W. Gibbs on the Atomic Weights of Elements. 247 
combining at a lower temperatute to NH,Cl. In this manner, 
among others Koppt and Hofmannt have shown that’ it is un- 
now we admit that the molecules of all substances occupy 
2 vols. in the gaseous state, and if the reasoning which has led 
chemists to double the old atomic weights of carbon, oxygen, sul- 
Phur, &c., be correct, it follows that the atomic weights of the 
teater number of the el ts must be doubled. For we find re 
_ 1. That nearly all volatile inorganic oxyds, chlorids, oxyehlo- 
Mids &e. contain’ in 2 vols. of vapor ae 1) two or four received 
gluvalents of metal or radical. Thus the compounds ed 
formulas are now usually written SiCl,, TiCl,, ZCl,, SnCl., 
and niac heitee cna 
Vapor even at a temperature of 1040° C, At this temperature ammonia must © re 
Tesolved into its jose and its vapor-density ought to correspond, ply pated 
Ccxtof 4. The explanation in the text is therefore not applicable : 
