362 Professor Connell on the 



water precipitates lime salts, and effervesces with, acids. But 

 if ammonia, per se, is an alkaline base, are we, on that account, 

 to reject the idea of the existence of ammonium and its oxide / 

 I think that we are not bound to do so ; but we shall be bet- 

 ter enabled to admit the existence both of the alkali ammonia 

 and the alkali oxide of ammonium, if we call in the aid of 

 some of those analogies to which I have been alluding. The 

 compound of a hydracid with an oxyalkali has a constant ten- 

 dency to pass into the state of a haloid salt, by losing the 

 elements of water. The compound of an oxyacid with a 

 hydralkali, in the anhydrous state, exists rarely, and the con- 

 stituents are not usually in their proper condition of acid and 

 base, as we see in anhydrous sulphate of ammonia. The na- 

 tural tendency of ammonia, as a hydralkali, thus is, not to 

 combine with oxyacids, but rather with hydracids; and we 

 have instances of such unions in muriate, hydrobromate, and 

 hydriodate of ammonia, &c. 



On the other hand, the natural tendency of oxyacids is to 

 unite with, oxybases, at least with a view to the formation of 

 permanent and distinct compounds ; and thus we are led to 

 certain peculiarities in their apparent unions with hydrobases. 

 When w^e find ammonia apparently entering into union with 

 oxyacids, we usually discover the elements of an atom of water 

 also existing in the compound. To what are we to attribute 

 this fact \ I apprehend the solution is to be found in a dispo- 

 sition of nature to pass into a new analogy, or new series of 

 combinations, moulded on a different type from the proper 

 ammoniacal saline compounds. To enable a hydralkali to form 

 a compound with an oxyacid, it must in some way fulfil the 

 condition of passing into the state of an oxyalkali ; but, as the 

 hvdrogen compounds constitute the proper and principal series 

 of hydrobase unions, we need not look for the same perfection 

 of purpose in carrying out the new analogy. Ammonia, by 

 uniting with the elements of an atom of water, passes into the 

 condition of oxide of ammonium, a base belonging to a differ- 

 ent series, and of a less perfect nature. It is less perfect 

 than ammonia, because it cannot exist in an uncombined state, 

 and because its salts are decomposed by heat, whilst the hy- 

 dracid salts of ammonia sublime unchanged ; and, for similar 



