SILVER, POTASSIUM, ETC. 



SILVER, POTASSIUM, SODIUM, CHLORINE, 

 BROMINE, IODINE, AND SULPHUR. 



The atomic weights of these seven elements depend upon 

 each otlier to so great an extent that they can hardly be 

 considered independently. Indeed, chlorine, potassium, and 

 silver have always been mutually determined. From the 

 ratio between silver and chlorine, the ratio between silver 

 and potassium chloride, and the composition of potassium 

 chlorate, these three atomic weights were first accurately 

 fixed. Similar ratios, more recently worked out by Stas 

 and others, have rendered it desirable to include bromine, 

 iodine, sulphur, and sodium in the same general discussion. 



Several methods of determination will be left altosrether 

 out of account. For example, in 1842 Marignac* sought to 

 fix the atomic weight of chlorine b}^ estimating the quantity 

 of water formed when hydrochloric acid gas is passed over 

 heated oxide of copper. His results were wholly inaccu- 

 rate, and need no further mention here. A little later Lau- 

 rentf redetermined the same constant from the analysis of 

 a chlorinated derivative of naphthalene. This method did 

 not admit of extreme accuracy, and it presupposed a knowl- 

 edge of the atomic weight of carbon; hence it may be prop- 

 erly disregarded. Maumene's| analyses of the oxalate and 

 acetate of silver gave good results for the atomic weight of 

 that metal ; but they also depend for their value upon our 

 knowledge of carbon, and will, therefore, be discussed fur- 

 ther on with reference to that element. 



Let us now consider the ratios upon which we must rely 

 for ascertaining the atomic weights of the seven elements in 

 question. After we have properly arranged our data we 

 may then discuss their meaning. First in order we may 



*Compt. Rend., 14, 570. Also, Joum. f. Prakt. Chem., 26, 304. 

 f Compt. Rend., 14, 456. Journ. f. Prakt. Chem., 26, 307. 

 :!: Ann. d. Chim. et d. Phys., (3,) 18, 41. 1846. 



