298 Proceedings of the Royal Irish Academy. 



Eliminating r'" between (A) and (C), we find 



3^3^ + ^ 

 <0 = — 



m 

 We thus find 



/" = 1, .;m3 = - ^, /5 = 14, 



^3(3^3+^3)" 





11 



»«3 



~ ""6"' 



a)'"2 . 



= 2-3884, 



/"^ = 



= + 0-0794. 



As ammonia (NH3) is formed, to the exclusion of (NHj) and 

 (NH), we must examine these two compounds. 

 The most probable constants for NHj, are^ 



r" =1, m, = ^ = - 3, i8 = 14, 



a)"2 = ^ = 1'7778, 



^"y8 = + 0-7778. 

 The most probable constants for NH are 



mi = - 6, ^ = 14, 



a)'2 = 1-0850, w'V = M859, 



r' - 1-0930, //? = + 1-6263. 



Phosphuretted Hydrogen. — The fact that phosphorus has a tetra- 

 tomic molecule, and not a diatomic molecule, as nitrogen, does not 

 alter the fundamental equations already given (A) (B) and (C), for 

 we must introduce a sufficient number of hydrogen molecules to make 

 up the result, and the fundamental equations remain unchanged.^ 



1 NH2 is not known in the separate form ; but N2H4 <^ has recently been 



obtained by Curtius. 



^ The same would apply to sulphur considered as diatomic, tetratomic, or 

 hexatomic ; also to arsenic and antimony, and farther on to carbon and silicon, 

 which may be treated as diatomic or tetratomic at pleasure. 



