68 Notices respecting New Booh. 



France. British chemists have hardly entered on the investiga- 

 tions," 



In the compilation of this w^ork, Dr. Thomson has exerted much 

 patient industry; for as the analyses were chiefly made in foreign 

 countries, it required for its completion numerous references, not 

 merely to French works which are in the hands of many English 

 chemists, but to German works, which are much less readily ob- 

 tained, and less perfectly understood. 



Some idea of the extent of the information contained in this work 

 maybe formed from merely stating the fact, that it consists of more 

 than 1000 closely-printed octavo pages. It consists of four divi- 

 sions : 1st. ^'egetable principles, comprehending the vegetable acids 

 and vegetable alkalis, intermediate bodies, oils, resins, &c. &c. ; 

 the 2nd division includes the parts of plants ; the 3rd treats of vege- 

 tation ; and the last, of the decomposition of plants. 



Dr. Thomson, by thus collecting the numerous facts relating to 

 vegetable bodies into one volume, has performed a most useful and la- 

 borious task. We are not aware of the existence of any similar 

 work, even on the continent ; and the English chemist had to search, 

 and not always with success, through a mass of foreign journals, for 

 the knowledge which he will now readily acquire ; and we strongly 

 recommend it to such as wish to acquire information on the im- 

 portant branch of chemistry to which it is dedicated. The mode in 

 which the work has been conducted will be readily appreciated by 

 the selection which we have made of the chapter on Pyroxylic 

 Spirit for a separate article, a part of which appears in our present 

 number. 



Memoire sur VIrradiation par J. Plateau, Memhre de V Academic 

 Roy ale des Sciences de Briixelles, Professeur a VUniversite de 

 Gand, 8iC. — Bruxelles, 1839. 



[Extrait du tome xi. des Mdmoires de VAcad. Roy. des Scienc. de JBruxelles.] 

 A copy of the above memoir has just reached us, the Report upon 

 which to the Royal Academy of Brussels at its sitting Aug. 5, 1837, 

 we here insert. 



Optics. — M. Plateau has presented to the Academy a memoir on 

 irradiation. " The object which I have proposed to myself in this 

 memoir," says the author, "is to put an end to the uncertainties 

 which still exist amongst astronomers and physicists as to the very 

 existence of irradiation, and to examine the causes of the phoeno- 

 menon, its influence in astronomical observations, and the laws to 

 which it is subject, rather more closely than has hitherto been done. 

 " Irradiation is the phaenomenon by virtue of which a luminous 

 object surrounded by an obscure space appears more or less ampli- 

 fied. It is usual to cite as an example the appearance which the 

 moon exhibits when she is seen in the form of a crescent, and at 

 the same time allows the remainder of her disk to be distinguished, 

 feebly illuminated by the ash-coluured light. The exterior contour 

 of the luminous part then seems to present a marked projecture on 

 that of the obscure part; in other words, the crescent appears to 



