340 POPULAR SCIENCE MONTHLY. 



metric tons. These figures will justify the statement made at the 

 beginning of this article, that the new industry has found ample 

 capital. 



The statement is still current that acetylene attacks copper and 

 brass, forming an explosive compound. This is not true 1 . Exhaust- 

 ive experiments by Moissan and by Gerdes, keeping these and other 

 metals in contact with acetylene for months at a time, have shown 

 that the metals were not affected. The conditions under which the 

 explosive copper acetylide is made in laboratories can not well occur 

 in generators or gas holders. It has been said that acetylene is very 

 poisonous; the experiments of many observers, and especially those 

 of Grehant, do not confirm this statement. Grehant experimented on 

 dogs, causing them to breathe mixtures of acetylene, air, and oxygen, 

 which always contained 20.8 per cent of oxygen, this being the per- 

 centage of oxygen in pure air. By this device he was able to dis- 

 criminate between the poisoning caused by acetylene and suffocation 

 caused by insufficient oxygen. A mixture containing twenty per 

 cent acetylene inhaled for thirty-five minutes did not seem to trouble 

 the animal. A sample of the dog's arterial blood contained ten per 

 cent of acetylene. A dog which inhaled a mixture containing forty 

 per cent of acetylene died suddenly after fifty-one minutes, having in- 

 haled one hundred and twelve litres of the mixture; the arterial blood 

 contained twenty per cent acetylene. Grehant proved that acetylene 

 simply dissolves in the blood plasma, while carbon monoxide forms a 

 compound with the haemoglobin of the blood. A dog breathing a 

 similar mixture of air, oxygen, and illuminating gas containing only 

 one per cent of carbon monoxide quickly showed convulsive move- 

 ments, and died after ten minutes; its blood contained twenty-four 

 per cent of carbon monoxide. Thus acetylene, while slightly poison- 

 ous, is less poisonous than coal gas, and vastly less than water gas, 

 which contains a high percentage of carbon monoxide. 



A pressure of thirty-nine atmospheres and three quarters at 20 C. 

 converts acetylene into a liquid weighing one third as much as the 

 same volume of water, while one cubic foot of the liquid when re- 

 leased from pressure gives five hundred cubic feet of gas. 



Hitherto acetylene is used only as a source of heat or as a source 

 of light; yet with very cheap carbide it would prove useful in many 

 ways in chemical industry, and its use would have the most wide- 

 spread effect on industry and agriculture. For instance, a method 

 of making alcohol from acetylene is patented abroad, and by another 

 patented process it is proposed to make sugar from acetylene. With 

 the present prices of alcohol, sugar, and carbide, these processes have 

 no commercial value. 



Acetylene may be made from the carbide in gas works and de- 



