AMMONIA. 139 



chloride has also been found as a sublimate arising from the combustion of coal 

 strata. Salts of ammonia exist in plants, but to a much greater extent in the liquid 

 and solid excrements of some animals. As a urate it forms the chief constituent of 

 the excrement of the boa, as well as that of many birds : hence the largo quantity of 

 ammoniacal salts in guano. See GUANO. 



In the guano deposits of South America large quantities of bicarbonate have been 

 met with and exported to Europe. In several manufacturing processes ammonia is 

 generated as in the purification of caustic soda, by heating it with nitrate of soda, 

 and possibly in this process in sufficient quantity to pay for condensation ; but of all 

 sources of supply the so-called ' ammoniacal liquor ' of the gas-works is the most 

 important. This is produced during the dry distillation of coal for the manufacture 

 of illuminating gas, and consists mainly of an aqueous solution of sesquicarbonato of 

 ammonia with some sulphide and sulphocyanide of ammonium, &c. 



Formation of Ammonia. No process has yet been devised for inducing the direct 

 combination of nitrogen and hydrogen to produce ammonia ; but under the disposing 

 influence of the production of other compounds, in the presence of these elements, as 

 well as when these gases are presented to each other in the nascent state, their union 

 is effected. 



Thus, when electric sparks are passed through a mixture of nitrogen and oxygen 

 in the presence of hydrogen and aqueous vapour, nitrate of ammonia is generated. 

 If, while zinc is being dissolved in sulphuric acid, nitric acid be added, much am- 

 monia is formed (Nesbit) ; so again, if hydrogen and binoxido of nitrogen be passed 

 over spongy platinum, torrents of ammonia are produced, the hydrogen converting 

 the oxygen of the binoxide into water, when the nitrogen, at the moment of its 

 liberation, combines with the hydrogen to form ammonia. 



It has even been proposed to carry out this last method on a manufacturing 

 scale. 



Messrs. Crane and Jullien, in their patent of January 18, 1848, describe a method 

 of manufacturing ammonia in the state of carbonate, hydrocyanate, or free ammonia, 

 by passing any of the oxygen compounds of nitrogen, together with any compound 

 of hydrogen and carbon, or any mixture of hydrogen with a compound of carbon or 

 even free hydrogen, through a tube or pipe containing any catalytic or contact sub- 

 stance, as follows : Oxides of nitrogen (such, for instance, as the gases liberated in 

 the manufacture of oxalic acid), however procured, are to be mixed in such pro- 

 portion with any compound of carbon and hydrogen, or such mixture of hydrogen 

 and carbonic oxide or acid as results from the contact of the vapour of water with 

 ignited carbonaceous matters, and the hydrogen compound or mixture containing 

 hydrogen may be in slight excess, so as to ensure the conversion of the whole of the 

 nitrogen contained in the oxide so employed into either ammonia or hydrocyanic 

 acid, which may be known by the absence of the characteristic red fumes on allowing 

 some of the gaseous matter to come in contact with atmospheric air. The catalytic 

 substance which Messrs. Crane and Jullien prefer is platinum, which may be in the 

 state of sponge, or it maybe asbestos coated with platinum. This catalytic substance 

 is to be placed in a tube, and heated to about 600 F., so as to increase the tempera- 

 ture of the product, and at the same time prevent the deposition of carbonate of 

 ammonia, which passes onwards into a vessel of the description well known and 

 employed for the purpose of condensing carbonate of ammonia. The condenser for 

 this purpose must be furnished with a safety pipe, to allow of the escape of uncon- 

 dnsed matter, and made to dip into a solution of any substance capable of combining 

 with hydrocyanic acid or ammonia where they would be condensed. A solution of 

 salt of iron is preferable for this purpose. 1 



Chemical Characters. The gaseous ammonia liberated from its salts by lime (in a 

 manner to be afterwards described) is a colourless gas of a peculiar pungent odour. 

 It is composed, by weight, of 1 atom of nitrogen and 3 of hydrogen ; or, by volume, 

 of 2 measures of nitrogen and 6 of hydrogen, condensed to four ; and may be 

 resolved into these constituent gases by passing over spongy platinum heated 

 to redness, or by a current of electric sparks. By a pressure of 6 '5 atmospheres at 

 50 F., it is condensed into a colourless liquid. It is combustible, but less so than 

 hydrogen on account of the incombustible nitrogen which it contains ; but its inflam- 

 mability may be readily seen by passing it into an argand gas flame reduced to a 

 minimum. 



Ammonia is very soluble in water, water at 32 F. absorbing no less than 1,149 

 times its volume of this gas, and at 68 681*8 times its volume ; and the solution has 

 a less density and a lower boiling point than pure water. The following Table 

 of the density of solutions of ammonia in water, of different strengths, is by Dr. 

 Ure: 



1 Pbarm. Journ. xiii. 114. 



