318 Miscellaneous Intelligence. 



temperature of stars presumably many times more fervent than 

 our sun, as Sirius and Vega. 



"Taking all these matters into consideration, we need not he sur- 

 prised if the earth-bound chemist should, in the absence of celes- 

 tial evidence which is incontestable, continue, for the present at 

 least, and until fresh evidence is forthcoming, to regard the ele- 

 ments as the unalterable foundation-stones upon which his science 

 is based." 



Another new contribution to the question of the decomposa- 

 bility of the elements is that made by Crookes, who, by means of 

 the spectra of the phosphorescent light of some rare earths under 

 an electric discharge in a vacuum, ascertained the possible presence 

 of new elements, showing, as in the case of yttria, either that the 

 bodies yielding the different phosphorescent spectra are different 

 elementary constituents of the substance which we call yttria ; 

 or, in consideration of their yielding the same spark-spectrum, 

 " adopting the very reasonable view that the Daltonian atom is 

 probably, as we have seen, a system of chemical complexity, and 

 to this adding the idea that these complex atoms are not all of 

 exactly the same constitution and weight, the differences, however, 

 being so slight that their detection has eluded our most delicate 

 tests with the exception of this one of phosphorescence in a 

 vacuum." A third possible explanation is suggested by Marig- 

 nac — the presence of traces of foreign bodies, introduced in the 

 course of the thousands of separations which have to be made before 

 the differences become manifested. Dalton showed that gases dif- 

 fuse into one another; and Graham later, but over fifty years 

 since, that the relative rates of diffusion are inversely proportional 

 to the square roots of their densities. But Joule, in his papers on 

 the mechanical equivalent of heat, and on the constitution of elec- 

 tric fluids, expressed the movements in figures, and established " the 

 foundation of chemical dynamics and the basis of thermal chem- 

 istry ; and he added the further fact that " when electrical energy 

 is developed by chemical change a corresponding quantity of 

 chemical energy disappears." Another step onward, in the direc- 

 tion of electrical chemistry has been taken in establishing the fact 

 that an intimate relation exists between chemical activity and elec- 

 trical' conductivity. 



Dalton was the first to point out the existence of distinct com- 

 pounds consisting of the same constituents in the same percent- 

 age quantity. On this as a starting point, the science of organic 

 chemistry has been built up through the addition of the principle 

 as to the combining capabilities of elements, or their valency, the 

 nature and relations of radicals, and the principle of substitutions. 

 Further results have come from consequent advances in organic 

 synthesis. Sir Henry Roscoe treats briefly also of the progress 

 made in the theory of animal heat and other questions connected 

 with pathological chemistry. 



This brief abstract of the presidential address is made from the 

 full report of it in Nature of September 1. Nature of September 8, 



