388 



SCIENCE. 



[N. S. Vol. III. No. 63. 



weakened by rust or neglect, the danger in 

 case of fire and the very doubtful economy 

 of the sj^stems, the summary seems un- 

 favorable to use of liquified acetylene, except 

 in places vrhere sufficient space can be had 

 to isolate the cylinders as gasoline tanks 

 are now isolated. 



It will be seen later that these cylinders 

 may be exposed to a special danger, al- 

 though a very improbable one, from the ex- 

 plosive decomposition of acetylene under 

 the impulse of a certain kind of shock. 



THE TEMPEEATDEE OF THE ACETYLENE 

 FLAME. 



When we compare acetylene and common 

 gas illumination from the point of view of 

 the products of combustion which vitiate 

 the air of a room, or of the heat which is 

 given off, the conclusions are very favorable 

 to acetylene lighting, because ten times as 

 much common gas has to be burnt to obtain 

 the same amount of light as would be given 

 by a unit measure of acetylene. The heat- 

 ing effect, however, is not in the ratio of ten 

 to one. Ten cu. ft. of Boston gas give 2.42 

 times as much heat as 1 cu. ft. of acetylene. 



Prof. Lewes* has calculated the amount 

 of carbonic acid given off by different il- 

 luminants, and finds, for an equal amount 

 of light, that coal gas gives off" six times as 

 much as acetylene, and he estimates that the 

 heat from acetylene would not be much 

 greater than from the ordinary incandescent 

 lamp. 



The true relations are for the same 

 amount of light : Heat from incandescent 

 light, 1 ; acetylene, 3 ; water gas, 9. 



Prof. Lewes says, in the same connection : 

 " The flame of acetylene, in spite of its il- 

 luminating value, is a distinctlj' cool flame, 

 and in experiments which I have made by 

 means of the Lechatelier thermo-couple, the 

 highest temperature in any part of the flame 

 is a trace under 1,000° Cent. While coal 



* A paper read before the Society of Arts, London. 



gas, burning in the same way in a flat-flame 

 burner, the temperature rises as high as 

 1,360 Cent." 



It is not an advantage, but a disad- 

 vantage, that the fishtail acetylene flame 

 should be cool. Its temperature is lowered 

 by the excessive contact with air requu-ed 

 for complete combustion, and, if the flame 

 could be made hotter, more light could be 

 obtained for the same quantity of heat. It 

 is scarcely necessary to add that the temper- 

 ature of a flame has nothing to do with the 

 heat of combustion. Phosphorus or so- 

 dium can be burnt at the ordinary temper- 

 ature, or at a red heat, and the heat of com- 

 bustion is the same at either temperature, 

 provided the products of combustion are the 

 same. 



Lechatelier,"* one of the best authorities 

 upon such a subject, does not appear to have 

 measured the temperature of the acetylene 

 flame with his pyrometer, and, in fact, such 

 measurements are very difficult ; but he has 

 calculated that acetjdene, burned with air, 

 may reach a temperature of 2100° to 2400° 

 Centigrade, and, burned with oxygen, 4000°. 



It is easy to melt platinum in a common 

 air blowpipe flame fed with acetylene, but 

 the platinum appears to first form a carbide. 



Acetylene, notwithstanding its high cost, 

 may find a restricted use in the laboratory 

 in air or oxj^gen blast furnaces ; it will un- 

 doubtedly give a higher temperature than 

 gas or hydrogen. 



The preceding description has continually 

 held in view the utilitarian side of the ques- 

 tion, and it has been thought simpler to 

 enumerate the items in favor of the eco- 

 nomical use of acetylene as compared with 

 gas and not to extend the comparison to 

 other forms of illumination, but the follow- 

 ing table mostly taken from the most recent 

 bookf on the subject gives the means of 



* Comptes Rendus, December 30, 1895. 

 t Julius Swoboda : Petroleum Industrie. Tiib- 

 iugen, 1895. 



