MODERN ALCHEMY. 145 



a similar body, thorium X. Unlike, however, uranium X, 

 the thorium X, on decaying, gives rise to a third radio- 

 active body which has been called the thorium emanation, 

 an emanation, because its discoverer Rutherford was 

 unwilling to prejudge the question as to whether it was a 

 gas. On dissolving the thorium compound in water and 

 bubbling air through it, this emanation passes away with 

 the air and floats about with it. Its presence is obvious 

 from its ray-emitting power which is intense. It is certainly 

 not finely disseminated thorium X because its rate of de- 

 cay is wholly different. It seems to be a gas. We explain 

 this to our opponent who lifts his bushy eyebrows and 

 quietly asks: "If this emanation is a gas, at what tem- 

 perature does it liquify?" This is a terrible question, for 

 if it is a gas, or matter at all, there must be a temperature 

 at which it will condense just as steam condenses to 

 water at 100 degrees Centigrade; and our instruments 

 should be able to determine this condensation through its 

 ray-emitting power. We want nothing better, though, than 

 this question. The emanation from thorium condenses 

 sharply at a temperature of 120 degrees below zero on the 

 Centigrade scale to a brilliant patch of phosphorescent light. 

 We proceed to inform our opponent that not only has the 

 emanation a definite liquifying point but that it obeys Boyle's 

 law in that, in a definite volume of air, its quantity is pro- 

 portionate to the pressure; and, further, that from its rate 

 of diffusion through air, or through a porous plug, its den- 

 sity has been determined by well-known methods as about 

 100 times that of hydrogen gas. We heap this up by say- 

 ing that we can even tell the particular family of the ele- 

 ments to which the emanation belongs; for since it is abso- 

 lutely indestructible and unchangeable under the most 

 drastic chemical treatment, it is, evidently, a gas belonging 

 10 



