60 Scientific Intelligence. 



pletely mix two liquids. Even if blocks of barium sulphate and 

 of sodium carbonate* were brought into actual chemical contact, 

 I think no one would expect that simple diffusion would complete 

 the interchange of bases and acids in finite time so long as both 

 substances remained solid ; nor that a piece of copper and of tin 

 soldered together would diffuse and form a homogeneous bronze ; 

 nor would they expect that simple cubic static pressure would 

 promote these reactions ; if pressure will assist them to comple- 

 tion, it will increase the diffusibility of solids, increase the 

 freedom of motion of their molecules, that is, it will make them 

 more like liquids, will begin to liquefy them. 



I wish to refer here to a new law I recently proposedf 

 concerning the formation of alloys, where the fact is brought 

 out that the melting point and liquidity of the product are quite 

 as important as those of the constituents in determining the 

 possibility of a reaction. Mr. Spring]; has produced Wood's alloy 

 by compressing the constituents together, and quotes Mr. Romna§ 

 as having failed to obtain fine platinum wire by electro-silver- 

 plating a platinum wire, drawing it down and dissolving off the 

 silver in nitric acid, because the silver and platinum alloyed under 

 the pressure of the , draw plate. Messrs. W, & L. E. Gurley, of 

 Troy, N. Y., have for several years made fine platinum wires by 

 the well known Wollaston|| method of casting silver around the 

 platinum and treating as above. In the note referred tof 

 I have described the production of Wood's alloy loithout pressure 

 at 100° C. of a tin-lead alloy at 190° C. of the sodium-potassium 

 alloy at ordinary temperatures, etc. Hence it appears to me that 

 pressure alone is the least important factor in the production of 

 the effects obtained in Mr. Spring's investigation. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Modern Theories of Chemistry ; by Dr. Lothak Meyer. 

 Translated from the German (5th edition) by P. Phillips Bedson, 

 D. Sc, etc., and W. Carlton Williams, B. Sc, etc. 8vo., pp. xliv, 

 588. London, 1888. (Longmans, Green & Co.) The present 

 English edition of Lothar Meyer's excellent book will be warmly 

 welcomed by American chemists, to many of whom it is already 

 well known in the original. No better evidence of the high ap- 

 preciation in which it is held abroad can be given than the fact 



*W. Spring, Bull. Soc. Chetn., xliv, p. 166, 1885. 



t W. Hallock, Science, Mar. 2, 1888, xi, p. 100, also Ostwald. Zeitschr. f. Phys. 

 Chem., vol. ii, 1888. 



± W. Spring, Ber. der deutsch. Chem. Gesell., xv, p. 595, 1882. § Ibid. 

 JGanot's Physics, Atkinson, New York, p. 76, 1883. 



