21 

 RELATIVE AMOUNTS OF AIR USED. 



The amount of air consumed by different illuminants has 

 recently received considerable attention and the subject is of 

 great importance, for houses are not as a rule, too well ventilated. 

 The fuels are of such a nature that the relative amount of air 

 consumed per pound or per thousand candle power hours, as 

 shown by our tests, may be calculated quite accurately. Gasoline 

 is made up of several slightly different oils ; and different gaso- 

 lines may differ considerably in density, etc., but they differ only 

 slightly in the amount of air consumed per pound (not more than 

 2% from lightest to heaviest gasoline) and vary in a like manner 

 in the amount of heat given off. Therefore, for any gasoline the 

 amount of air consumed per B. T. U. will not vary more than 

 i%. With alcohol the variation is greater. Wood alcohol re- 

 quires about 72% of the amount of air required per pound for 

 grain alcohol, but generates about 77% as much heat per pound 

 as grain alcohol, therefore the amount of air used per B. T. U. 

 is for wood alcohol only 93% of same amount for grain alcohol. 

 As the ingredients of denatured alcohol, as specified by the Rules 

 and Regulations governing the denaturing of alcohol, are one 

 hundred parts grain alcohol, ten parts wood alcohol and one-half 

 of one part benzine, the amount of air required for the combus- 

 tion of the same may be calculated very closely. The amount of 

 air required for kerosene will also be included in the table. 



SAFETY. 



The relative danger from fire connected with the use of these 

 two fuels may be considered in two ways : ( i ) The flash point or 

 temperature at which the fuel vaporizes sufficiently to form an 

 explosive mixture at a certain distance from the exposed surface, 

 (2) the relative difficulty of extinguishing the flame of either 

 while burning. 



Flash Point. The flash point is determined by various meth- 

 ods, but perhaps the method most widely used in the United 

 States is the one specified by the Iowa State Board of Health, and 

 which was followed in the tests upon these fuels. The flash point 

 as determined by these rules is the lowest temperature at which 

 sufficient vapor is given off to be ignited by a small flame, whose 

 greatest dimension is less than ^J inch, passed over the surface of 

 the oil at a distance of ^ inch. The lowest flash point allowed 

 by the State Board of Health for illuminating oils burned from 

 the exposed end of a wick is 105 degrees F. 



