146 



CHEMISTRY. 



also been used as a fire extinguisher. For example, a Mr. 

 Gurney, in the case of a fire which nad been burning for a 

 long time in a coal-mine in Scotland, contrived to generate 

 a large quantity of carbonic anhydride, so that it should 

 flow to the spot where the fire was raging, and thus extin- 

 guished it. Here water could not be made to reach the 



to 



fire, but the gas went to it without any difficulty. 



188. Oxyhydrogen Blow-pipe. When a jet of hydrogen 

 gas is lighted, and a jet of oxygen is made to mingle with 

 it, the union of the two gases produces the greatest heat 

 known, with the exception of that which is produced by the 

 galvanic battery. The sole product of this energetic com- 

 bustion is water, the grand extinguisher of combustion. In 

 Fig. 61 is represented an extemporaneous contrivance for 



Fig. 61. 



burning these gases. The oxygen is contained in the bag, 

 which has a weight upon it to press the gas out through the 

 pipe. At the same time hydrogen gas is coming up from 

 the bottle below through another pipe. Here you have the 

 essentials of the blow-pipe invented by Dr. Hare, of Phila- 



