Dr. Kane on the Compounds 0/ Ammonia. 65 



as leading to any thing like the general principle which formed the subject of my 

 paper. Since that period, although no writer has broadly reproduced this theory 

 of the hydrogen combinations, yet the progress of research has gradually lent to 

 it the most efficient support, by the discovery of classes of bodies identifying in 

 the strictest manner the chemical relations of hydrogen, and of certain of the 

 more positive among the metals. The beautiful investigations of Graham on 

 water as a constituent of salts, particularly those illustrating the conversion of the 

 neutral into the basic condition by the replacement of the hydrogen by a metal 

 of the magnesian family, has shown that in its relations to oxygen at least no line 

 of distinction can be drawn between hydrogen and the metals which with it 

 constitutes so natural a group. 



Passing to the other compounds of hydrogen, there will be found in the 

 series of researches on the zinc and copper families, a variety of instances in 

 which the chloride of hydrogen is represented with remarkable closeness by the 

 chlorides of copper or of zinc. The examination of the various oxychlorides of 

 zine, in their dry and hydrated conditions, which presents to us the perfect 

 analogues of the chloride of hydrogen in its two stable conditions of definite 

 combination with water, points out an identity of action liable to little objection. 

 Like the chloride of hydrogen also, chloride of zinc is caustic, and when con- 

 centrated reddens litmus, so that the peculiarly acid character of affecting that re- 

 agent is to be found well developed in bodies to which, under any circumstances 

 of ordinary language, the name of acid could scarcely be applied. 



The relation of chloride of zinc to ammoniacal gas is likewise very remarkable, 

 as indicating the general similarity of action between the hydrogen and zinc 

 compounds : the volatility of the ammonia-chloride of zinc, the permanent nature 

 of the ammonia-chloride of copper, indicate a closeness of union between the 

 metallic chloride and the ammoniacal gas, which brings those bodies into very 

 intimate connexion indeed with sal ammoniac. 



As this proposition will receive from the evidence of several of the succeed- 

 ing ones a great deal of additional support, 1 will not here enter into any further 

 evidence in favour of it. Every fact which, in the course of these researches, be- 

 came the subject of examination, has tended to strengthen my confidence in the 

 truth of the general principle which the additions to science from the recent 

 investigations of other chemists have likewise uniformly tended to confirm. 



VOL. XIX. K 



