THE GASES OF THE ATMOSPHEEE 135 



atom, and its molecular weight is therefore the same as 

 its atomic weight, namely 19*94 x 2 or 39 '88. Accord- 

 ingly the symbol A or A! is given to the element. 



The chemical inactivity of v argon was the feature of the 

 element which attracted most attention, and naturally 

 great efforts were repeatedly made to get evidence of 

 the formation of a compound by the gas. The announce- 

 ment by Berthelot of the production of a peculiar viscous 

 compound by exposing benzene vapour and argon to the 

 action of a silent electrical discharge turned out to be a 

 mistake, and there was no reason to suppose that the 

 small quantity of argon absorbed was held in any way 

 except mechanically. Ramsay held the view that " if 

 argon forms a compound it must be with some rare 

 element. It would have been discovered years ago if 

 it had formed one with any of the commoner elements." 

 On the day following the meeting at the Royal Society 

 he received from Mr. H. A. Miers (afterwards Sir Henry), 

 Keeper of the Mineral Department of the British Museum, 

 -a letter drawing his attention to the work of Hillebrand 

 {American Journal of Science (1890), xi. 384), who 

 reported the frequent presence of what he supposed to 

 be nitrogen in the natural uranates. Both Miers and 

 Ramsay believed that the mineral cleveite, one of the 

 uranates, would be found to contain a compound of argon. 

 On the 17th March, 1895, in a letter to Mr. Buchanan, 

 Ramsay refers to the gas from cleveite as follows : 



" Crookes thinks its spectrum is new, and I don't see from the 

 method of treatment how it can be anything old, except argon, 



