22 THE DISCOVERY OF ARGON AND HELIUM. 



accurate scientific work than had been done by others ; he merely 

 repeated other people's work on the density of gases, because he 

 wished to get more accurate determinations, in order that from 

 those data other data might be obtained. 



I think that probably the discovery of argon and helium, 

 although at present they are of no commercial use — and I may say 

 that people often ask me what is the use of argon and helium, but 

 as it is difficult to answer such questions, I do not try — from a 

 scientific point of view, helium probably will be of the very 

 greatest use. It is a gas which has the most peculiar properties. 

 It is a gas which we call monatomic — that is to say, its atoms are 

 the same as its molecules ; the molecule and the atom are identi- 

 cal. Again, the electric conductivity of helium is very much 

 greater at ordinary pressure than that of any other gas that is 

 known. (Several experiments were here shown to prove this, the 

 electric spark traversing a helium tube in preference to one of air 

 or hydrogen, or passing through a longer distance.) Helium is 

 ten times as good a conductor of electricity as ordinary air. 

 Hydrogen up to the discovery of helium was the best conductor, 

 but it is inferior to helium. Another curious point about it is that 

 it is extremely light, and diffuses through a porous septum much 

 more rapidly than it has any business to do. It diffuses in a per- 

 fectly abnormal way. Therefore I think this gas ought to be very 

 useful to the physicists. They often talk about a perfect gas, and 

 now I think they have it, and I hope they will be able to make 

 something out of it. Chemists have done much with it, and now 

 it is the turn of the physicists. 



I have now taken up enough of your time, and hope I have 

 been able to make myself sufficiently plain, and that you now 

 know a little about the discovery of these two gases, argon and 

 helium. 



To Catch Earthworms. — According to Nature^ earthworms 

 may be obtained in any quantity without the labour of digging by 

 watering the ground with a solution of sulphate of copper of a 

 strength of i per cent. This will bring the worms to the surface 

 almost immediately. Soap-suds are said to produce the same effect. 



