ARGON. 525 



pressure at 187. Its critical and boiling points lie between those 

 of oxygen and nitrogen, nitrogen having the lowest of the three. 



Argon is four tenths heavier than nitrogen, and much more 

 soluble in water. As already stated, and as is evident from the 

 methods employed for its preparation, argon is more inert than 

 nitrogen ; so great is its chemical indifference, that all attempts 

 to bring about reactions with even the most active substances at 

 high temperatures have thus far proved abortive. It is unaf- 

 fected by phosphorus or sulphur at red heat ; sodium and potas- 

 sium may be distilled in it without loss of their metallic luster ; 

 it is unaltered by fused and red-hot caustic soda or niter ; aqua 

 regia and other wet oxidizing and chlorinating agents are entirely 

 without action ; and it resists the attack of nascent silicon and 

 boron. 



Though thus unique in its chemical inactivity, it would be 

 premature to conclude that argon may not form compounds under 

 conditions yet untried,* and that it is an absolutely " idle " and 

 useless thiug. Prof. Roberts- Austen suggests that it may possi- 

 bly play a part in certain metallurgical operations in which air is 

 largely employed. In making Bessemer steel, for instance, not 

 less than one hundred thousand cubic feet of air are blown 

 through each charge of metal for the purpose of removing the 

 carbon, silicon, phosphorus, and other impurities. In this air 

 there must be over one thousand cubic feet of argon. Now, Prof. 

 Roberts- Austen has found by experiment that the nitrogen which 

 can be pumped out of Bessemer-blown metal, and which is twice 

 the volume of the metal, contains little or no argon ; and the 

 question arises, whether the argon may not have united with the 

 iron, as nitrogen undoubtedly does, and confer upon Bessemer 

 steel some of the peculiarities which distinguish it from other 

 steel. It is, of course, possible and perhaps more likely that the 

 argon passes through the molten metal without combining with 

 it ; but the suggestion is an interesting one, and well worth ex- 

 perimental examination. 



Further, it may prove that argon is in some way taken up by 

 plants, and contributes in an important manner to their nourish- 

 ment and growth ; although the attempts to extract argon from 

 vegetable and animal substances have thus far yielded only nega- 

 tive results. As is well known, plants are unable to take nitrogen 

 directly from the air, but obtain it from nitrogenous compounds 

 which are absorbed in solution by their roots. The air is, how- 

 ever, the original source of these compounds, as well as of all 



* Berthelot announces that he has succeeded in causing argon to react with certain 

 organic compounds, especially with the vapor of benzene, by means of the silent electric 

 discharge. 



