392 Scientific Intelligence. 



suppress the anterior teeth of the second series or intercalate 

 them with teeth of the first series ; the molars became trituber- 

 cular. 2, The higher Placentals retained the succession of 

 the first and second series as far back as the first molar ; the 

 molars entered rapidly into trituberculy and its higher stages. 

 B, forms retaining the double succession in part of the molar 

 region, and retaining more of the primitive dentition, 4, 1, 4, 

 8. 3. The Edentates branched off from an early triconodont 

 or tritubercular diphyodont stage, with numerous molars, and 

 secondarily suppressed the first heterodont series, and estab- 

 lished a numerous homodont second series. 4. The Cetacea 

 also branched off from a diphyodont, heterodont stage, and 

 secondarily established a numerous homodont first series, and 

 suppressed the second series. 



[To be continued.] 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On the Effect of Temperature on the Rotatory Power of 

 Liquids. — It has been shown by Aignan that in cases where a 

 liquid is optically inactive because it is a mixture of two active 

 substances of opposite rotatory powers, the inactivity, as a rule, 

 will hold only for rays of a certain wave-length. In consequence 

 the mixture will be active in one direction for rays of shorter 

 wave-length and active in the opposite direction for rays of 

 greater wave-length. This phenomenon is well shown, for ex- 

 ample, with mixtures of lsevogyrate terebenthene and dextrogyrate 

 camphene. Moreover, in such liquids the optical equilibrium will 

 be disturbed by a change of temperature; the liquid becoming 

 active in one direction when the temperature rises and in the 

 other direction when the temperature falls. This phenomenon, 

 also, is observed with mixtures of terebenthene and camphene. 

 With red rays the rotatory power changes sign between 61° and 

 73°, and with yellow rays between 13° and 33°; while with green 

 rays the liquid is always dextrogyrate between 13° and 90°, the 

 rotatory power increasing with the temperature. Phenomena of 

 this kind were long ago observed by Biot in the case of solutions 

 of tartaric acid. And the author suggests that the results obtained 

 by Colson ( C. H., cxvi, 319) are explicable on the supposition that 

 the liquids used by him are mixtures of two substances of oppo- 

 site optical activities, the variations in the rotatory power being 

 due to the causes above mentioned. — C. JR., cxvi, 725; J. Chem. 

 Soc, lxiv, II, 354, August, 1893. G. f. b. 



2. On the Flame /Spectra of Metals.— The ultra-violet portion 

 of the flame spectra of the salts of certain metals has been photo- 



