LITERARY NOTICES. 



419 



ed it as an expression of a basal truth in 

 nature. The history of -the growth of this 

 conception consequently forms one of the 

 most interesting chapters in the develop- 

 ment of scientific ideas ; while an exposition 

 of its principles affords the completest ex- 

 emplification of the views now entertained 

 of the structural and constitutive laws of 

 matter. 



All books upon chemistry are now to a 

 certain extent treatises upon the atomic 

 theory, which becomes more and more in- 

 dispensable as this science increases in ex- 

 tent and complication. The latest phase 

 of chemical progress the "New Chemis- 

 try," as it is called is entirely pervaded by 

 atomic and molecular theories, while mo- 

 lecular physics is now more completely co- 

 ordinated with chemistry through the inter- 

 vention of the atomic hypothesis than has 

 ever been possible before. So important 

 has this idea become, that special treatises 

 are required to deal with it. The " New 

 Chemistry" of Professor Cooke is one of 

 the ablest of these expositions, and has 

 done a most valuable service to education 

 by facilitating the mental transition from an 

 old to a new order of ideas. 



Yet the subject is one of so many as- 

 pects and such deep and comprehensive 

 significance that it can not be exhausted in 

 any single treatise. There was need for a 

 book like this of Professor Wurtz, which 

 discusses the atomic theory both in its 

 historic evolution and in its present form, 

 with the view of bringing out clearly the in- 

 fluence it has exercised upon the progress 

 of science since the beginning of the century. 

 And perhaps no other man of this age could 

 have been selected so able to perform the 

 task in a masterly way as the illustrious 

 French chemist who contributed the present 

 volume to the " International Scientific Se- 

 ries." He gave himself early to chemistry, 

 and became chief of the chemical department 

 in the Medical Faculty at Strasburg, at the 

 age of twenty-two. He was soon after called 

 to Paris, and became at once connected with 

 its great scientific institutions. After the 

 death of the celebrated toxicologist Orfila, 

 in 1853, and the retirement of Dumas in 

 1854, their chairs were united in that of 

 Medical Chemistry and given to Wurtz. In 

 1867 he became a member of the French 



Academy of Sciences, which had previously 

 awarded him a prize of twenty thousand 

 francs. He has written much upon chem- 

 istry, pure and applied, and has paid great 

 attention to the history of chemical doctrines. 

 Among Enghsh translations of his works 

 are, " Chemical Philosophy, according to 

 Modem Theories" (1867), and "Theory 

 from the Age of Lavoisier " (1869). "The 

 Atomic Theory " is his last and crowning 

 work, and it has a special authority derived 

 from its author's critical study of chemical 

 progress in the present century. 



It is impossible to convey to the reader, 

 in a notice like this, any adequate idea of 

 the scope, lucid instructiveness, and scien- 

 tific interest of Professor Wurtz's book. 

 The modern problems of chemistry, which 

 are commonly so obscure from imperfect 

 exposition, are here made wonderfully clear 

 and attractive. The statements are suffi- 

 ciently full without being overdone, the 

 writer's object being simply to make the 

 reader understand the topic that is treated. 

 Many passages might be quoted ; here is 

 the account of the " vortex theory," taken 

 from the final chapter of hypothesis upon 

 " The Constitution of Matter " : 



In these later times a theory has arisen which 

 seems to grive a mathematical demonstration, 

 and even an experimental illustration, of the in- 

 divisibility, or rather of the peculiar and eternal 

 individuality, of atoms: I refer to the vortex 

 atoms of Sir William Thomson. 



Chemists can form an idea of this vortex 

 motion by recalling to mind the rings which rise 

 in still air whenever a bubble of phosphoretted 

 hydrogen bursts upon the surface of water, and 

 the rings which certain smokers are able to 

 make are familiar to all. An apparatus has been 

 constructed by which they may be produced at 

 wiU. It is a wooden box, one side of which is 

 furnished with a circular opening, and the other 

 formed of a tightly stretched cloth. In the in- 

 terior of the box fumes of sal-ammoniac are 

 produced, which are driven out by a sharp blow 

 on the elastic side. A ring of smoke is then seen 

 to issue from the opening, and to move freely 

 through the room. In this ring all is motion, 

 and, independently of the motion of translation, 

 the smoke-particles roll over each other and 

 execute a rotary motion in every section of the 

 ring. These motions take place from the in- 

 terior toward the exterior of the ring, in the 

 direction of the motion of translation, so that 

 the entire mass of air, or of the smoke which 

 forms the ring, revolves continually round a cir- 

 cular axis, which forms, as it were, the nucleus 

 of the ring. There is this remarkable fact in 

 this rotary motion, that all the particles which 



