148 AMMONIUM, CHLORIDE OF 



of magnesia and ammonia, -which separates, to sublimation ; but it would not appear 

 that any great advantage is derived from proceeding in this way, either pecuniary or 

 otherwise. 



Mr. Laming passes sulphurous acid through the gas liquor, and finally oxidises 

 the sulphite thus obtained to the state of sulphate, by exposure to the air. (Patent, 

 Aug. 12, 1852.) 



Michael's mode of obtaining sulphate of ammonia, patented April 30, 1 850, is as 

 follows : The ammoniacal liquors of the gas-works are combined with sulphate and 

 oxide of lead, which is obtained and prepared in the following way : Sulphuret of 

 lead in its natural state is taken and reduced to small fragments by any convenient 

 crushing apparatus. It is then submitted to a roasting.process, in a suitably arranged 

 reverberatory furnace of the following construction : The furnace is formed of two 

 shelves, or rather the bottom of the furnace, and one shelf, and there is a communica- 

 tion from the lower to the upper. The galena or sulphuret of lead, previously 

 ground, is then spread over the surface of the upper shelf, to a thickness of about 

 2 or 2J inches, and there it is submitted to the heat of the furnace. It remains thus 

 for about two hours, at which time it is drawn off the upper shelf, and spread over the 

 lower shelf or bottom of the furnace, where it is exposed to a greater heat for a 

 certain time, during which it is well stirred, for the purpose of exposing all the parts 

 equally to the action of the heat, and at the same time the fusion of any portion of it 

 is prevented. By this process the sulphuret of lead becomes converted partly into 

 sulphate and partly into oxide of load. This product of sulphate and oxide of lead 

 is to be crushed by any ordinary means, and reduced to about the same degree of 

 fineness as coarse sani It is now to be combined with the ammoniacal liquors, 

 when sulphate of ammonia and sulphuret and carbonate of lead will bo produced. 



The sulphate of ammonia is separated by treatment with water, and the residuary 

 mixture of sulphide and carbonate of lead is used for the manufacture of lead 

 compounds. 



Properties. The sulphate of ammonia obtained by either of the methods above 

 described is a colourless salt, containing, according to Mitscherlich, one atom of 

 water of crystallisation. It is isomorphous with sulphate of potash. 



It deliquesces by exposure to the air ; 1 part dissolves in 2 parts of cold water, 

 and 1 of boiling water. It fuses at 140 C. (284 F.), but at 280 C. (536 F.) it is 

 decomposed, being volatilised in the form of free ammonia, sulphite, water, and 

 nitrogen. 



For the other sulphates, the sulphites, and those salts which are but little used in 

 the arts and manufactures we refer to Watts's ' Dictionary of Chemistry.' 



Uses. The chief consumption of ammoniacal salts in the arts is in the form of 

 sal-ammoniac, the sulphate of ammonia being principally used as a material for the 

 manufacture of the chloride of ammonium. It may, however, be employed directly 

 in making ammonia-alum, or in the production of free ammonia by treatment with 

 lime. 



-aiWIttONIUTVI. (NH 4 ) The radical supposed to exist in the various salts of am- 

 monia. Thus NH 4 [(WH 4 ) 2 O] is the oxide, NH 4 CL the chloride, of ammonium. 

 Ammonium constitutes one of the best established chemical types. See FOBMUL;E, 

 CHEMICAL. 



.a.MlVIOTJ'Itnvi, CHLORIDE OF. Commonly called SAL-AMMONIAC. (Sal am- 

 moniac, Fr. ; Salmiak, Ger.) The early history of this salt is involved in much 

 uncertainty. It would appear that the sal ammoniacus (&Xs oju/iwi/ja/cJj) of the ancients 

 was, in fact, rock salt. The earliest knowledge of the compound has been claimed 

 both for the Arabians and the Egyptians ; but the late Dr. Royle remarked, that ' the 

 salt must have been familiar to the Hindoos ever since they have burnt bricks, as 

 they now do, with the manure of animals, for some may usually be found crystallised 

 at the unburnt extremity of the kiln.' 



This salt is formed in the solid state by bringing in contact its two gaseous consti- 

 tuents, hydrochloric acid and ammonia. The gases combine with such force as to 

 generate, not only heat, but sometimes even light. It may also be prepared by mix- 

 ing the aqueous solutions of these gases, and evaporating till crystallisation takes 

 place. 



When ammoniacal gas is brought into contact with dry chlorine, a violent reaction 

 ensues, attended by the evolution of heat and even light. The chlorine combines 

 with the hydrogen to produce hydrochloric acid, which unites with the remainder of 

 the ammonia, forming chloride of ammonium, the nitrogen being liberated. The 

 same reaction takes place on passing chlorine gas into the saturated aqueous solution 

 of ammonia. 



Manufacture of Chloride of Ammonium from Camels' Dung. In Egypt which un- 

 doubtedly was the groat seat of the manufacture of this salt from the beginning of 



