236 



CHEMISTRY OF FARM PRACTICE 



stream of oxygen, the 

 temperature obtained is 

 remarkably high. Such 

 a flame will eat its way 

 through a six-inch steel 

 shaft in less than one 

 minute. The steel frames 

 of modern buildings may 

 be rapidly taken apart 

 by this flame. 



186. Fire Extinguish- 

 ers. Fire extinguishers 

 are effective means of 

 extinguishing a fire be- 

 fore it gains headway. 

 The presence of such a 

 contrivance may prevent 

 a disastrous conflagration 

 and will surely pay for 

 itself in the peace of 

 mind of the farmer and 

 his family. A convenient 

 form shown in Fig. 76 

 consists of a heavy metal 

 cylindrical container 

 made to withstand a 

 pressure of 350 pounds 

 per square inch. The 

 charge consists of a sat- 

 urated water solution of 

 1^ pounds of sodium bi- 

 carbonate (cooking soda, 

 NaCHO 3 ), with which 



, the cylinder is filled to 

 FIG. 76. Fire Extinguisher. (Figs. 76 



and 77, by permission of Mr. James the mark and : flmd 

 C. Goddard, Philadelphia.) ounces of sulphuric acid 



