GAS, AIR 



537 





vapour taken up by a given volume of air at certain temperatures. The following 

 tobies show this : 



Boiling points of light petroleum spirit of different specific gravity. 



Specific Gravity Boiling Point 



0-600 4 deg. 0. 



0-628 30 



0-669 68 



0-699 92 



0-726 118 



0-741 136 



0-757 160 



Table of maximum vapour-tension of petroleum spirit of a Sp. Gr. -650 at 



different temperatures. 



Temperature. Vapour-tension. 



-10 deg C. (14 deg F.) 43-5 mm. 



(32 ) 81-0 



+ 10 (50 ,) 132-0 



15 (60 ,) 167'0 



20 (68 , ) 203-0 



40 (104 , ) 301-8 



Table of percentage of vapour of petroleum spirit of a Sp. Gr. "650 present in 



air or other medium at different temperatures. 

 Temperature. Percentage. 



-10 deg. C. (14 deg. F.) . . . "J ' : - :.-' . 5-7 



, (32 , ) 107 



10 , (50 ,) 17'5 



15 , (60 ,) 22-0 



20 , (68 , ) 27-0 



40 , (104 , ) 39-0 



Now for an ' air-gas ' scheme to be successful, the air must hold in solution a 

 sufficient quantity of vapour to confer upon it inflammability and luminosity. 



The liquid hydrocarbons, which at present are almost exclusively proposed to be 

 employed for the purposes of carburation, are the light oils which form the first 

 distillate in the preparation of paraffin oil from the crude American mineral oil. 

 As this light oil is too volatile and inflammable to be burned in any sort of lamp at 

 present in use, and no other commercial application has been discovered, very large 

 quantities of it are disposed of as an entirely waste product, obtainable at a small 

 cost. 



The illuminating power of 'air-gas' when first obtained is very high, as high 

 indeed as 30 candles, although this statement requires a slight qualification, as the 

 illuminating power of the flame is not erpressed by it, but only the fact that if it 

 were possible (which it is not) to burn the gas at the rate required by the photometric 

 test viz. five cubic feet per hour, this illuminating power would be obtained, it being 

 a fact that a very much smaller amount of air-gas can be burned from the ordinary 

 argand burner, or from a batswing, to obtain the same rise of flame than in the case 

 of coal-gas ; this effect is no doubt due to the greater density of ' air-gas.' It may be 

 mentioned that these air-gases do not burn well under pressure, and hence are only 

 suited to burners which afford exceedingly free passage to the issuing gas, such as 

 argands, there being a tendency with burners of the batswing and fishtail class for the 

 air and vapour to separate, possibly explainable by the more rapid transpiration of the 

 lighter substance through a narrow opening. 



Mr. J. F. G. Kromschroder has spent nearly fourteen years in the endeavour to 

 effect the mixture of common air with the hydrocarbonous vapours, so as to produce 

 an ' air-gas ' suitable for the illumination of small towns or dwelling-houses. He 

 claims to have succeeded in his design, and he is probably the first man who has 

 lighted a whole town upon a system of gas illumination which excludes the use of 

 coal Great Marlow in Buckinghamshire having been lighted by him with his air-gas. 

 Mr. Kromschroder first applied his method to lighting the Battersea Water- works, 

 and for five months he kept 104 burners supplied at a cost below that of ordinary gas. 

 Farther, a quantity of his hydrocarbonised air was there stored over water for nearly 

 four months, and at the end of that time it was said to be a far better illuminator 

 than when first prepared, but this can scarcely be correct. 



The experiments made at Great Marlow have been thus described : 



