46f WATBA Itf MtrRIATtt AClfc GAS. 



id far desiccated by exposure to potash, " as to shew no traces of 

 condensed moisture when exposed to a cold of 0° of Fahren- 

 heit," and this precaution of exposing the ammonia to heat 

 had been observed both in Sir Humphry's and in Dr. Hope's 

 experiment. His brother, he adds, has proved, that a minute 

 portion of solution of muriatic acid in water may be obtained 

 by intensely cooling the gas. Dr. Henry, however, found, that 

 muriatic acid gas, when freed from visible moisture, which it 

 is completely by exposure to muriate of lime, (a precaution 

 observed in the above experiments) deposits no water even when 

 cooled to 26 below 0° of Fahrenheit, and Gay Lussac not 

 only obtained the same result, but farther found no indication 

 of moisture from the action of fluo-boric gas, which is its most 

 delicate test. And, even according to Sir Humphry's statement, 

 the quantity of liquid deposited from 200 cubical inches at 7 5°, 

 cooled to 1 below 0, is not equal to ^ of a grain, and only 

 about half the weight of this is water. If any such water, 

 therefore, is taken up by the gas at 50°, and retained by it 

 after exposure to muriate of lime, of which there is no proof, 

 but the reverse, it may amount, in QO cubic inches, to ^ or -fa 

 of a grain. Lastly, Ihe mercury had been strained through 

 If the salt warm linen, and was perfectly dry. The gases, therefore, hav- 

 wmtCT*itwOttkl m S ^ )een suom ^ tte d carefully to processes which are known to 

 retain it, &c< render them free from all moisture, being transmitted through 

 dry mercury, and combined in an exhausted vessel, so that the 

 mercury never came into contact with the salt, there is not 

 the slightest reason to suppose a communication of water from 

 any extraneous source. It is an obvious reflection, too, that 

 if this salt is otherwise entirely free from water, as the new 

 hypothesis assumes, were a minute portion communicated to. 

 it, it must be retained, in conformity to the'law which univer- 

 sally regulates the combination of water with saline substances, 

 by a very powerful attraction, so that it could not be expelled, 

 and rendered sensible in such an experiment. And lastly, such 

 causes are assigned by Mr. J. Davy only as " tending to account 

 for the \ety minute quantity of water obtained" in his brother's 

 experiment. They are, of course, still less adequate to account 

 for the larger quantity in Dr. Hope's experiment -, and are 

 utterly incapable of accounting =for the much larger quantity 

 admitted by them to be obtained when the salt is heated in 



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