Dr. Thomson — and his Answer 339 



converts veg£tuble blues into green. Its specific gravity is 

 0.590. Waterabsorbs 780 times its bulk of this gas, and is 

 converted into liquid ammonia. When this liquid is heated to 

 130°, the ammonia separates in the form of gas. When elec- 

 tric sparks are passed for a considerable time through dry am- 

 moniacal gas, its bulk is just doubled, and it is completely de- 

 composed. The new gaseous product consists of a mixture of 

 three volumes of hydrogen gas, and one volume of azoiic gas. 

 It is obvious from this, that ammonia is composed of three vo- 

 lumes of hydrogen, and one volume of azote, compressed into 

 two volumes. Hence its constituents by weight are — 



Hydrogen 0.2082 0.125x3 1 



■Azote ..0.9722 1.75 4f 



Thus we see that ammonia is a compound of three atoms of 

 hydrogen and one atom of azote. Hence the weight of an atom 

 of it is 2.125"— .Vol. 1. p. 224. 



" It (ammonia) may be procured in the foUowmg manner ; put 

 into a retort a mixture of three parts of quick-lime, and one part 

 of sal ammoniac in powder. Plunge the beak of the retort below 

 the mouth of a glass jar, filled with mercury. Apply the hpat 

 of a lamp to the retort; a gas comes over which displaces the 

 mercury, and fills the jar. This gas is ammonia. Am-.nonia 

 was altogether unknown to the ancients. Basil Valentine de- 

 scribes the method of obtaining it." " Dr. Priestley discovered 

 the method of obtaining it in a state of purity. Ammonia m 

 the state of gas, is transparent and colourless like air; its taste 

 is acrid and caustic, like that of the fixed alkalis, but not nearly 

 so strong, nor does it, like them, corrode those animal bodies to 

 which it% applied; its smell is remarkably pungent, though n.ot 

 unpleasant, when sufficiently diluted. Animals cannot breathe 

 it without death. Us specific gravity is 0.590, that of common 

 air beino- 1." " Water by my trials, is capable of absorbmg 

 780 times its bulk of this gas." " The term ammonia almost 

 always means this liquid solution of ammonia m water. When 

 heated to the temperature of 130°, the ammonia separates urjd.er 

 the form of gas." " When oxygen and ammoniacal gases are 

 mixed, the mixture may be fired by an electric spark, as was 

 first observed by Dr. Henry." " Dr. PrieslJy.discovered thatwlien 

 electric explosions are made to pass through this gas, its bulk 

 is gradually augmented to thrice the space which it formerly 

 oecupied, and a quantity of liydrogengas is produced." " Am- 

 monia then is composed of three volumes of hydrogen, and one 

 volume of azote, or which comes in this case to the same thing, 

 of three atoms hydrogen, and one atom azote. Hence its con- 

 stituents by weight are : ,,v- 



Hydrogen 0.125x3=0.375 100 



Azote 1.75 466.6 



