THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



MARCH 1842. 



XXVII. Abstract qfT)v. Hermann Kopp's Researches on the 

 Specific JPeight of Chemical Coinpmmds*. By Henry 

 Croft, Esq., Teacher of Chemistry f. 



/CHEMISTS have lately commenced directing considerable 

 ^-^ attention to the "atomic volumes " of bodies, that is to 

 say, the space occupied by an atom of any body, or, in other 

 words, the quotient of the density into the atomic weight. In 

 one of the preceding volumes of this Journal, Dr. Kopp has 

 shown that perfectly isomorphous bodies possess the savie 

 atomic volume, and that in the cases of those bodies which 

 are not perfectly isomorphous, every difference in the crystal- 

 line form is expressed by a difference in the atomic volume. 

 The same author has lately published a work, entitled "Uber 

 das specifische Gewicht der Chemischen Verbindungen," in 

 which he discusses the composition of chemical bodies ac- 

 cording to the volumes of their elements. The following is a 

 short abstract of this work, which it seems very desirable to 

 make known to English chemists. Dr. Kopp has struck out 

 an entirely new branch in molecular chemistry, which pro- 

 mises to be hereafter of very great importance. The first at- 

 tempt to determine the composition of bodies according to 

 the volumes of their elements was made by Schroder (Pog- 

 gendorff's Annals, 50, p. 553), but many objections may be 

 raised to the manner in which this attempt was made, and to 

 the conclusions therein deduced ; a critique, by Dr. Kopp, of 

 this work appeared in the 52nd volume of the same Journal. 

 In his researches on the same subject, Dr. Kopp has en- 



* Uber das Specifische Gewicht der Chemischen Verbindungen. Frank- 

 furt. 1841. 



f Ci)ininiinicatcd by the Author. Dr. Kopp's paper on tiie atomic vo- 

 lume and crystalline condition of bodies will be found in Phil. Mag. Third 

 Scries, vol. xviii. p. 2.5.1. 



Phil. Mail. S. 3. Vol. 20. No. 1 30. March 1842. N 



