338 Aiuilysis of Scientific Books. 



only over mercury. No combustible body will burn in it; and 

 it destroys life instantly, when an attempt is made to breathe it." 

 " Its specific gravity is the mean of that of chlorine and hydrogen, 

 or 1.2847. Hence 100 cubic inches of it weigh 39.162, grains 

 It constituents are as follows : 



Hydrogen 0.125 1 



Chlorine 4.5 36." 



The above is found at pp. 221 and 222 of Vol. 1st. In 

 volume 2d, we have the following, at page 247. 



" When equal voliunes of chlorine and hydrogen gas are 

 mixed together, if the mi.vture be exposed to the direct rays of 

 the sun, or if an electric spark be made to pass through it, an 

 explosion takes place, the two gases combine without any change 

 of bulk, and are converted into muriatic acid gas. Hence mu- 

 riatic acid is a compound of equal volumes of the two gases, or 

 it is composed by weight of 



Hydrogen 0.125 1 



Chlorine 4.5 36." 



*' Since the composition of muriatic acid has become known, 

 Gay-Lussac has thought proper to give it the name of hydro- 

 chloric acid, in order to pointoutits composition." " Itpossesses 

 the following properties. It is invisible, like common air, and 

 capable, like it, of indefinite contraction and expansion. Its 

 smell is peculiar. It reddens vegetable blues, and has a very 

 sour taste. Its specific gravity is 1.2847, that of common air 

 being I. Animals are incapable of breathing it; and when 

 plunged into jars filled with it, die instantaneously, in convul- 

 sions. Neither will any combustible burn in it. If a little water 

 be let up into ajar, filled with this gas, the whole gas disappears 

 in an instant, the mercury ascends, fills the jar, and pushes the 

 water to the very top. Hence the necessity of making experi- 

 ments with this gas over mercury." Vol. II. p. 243 and 244. 



Let us look next to Ammonia. " This substance was un- 

 known to the ancients. The method of obtaining it, is de- 

 scribed by Basil Valentine. If this salt (carbonate of ammonia) 

 or sal ammoniac, be mixed with twice its weight of quicklime, 

 put into a flask, and exposed to the heat of a lamp, a gas comes 

 over, which must be received over mercury, and which is am- 

 moniacal gas. This gas was first discovered by Dr. Priestley." 

 " Ammoniacal gas is transparent, and colourless, and possesses 

 the mechanical properties of air. Its smell is very pungent, 

 though rather agreeable when sufficiently diluted. Its taste is 

 acrid and caustic, and if drawn into the mouth, it corrodes the 

 tkin. Animals cannot breathe it without death. When mixed 

 with oxygen gas, and an electric spark passed through the mix- 

 ture, it detonates as was first discovered by Dr. Henry. It 



