588 POPULAR SCIENCE MONTHLY. 



want of electric polarity. No other elements would have resisted 

 such treatment, except those of the argon group. But these are not 

 the only data from which such a conclusion can be drawn; for it was 

 found that no action takes place between argon and hydrogen, phos- 

 phorus, sulphur, tellurium, caustic soda, potassium nitrate, sodium 

 peroxide, sodium persulphide, nitro-hydrochloric acid, bromine-water 

 and many other reagents which it would be tedious to mention, all of 

 which are remarkable for their chemical activity. We may therefore 

 take it that the name 'argon,' which means 'inactive,' has been happily 

 chosen. 



In attempting to form compounds of argon, however, another 

 consideration was not lost sight of; if compounds of argon were 

 capable of existence, they ought to exist in nature ; and as in all prob- 

 ability they would be easily decomposed by heat, it ought to be pos- 

 sible to decompose them with evolution of argon, which could be 

 collected and tested. Professor Miers, in a letter which he wrote me 

 the day after an account of the fruitless attempts to cause argon to 

 combine had been given to the Koyal Society, drew my attention to 

 experiments by Dr. Hillebrand of the United States Geological Survey, 

 in course of which he obtained a gas, which he believed to be nitrogen, 

 by treating the rare mineral clevite, a substance found in felspathic 

 rocks in the south of Norway, with sulphuric acid. The chief con- 

 stituents of clevite are oxides of the rare elements uranium and 

 thorium, and of lead. The gas obtained thus, after purification from 

 nitrogen, was examined in a Pliicker tube with the spectroscope, and 

 exhibited a number of brilliant lines, of which the most remarkable 

 was one in the yellow part of the spectrum, similar in color to the 

 light given out by the glowing tube. The position of this line and of 

 others which accompany it established the identity of this gas, not with 

 argon, as was hoped, but with a supposed constituent of the sun's 

 chromosphere, first observed by M. Janssen of Paris, during an eclipse 

 which was visible in India in 1868. The late Sir Edward Frankland, 

 and Sir Norman Lockyer, who studied the spectrum of the chromo- 

 sphere, gave to the supposititious element, which they regarded as the 

 cause of these lines, the name 'helium,' a word derived from ^yjXco^^'' 

 Greek for 'the sun.' Having been placed on the track, I examined, 

 with the assistance of Dr. Collie and Dr. Travers, no fewer than 51 

 minerals; while Sir Norman Lockyer examined 46 additional ones, 

 which we had not examined; and in 19 minerals, almost all of them 

 containing uranium, helium was found. Only one gave an argon 

 spectrum, namely malacon. We also sought for argon and helium in 

 meteorites, which all give off gas on heating ; but in only one specimen, 

 a meteorite from Augusta County, Virginia, was helium found, in this 

 case accompanied by argon. All natural waters contain argon, for 



