BETWEEN MURIATIC ACID AND CHLORINE. 349 



5. When strongly calcined charcoal was employed, I obtain- 

 ed no traces of water at all. It will, moreover, be readily 

 granted by every chemist, that, from the equivocal nature of 

 common charcoal, as prepared with greater or less care, and 

 from the uncertainty of expelling the whole gaseous matter, 

 and moisture it so greedily imbibes, no important inference 

 can be drawn from any results in which it is concerned *. 



The traces of moisture which Dr Murray observed in his 

 experiments, must have been the adhering or hygrometric wa- 

 ter of the sal ammoniac. He has indeed assigned some hypo- 

 thetical reasons, why sal ammoniac ought not to attract mois- 

 ture from the air. I shall confront them with the results of 



experiments 



* If mere heat can separate the combined water of sal ammoniac, then the 

 salt, which, after passing through ignited quartz, has concreted on the verge of 

 ignition, being nearly anhydrous, will', in an equal weight, contain more aeid 

 than before transmission. It will in fact bear the same relation to common sal 

 ammoniac, that ignited sulphate of soda does to the crystallised salt. Having 

 transmitted, in the state of vapour, the salt condensed from the dry gases 

 through ignited quartz, I took 10 gr. of the cake, consolidated just beyond the 

 quartz ; and dissolving them in water, decomposed by nitrate of silver, when I 

 obtained 27 gr. of dry muriate of silver, being the quantity precisely equivalent 

 to 10 gr. of ordinary muriate of ammonia. (See Woll. Scale of Chem. Equiv.) 

 Hence it is evident, that ignited sal ammoniac has undergone no change in its 

 constitution. There was obtained one-tenth of a grain of liquid in that experi- 

 ment, in which 20 gr. of salt had been passed through the quartz ; but this 

 though colourless rock-crystal, betrayed the presence of iron in its composition. 

 For, the liquid stained the paper on which it was withdrawn, of a yellow colour ; 

 and the sublimed salt had, faintly, the same hue. The resulting muriate of sil- 

 ver partook, a little, of the brown tinge, of peroxide of iron. I therefore ascrib- 

 ed the production of liquid to the action of the oxide of iron on the hydrogen of 

 the ammonia. 



