1856.] 



the Chemical Type: Ammonia. 



281 



By assuming the existence of this hypothetical metal in the salts 

 of ammonia, the nature of these substances, their analogy with the 

 salts of the fixed alkalies, and especially the isomorphism of the 

 salts of ammonia and potassa, became at once intelligible. The 

 following table exliibits the ammoniacal salts (represented firstly, 

 as combinations of ammonia, with hydrated acids ; and secondly, 

 as «mwowrwm-compounds ;) in juxtaposition with the corresponding 

 terms of the potassium-series. 



The analogy of chloride, sulphate, and nitrate of ammonium, 

 with the corresponding potassium-compounds, is complete, but the 

 analogy begins to fail when we compare the oxides of ammonium and 

 potassium. Oxide of potassium, potash, is a perfectly definite body, 

 the properties of which, especially in its hydrated condition, are 

 well known. On the other hand all attempts to isolate the oxide of 

 ammonium or its hydrate have been hitherto abortive. Liberated 

 from one of the ammonium-compounds it splits at once into ammonia- 

 gas and water, even at the common temperature. The impossibility 

 of producing the oxide of ammonium has been always adduced as an 

 argument against the ammonium-theory. 



This difficulty disappears entirely if we examine the deportment 

 of some of the compounds briefly described in the preceding part 

 of this discourse. By again submitting triethylamine, that is am- 

 monia containing three equivalents of ethyl in the place of three 

 of hydrogen, to the action of iodide of ethyl, a beautiful crystalline 

 compound is obtained, the composition of which is represented by 

 the formula — 



N 



that is iodide of ammonium, in which the four hydrogen-equivalents 

 are replaced by a corresponding number of equivalents of ethyl, or 

 iodide of tetr«thijlamnwnium. If this compound be treated with 

 freshly precipitated oxide of silver, a decomposition takes place, 



