10 



In this lamp it is noticed that the small pump for lifting the alcohol 

 to start the vaporization is omitted, its place being taken by the 

 ball of asbestos saturated with alcohol, inserted at the opening F 

 as jusjt stated. 



It is evident that the amount of heat produced is to some extent 

 a measure of the illuminating value when the incandescent mantle 

 is taken into consideration. It is the high temperature which pro- 

 duces the incandescence and therefore the gas which in burning 

 gives the highest temperature, other conditions being the same, 



FIG. 7. Alcohol lamp with asbestos primer. 



would be of the most value for illumination. All of these points 

 must be considered to prevent the formation of wrong opinions con- 

 cerning the efficiency of alcohol for illumination, heating, and motive 

 power, as compared with gasolene, which is the agent most used for 

 these purposes, and which alcohol is expected to supersede. 



QUANTITY OF HEAT YIELDED IN THE COMBUSTION OP ALCOHOL. 



It has been estimated that 1 gram a of gasolene will yield on com- 

 plete combustion 11,000 calories, 6 and 1 gram of pure alcohol 7,200 

 calories. No determination of the heat of combustion of ordinary 



a 1 gram = 0.03527 ounce, or 15 grains. 



*> A calorie is the amount of heat necessary to raise 1 gram of water 1 centigrade (1.8 

 Fahrenheit). 



