288 Dr. Ure on Mioiatir Acid, &c. 



silver, which, from the above-recited experiments, represent 

 39.675 of chlorine ; the quantity, therefore, present in 100 grs. of 

 acid, at the density of 1.200. If to 39.675 we add one prime 

 equivalent of hydrogen =:J-.9j|^-^= 1.1021, the sum 40.7771 will 

 represent the corresponding quantity of muriatic acid gas. Hence, 

 for ordinary practice, if we estimate in round numbers, the value 

 of liquid acid, specific gravity 1.20, at 40 per cent, of chlorine 

 and 41 of muriatic gas, we shall commit no error of consequence. 

 The correspondence between the above experimental results, 

 and those given by Sir H. Davy in his valuable Elements of 

 Chemistry, is almost exact, though the two methods are suffi- 

 ciently distinct. Sir H. and Mr. E. Davy found that 47.25 

 grains of water at 43° Fahr. barom., 30.2 absorbed 34.8 grains 

 of gas, and formed a solution of specific gravity 1.21 ; and the 

 whole precipitated by nitrate of silver, afforded about 132 grs. 

 of dry horn silver. Again 57.5 grains of water, at 44°, barom. 

 being 30.1, gained nearly 38 grains by absorbing acid gas, and 

 formed a solution of specific gravity 1.2*. The only other 

 point which they determined by experiment was for the specific 

 gravity 1.114. Let us compare a little their direct experiment 

 of condensing the gas in water (whose result agrees very nearly 

 with mine,) with their result from chloride of silver. If 82.05 

 grains of acid of 1.21 resulted from the combination of 47.25 

 water -f34.8 acid gas, then 100 of such acid, at 43°, should 

 contain just 42.41 parts, as given in their table. But if we 

 calculate the acid gas present in the same 82.05 grains of li- 

 quid acid, from the weight of horn silver which they obtained, 

 we shall have a considerably different result. Naming the 

 equivalent of chloride of silver, 18.375(4.5-1-13.875) we shall 

 have this proportion ; 18.375 : 4.5; ; 132 : 32.7 of chlorine, cor- 

 responding to 33.225 of acid gas, instead of 34.8, as by their 

 direct experiment. If, with Dr. Thomson, we call chloride 

 of silver 18.25 (13.75-J-4.5), then we have the proportion 

 18.25 : 4.5:: 132 : 32.548 of chlorine, or 33.452 of muriatic 

 gas. Finally, by Dr. Wollaston's scale, 132 grains of muriate 



* Elements, p. 252, Note.. 



