282 Dr. Hofmann on the Chemical Type: Ammonia. [May 16, 



which gives rise to the formation of iodide of silver, separating as 

 a precipitate and of the hydrated ammonium -oxide, corresponding 

 to the above-mentioned iodide or hydrated oxide of tetrethylam- 

 monium,* which remains in solution. The following equation 

 elucidates this change — 



N 



I + AgO + H0 = Agl + N 



0,H0 



Iodide of tetre- Hydrated oxide of 



thylammonium. tetrethylammonium. 



The solution of this compound oxide of ammonium may be 

 evaporated to dryness without decomposition ; a crystalline sub- 

 stance is thus obtained of a most powerfully alkaline character, 

 resembling in every respect hydrated potassa itself. A concentrated 

 solution of this substance not only burns the tongue, but acts upon 

 the epidermis which it destroys like potassa or soda. On rubbing 

 the solution between the fingers, the well-known soapy sensation 

 produced by the fixed alkalies under the same circumstances is felt. 

 Moreover the same peculiar odour is perceived. Oxide of tetre- 

 thylammonium saponifies the fats without difficulty ; beautiful soft 

 soaps are thus obtained, possessing all the properties of ordinary 

 potassa-soap. All the chemical effects produced by potassa or 

 soda, are likewise produced by oxide of tetrethylammonium ; and in 

 its deportment with the salts of the metals especially, the compound 

 oxide of ammonium can scarcely be distinguished from the fix^d 

 caustic alkalies. 



The formation of oxide of tetrethylammonium is certainly one 

 of the most powerful props which the ammonium-theory could have 

 received, and since this support has been entirely and exclusively 

 furnished by researches performed within the domain of Organic 

 Chemistry, it must be admitted that the researches made in this de- 

 partment of the science, and especially the elaboration of the com- 

 pound derivatives of the type ammonia, begin to react most power- 

 fully and beneficially upon the progress of Mineral Chemistry.^ 



[A. W. H.] 



* In three beakers, boiling solutions of iodide of tetrethylammonium (1), 

 of iodide of ammonium (2), and of iodide of potassium (3), were mixed with 

 freshly precipitated oxide of silver. The beakers were then covered with 

 reddened litmus paper and glass plates ; after a few moments the paper covering 

 solution (2), was found to have become intensely blue, in consequence of the 

 volatilized ammonia-gas ; whilst the papers covering solutions (1) and (2) did not 

 exhibit the slightest alteration, the liberated oxides of tetrethylammonium and 

 of potassium not being volatile. On dipping, however, reddened litmus paper 

 into these two solutions, they were found to be powerfully alkaline. 



t At the conclusion of the discourse, the ammonium-amalgam was prepared 

 on a large scale by the action of potassium-amalgam upon a solution of chloride 

 of ammonium. 



