xxiv GENERAL SUMMARY OF SCIENTIFIC AND 



Professor Palmieri opportunity for making more interesting 

 observations on the electric condition of the volcanic smoke, 

 confirming the results of his previous labors as to the origin 

 of the electricity displayed in thunder-storms, etc. The En- 

 glish translation of Palmieri's work has afforded Mallet op- 

 portunity to prefix, by way of introduction, a masterly sum- 

 mary of the present state of seismology. 



The long-vexed question of the cause of the scintillation 

 of the stars lias received almost a complete elucidation at 

 the hands of Respighi its dependence upon the changes of 

 density in the upper strata of air seems to be completely es- 

 tablished by him. 



In Theoretical Chemistry the past year has witnessed very 

 few changes of importance. The science seems at last to 

 have reached a stage of comparative equilibrium. Kekule, 

 however, in a noteworthy paper, has given us his views upon 

 the meaning of the term " atomicity," or " equivalence," when 

 applied to atoms. He supposes a kind of intramolecular mo- 

 tion %mong these atoms, and divides atoms into monatomic, 

 diatomic, etc., according to the number of contacts made in 

 a given time. In w T ater, for example HOH the oxygen 

 atom strikes against both hydrogen atoms in the same time 

 that each hydrogen atom strikes one blow ; or, in other 

 words, oxygen makes two vibrations while hydrogen makes 

 one. He applies this conception to his theory of the benzol 

 nucleus of the aromatic series, and ingeniously explains away 

 some objections which had been raised against it. Another 

 thins; deservino; mention here is Professor Cannizzaro's Far- 

 aday lecture before the Chemical Society of London upon 

 " The Theoretic Teaching of Chemistry." Accepting fully the 

 theory of atoms and molecules, and believing that "this the- 

 ory affords the clearest, shortest, most exact, and most ac- 

 cessible summary of all that relates to the origin, meaning, 

 value, and use of empirical formulas and of equations," he 

 naturally concludes that " it ought to be introduced into the 

 teaching of chemistry at an early stage." " I do not hesitate 

 to assert," he says, " that the theory of atoms and molecules 

 ought to play, in the teaching of chemistry, a part analogous 

 to that of the theory of vibrations in the teaching of op- 

 tics." He affirms that " the solid base, the corner-stone of 

 the modern theory of molecules and atoms, is the theory of 



