M. Dumas on the Equivalents. 209 



opposite poles, which cut each other, cut off equal and similar 

 portions from each other. In the critical case, the meridional 

 arc, which corresponds to the intercepted tangent in the stereo- 

 graphic projection, is therefore also constant. 



The following Table contains all the elements necessary for 

 tracing the meridional curve. The third column contains the 

 meridional parts corresponding to the latitude ; and the fourth 

 the actual value of log, cos (p. 



6 Brompton Grove, 

 August 12, 1858. 



XXIII. Chemical Notices from Foreign Journals. 

 By E. Atkinson, Ph.D. 



[Continued from p. 140.] 



CONSIDERABLE attention has of late been given to the 

 question of the atomic weights of the elements ; and seve- 

 ral important papers have been published upon this subject by 

 Dumas, Pettenkofer, Marignac, and v. Hauer. 



Dumas* makes known, in a preliminary communication, the re- 

 sults of a general revision of the equivalent weights of the elements 

 which he has undertaken, and on which he is still engaged. 

 He also points out and discusses various important and in- 

 teresting relations which exist between the elements. In this 

 respect his views are a development of those expressed at the 

 meeting of the British Association in 1851. 



The majority of recent determinations of the elements have 

 led to the confirmation of Prout's law that the equivalents of all 

 elements are exact multiples of that of hydrogen. Two of the 

 most important formed exceptions, chlorine and copper; and 

 although the equivalent of chlorine has been ascertained with 



* Comples Rendus, vol. xlv. p. 7^9. Lie])ig's Annalcn, January 1858. 

 Phil. May. S. 4. Vol. 16. No. lOG. Sept. 1858. P 



