MODERN TENDENCY OF PHYSICAL SCIENCE. t2Q 



in the golden age of Chemistry, near the early part of last century, 

 and to discard everything relating to an ether of space. 



il The ionisation doctrine and its many developments may 

 be regarded as an encroachment of physics on the preserves of 

 chemistry, since it has certainly modified ideas about the nature 

 of solution ; but there is a converse process now going on, and 

 in the course of a sort of triumphant materialisation of obscure 

 entities, achieved at any rate hypothetically and speculatively, if 

 m it yet in any substantial manner. Chemistry seems to be domi- 

 nating emancipated parts of Physics. 



" The latest and most astonishing attempt towards the re- 

 conversion of Physics into Chemistry appears in a brilliantly 

 clever and apparently serious address to Section A by Professor 

 Callendar, this year, on the resuscitation of caloric or the material 

 theory of heat — a theory which carries with it the ancient view 

 that physical changes of state, such as vaporisation and liquefac- 

 tion, are really the solution of matter in the substance of that 

 apparently imponderable material caloric, and vice versa. 



" After this it is barely surprising to hear the biologists call 

 upon the chemists to explain the phenomenon of life, and to 

 produce in their glass vessels — if only they can stumble on the 

 right environment, and on a judiciously combined assortment of 

 material — some low form of living matter. 



" In view of the remarkable experiments recently made on 

 the influence of various strengths of mere salt solutions in fer- 

 tilisation and cross-breeding, it is not surprising that an anticipa- 

 tion of the kind should be promulgated. At present it is no 

 more than a speculation, but if followed up, although it may not 

 lead to the result anticipated, it may lead to others of perhaps 

 equal interest. 



" All this tendency to return to discarded hypotheses and 

 revivify old beliefs — for spontaneous generation is. I suppose, a 

 very old belief or superstition— is a matter of great interest; and 

 it is astonishing to find how much can stilly be said for ancient 

 views. Forty years ago the Caloric theory of heat seemed dead 

 beyond redemption, and I do not say it yet lives, but the ingenuity 

 of Professor Callendar finds a great deal to say for it, some of 

 it of a cogent kind ; it appears to be quite a possible mode of 

 expressing facts, and one that is perhaps convenient for several 

 non-elementarv ] >ur] >< >ses. 



" Then, again, in early days it was customary to jeer at the 

 prevalent popular habit of speaking of electricity as a fluid, and 

 until we knew more about it the practice was certainly to be 

 deprecated ; but now, in the light of further knowledge, something 

 very like an improved and more definite fluid theory seems likely 

 to hold the field. 



