascertain the cylinders which, 

 under all circumstances, have prevented the communication 

 of explosion. Prior to these experiments, I had experi- 

 mented as to whether an explosion in the apparatus would 

 be dangerous to myself and my assistants, but this was not 

 the case. After each experiment, all holes of the apparatus 

 were opened in order to remove the impure air, and it was 

 only after a new accumulation of inflammable gas, that a fresh 

 experiment was commenced. 



There is still a circumstance for consideration. As the in- 

 flammable gas, penetrating through the wire-gauze, is partly 

 burning, the more of it will burn the greater the diameter 

 of the cylinder. Now, the circulation of the inflammable 

 gas taking place during the different experiments in the 

 Bame proportion, on applying the larger cylinder, a greater 

 quantity of gasmustbe consumed than on applyingthe less ones. 

 This was the reason that, on using the cylinders of twenty- 



VOL. XXX. KO. LX. — APRIL 1841. nb 



