ACETYLENE. 787 



forms an explosive mixture, as it does also when mixed in certain 

 proportions with air ; but when burned through a very small tip 

 and under slight pressure, or when mixed with coal gas or air in 

 proper proportions, an exceedingly brilliant and highly luminous 

 flame is produced. Acetylene is poisonous, combining with the 

 haemoglobin of the blood, to the exclusion of oxygen, to form a 

 compound similar to that yielded by carbon monoxide. Moissan, 

 however, reports that when prepared from pure calcium carbide, 

 and after being purified by liquefaction, it has an ethereal odor, 

 and can be breathed in small quantities without evil effects. Re- 

 garding its explosiveness Mr. J. M. Crafts says : " Experiments, 

 using a two-inch gas pipe as a cannon, show that from five to six 

 per cent of acetylene mixed with air forms an explosive mixture. 

 . . . About ten per cent of water gas is necessary before an explo- 

 sive mixture with air is formed." Explosive mixtures in the air 

 of a room would be produced by much smaller percentages than 

 these. Lechattelier gives 2*8 per cent acetylene mixed with air 

 as an explosive compound. So far as its poisonous qualities are 

 concerned, acetylene seems to have a little the advantage of water 

 gas; the poisonous principle of the latter is carbon monoxide, 

 whose combination with the blood is somewhat more energetic 

 than that of acetylene, and which has no odor to serve as a warn- 

 ing in case of a leak, as has acetylene. Acetylene is, however, 

 more prone to form explosive mixtures. This is due to the fact 

 that in the combination of carbon and hydrogen to form acety- 

 lene 61'100 units of heat are absorbed. Thus the heating power 

 of a cubic foot of acetylene is sufficient to raise 407 kilogrammes 

 (a kilogramme = 2'2 pounds) of water 1 C. The combustion of 

 the same amounts of uncombined carbon and hydrogen as are 

 present in a cubic foot of acetylene will raise only 336'5 kilo- 

 grammes of water to 1 C, leaving a difference in favor of acety- 

 lene of 70 # 5 heat units the unit being the amount of heat required 

 to raise the temperature of- one kilogramme of water 1 C. 



Acetylene is one of the important bodies, much used by the 

 chemist in the synthesis of organic compounds. It is also reported 

 to be of value in polariscope work, permitting the reading of solu- 

 tions so highly colored as to be opaque to the ordinary sources 

 of light. Some interesting experiments with the gas in abnormal 

 physical states were recently performed by J. J. Suckert, during 

 a lecture before the Franklin Institute. A tube of liquefied acety- 

 lene was cooled to 28 F., and then the pressure removed. 

 Rapid evaporation took place, and a portion of the liquid gas was 

 solidified into a snowlike mass whose temperature was found 

 to be 118 F. A part of this snow placed on some mercury 

 in a saucer soon froze the latter, and another portion, on being 

 dropped into water, upon which it floated, gave off acetylene 



