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THE POPULAR SCIENCE MONTHLY 



POPULAR MISCELLANY. 



British Association Addresses. — Profess- 

 or Eoscoe's address before the Chemical 

 Section was on " The Progress of Chemis- 

 try since 1848." The author made the year 

 1848 a dividing line between the epoch of 

 Berzelius, which closed then, and that of 

 Dumas and Wurz, which closed in 1884. 

 The differences between the two epochs are 

 shown in the distinct views which were en- 

 tertained as to the nature of a chemical 

 compound. According to the older notions, 

 the properties of compounds were deter- 

 mined largely by the qualitative nature of 

 their constituent atoms, and these were ar- 

 ranged so as to form a binary system. Ac- 

 cording to the newer view, it is* mainly the 

 number and arrangement of the atoms in 

 a molecule that regulate the characteristics 

 of a compound, which is to be regarded, 

 not as built up of two constituent groups 

 of atoms, but as forming a single group. 

 The theory of substitutions, the relation of 

 atomic weights and volume-combination, the 

 prominent part assigned to organic radicals, 

 the doctrine of valency or atomicity, and 

 Mendelejeff and Lothar Meyer's periodic 

 law, under which we may predict the nature 

 and place of as yet undiscovered elements, 

 and the study of isomeric phenomena, are 

 also distinctive marks of the later chemis- 

 try. The artificial synthesis of a few col- 

 oring-matters and of kairine, a febrifuge 

 as powerful as quinine, are among its most 

 noteworthy achievements. Of the work 

 that has been done in the determination of 

 chemical constants, the labors of Mallet on 

 aluminum, of J. P. Cooke on antimony, and 

 of Thorpe on titanium, are especially men- 

 tioned. The speaker gave accounts of the 

 progress that has been made in spectrum 

 analysis, and the close distinctions of the 

 molecular properties and constitution of 

 bodies which it has made possible. Other 

 indications of progress are given in Sir Will- 

 iam Thomson's speculations on the probable 

 size of the atoms ; Helmholtz's discussion 

 of the relation of electricity and chemical 

 energy ; and the theory of the vortex-ring 

 constitution of matter, as suggested by Sir 

 William Thomson and worked out by Mr. 

 J. J. Thomson. Much experimental atten- 

 tion is now given to thermo-chemistry. The 



discovery of the liquefaction of the gases 

 by Pictet and Cailletet, including Andrews's 

 discovery of the critical point, indicates a 

 connection, long unseen, between the liquid 

 and the gaseous states. Deville's investiga- 

 tions of the laws of dissociation have opened 

 out entirely fresh fields for research, and 

 given new, important, and interesting views 

 concerning the stability of chemical com- 

 pounds. Professor Roscoe considered the 

 best methed of educating chemists to con- 

 sist in giving them as sound and extensive a 

 foundation in the theory and practice of the 

 science as their abilities will allow, rather 

 than in forcing them prematurely into origi- 

 nal preparations and investigations. 



Mr. W. T. Blanford, President of the 

 Geological Section, presented some remarks 

 upon contradictions which had been ob- 

 served in certain districts, in the determina- 

 tion of the age of geological formations as 

 indicated by their fossils. The most of them 

 occur where a land or fresh-water fauna or 

 fiora assigned to a particular formation rests 

 upon a marine bed of apparently later ori- 

 gin : as in Greece, where the supposed Mio- 

 cene fauna of the Piker mi beds overlie 

 strata with Pliocene mollusca ; and in cer- 

 tain described places in India, Australia, 

 and South Africa. Only one case of con- 

 tradiction between two marine formations 

 is known, and that is in dispute. In making 

 choice between the two witnesses, geolo- 

 gists take the marine formations ; for ma- 

 rine faunas and floras are more widely dif- . 

 fused than those of the land, and more near- 

 ly uniform throughout the world. Thus, of 

 fishes, eighty families are typically marine, 

 and twenty-nine are confined to fresh water ; 

 of the fiirst, fifty are universally or almost 

 universally distributed ; while of the second, 

 only one is found in five of Wallace's re- 

 gions, and not one is met with in all the six 

 regions. Among plants, so uniform is the 

 marine vegetation of the world, that no 

 separate regions can be established in the 

 ocean, while Drude makes fourteen on the 

 land. It appears to the author that at the 

 present day the difference between the land 

 faunas of different parts of the world is so 

 vastly greater than that between the marine 

 faunas that, if both were found fossilized, 

 while there would be but little difficulty in 



