417 



cyanide, sulphuret, and chloride of hydrogen ; from all of which 

 bodies it is possible, as from ammonia, to expel an atom of hydro- 

 gen, and to replace it by an atom of metal, — if indeed hydrogen be 

 not (as there seems to be a tendency to believe it to be) itself of 

 metallic nature, notwithstanding its highly rarefied form. By de- 

 veloping this view of the constitution and function of ammonia. Dr. 

 Kane has offered explanations of a large number of replacements of 

 that substance by others, some of which replacements (I believe) 

 were known before, while many have been discovered by himself. 



One of the most remarkable points in Dr. Kane's views is the 

 way in which he considers the ordinary salts of ammonia. Many 

 of these are known to contain an atom of water, the existence of 

 which led to the proposition of the very remarkable theory by Ber- 

 zelius, of the existence in them of a compound metal ammonium^ 

 which has not indeed been insulated, but has been found to form, 

 in combination with mercury, a certain metallic amalgam. Dr. 

 Kane looks upon these salts as double salts of hydrogen. He con- 

 siders them to contain ammonia ready formed, united with a hydrated 

 acid or with a hydrogen acid. He seeks to establish the similarity 

 of the common ammoniacal salts to those complex metallic anii- 

 dides, whose nature he has developed by analysis. 



Thus, for example, the well-known body, sal-ammoniac, is, in 

 the Berzelian view, regarded as chloride of ammonium ; but, in 

 the view put forward by Dr. Kane, it is chlor-amidide of hydrogen. 

 The former view supposes that the ammonia robs the hydrochloric 

 acid of its hydrogen, to form, by a combination with it, a metallic 

 base,NH^, with which the chlorine unites; as this last element com- 

 bines with the metal sodium, in the formation of common salt. The 

 latter view supposes that in the action between hydrochloric acid and 

 dry ammoniacal gas, there is no separation of the chlorine from the 

 hydrogen,— no breaking up of a previously existing union, — no 

 overcoming of the affinity which these two elements (chlorine and 

 hydrogen) have for each other; but an exemplification of a general 

 tendency of chlorides, oxides, and amidides of the same or similar 

 radicals, to unite, and form chlor-oxides, chlor-amidides, or oxami- 

 dides. Sal-ammoniac is, according to Kane, a double haloid salt ; 

 he looks upon it as being a compound exactly analogous to the 

 white mercurial precipitate, which was first accurately analyzed by 



