Chemical Powers of Ammoniacal Salts. 257 



solution repeatedly through a filter holding the oxide. Such ex- 

 amples are however, of far less importance than those which il- 

 lustrate the action of the fused salts. 



Nitrate of ammonia melts at a temperature a little above 280°F. and 

 exposed to this degree of heat, duly regulated, gradually evaporates but 

 preserves its fluidity to the last. In this particular condition it readily 

 dissolves solids, like other fluids, and always possesses very strong 

 acid and oxidating properties. Carbonates disappear, with brisk ef- 

 fervescence, and several metals are oxidated with prodigious violence j 

 when muriates, as of ammonia or soda, are mixed, they become 

 dissolved, a brisk effervescence ensues and concentrated nitro muri- 

 atic acid is gradually formed. The muriate of ammonia is pref- 

 erable to that of soda, or any other with a fixed base, because the 

 excess may be removed by sublimation. The mixture of these salts 

 which may be styled a nitro-muriate, when fused, dissolves gold 

 leaf with the greatest ease and when assisted by the addition of a Ht- 

 tle pounded nitre or chlorate of Potassa, oxidates all the metals which 

 I have had an opportunity of examining. With the fused nitro muri- 

 ate or the triple mixture, when necessary, I satisfactorily dissolved 

 rhodium, platinum, iridium, gold, sulphuret of molybdenum, native 

 oxides of uranium, cerium and titanium, and crystallized chromate of 

 iron besides all the common metals and their ores. It is a remark- 

 able circumstance, however, that sulphur resists the action of these 

 very energic salts. It liquefies with them becoming deep red, but 

 does not appear to be otherwise affected, and the odor is that of sub- 

 limed sulphur, or its hydrate, without any resemblance to that of sul- 

 phurous acid. In no case was it found necessary to resort to a high- 

 er heat than that of a spirit flame. 



I cannot but regard these fused ammoniacal salts as capable of affor- 

 ding very valuable assistance to the mineralogist, in his operations 

 upon small portions of matter. They are, not only more portable than 

 the free acids, but far less liable to injure articles of dress or tarnish 

 instruments, and, although a large portion of the salts necessarily es- 

 capes by sublimation, the inconvenience is far less than that arising 

 from the copious fumes of free acids. 



Such indeed is the proper limit to their application, for, in the lab- 

 oratory, it will always be found far more convenient to employ the 

 common solvents. The best mode of using these salts, according to 

 my observation, is to rub together in a mortar, equal parts of sal-am- 

 moniac and nitre ; this mixture is to be heated upon a watch glass, 



Vol. XVIII.—No. 2. 33 



