Dr. Ka^e on the Compounds of Ammonia. 77 



Prop. VI. — That the ordinary/ ammonia salts ally themselves to the salts of the 

 copper and zinc class, which contain two equivalents oj" oxide. 



The subject of this proposition is one of the most remarkable which I have 

 been induced to adopt in the course of these researches, and the nature of the 

 evidence in its favour will require a cautious and detailed examination of the 

 Individual instances of replacement by which it is supported. 



I have pointed out already, briefly, that all those ammonia-copper, zinc, and 

 nickel combinations which are formed by solution in water, must be looked upon 

 as combinations of ordinary ammoniacal salts with metallic oxide and amidide of 

 hydrogen, as well as occasionally still more water, at least in their crystallized 

 condition. As the establishment of this principle becomes of great importance, 

 I shall again sum up the proofs of it, and notice one or two examples, which were 

 not at that time alluded to. The progress of the reaction, in which at first a 

 pure ammoniacal salt and a basic metallic compound is always formed, indicates 

 the nature of the resulting body very remarkably ; and when we consider that 

 the bodies generated by dry ammoniacal gas were in all cases quite different, the 

 evidence becomes almost complete ; likewise, where we find that in the quick- 

 silver compounds the formation of the ammonia-quicksilver body occurs from the 

 commencement, and we cannot trace any stage at which the deposition of a sub- 



cbloride and oxide of potassium, it appears quite natural that sal ammoniac should combine with 

 acids, as chloride of potassium does in some instances, and that there should be so, -f- (hcI-\- axd) 

 as there is so, -|- (ho -\- H\d) equivalent to acrOj -j- kg and 2cr03 4- kc^. On this view there is no 

 reason for the expulsion of chloride of hydrogen as being the weaker acid, but by heat the expulsion 

 of HC^ can easily be understood. We cannot, by heating so, -|- Ho.HArf, expel ho, without other 

 effects complicating the result ; but the reaction in the case of so, -|- Hc/.HAfZ takes place with greater 

 ease and completeness. The compound so, -f- Hcl, formed by Aim6, though not analyzed, evidently 

 resembles so, -{- ho ; and by the addition of ammonia a compound of an equivalent character should 

 be produced. Another similar case is the brown powder, so, + (cmo -f- Hci), which, when heated, 

 gives so, + CMC and h.c^, as there are so, 4- cmo.ho and so, + cuo.Hxd, which give precisely 

 similar results. Berzelius appears to have understood from my description, that when dry c^h is 

 passed over dry cmo.so,, the brown mass becomes moist from free sulphuric acid; that, however, is 

 not the fact, water is set free only when the sulphate of copper is not dry ; the brown mass does 

 not fume nor grow damp ; it does not give any indication of free acid. The body so, -|- cuo.cla is 

 perfectly definite and well characterized. 



