236 On the Nature of Muriatic Acid. [Oct. 



proves nothing in favour of the new. Though the muriate of 

 water has the gaseous form, this proves nothing against the old 

 hypothesis ; for the form of aggregation is a physical property 

 which neither hypothesis is capable of explaining. 



The strongest circumstance in favour of the new hypothesis is, 

 that charcoal is neither capable of decomposing oxymuriatic gas 

 nor muriate of silver at any temperature whatever. This cir- 

 cumstance, compared with the extreme facility with which 

 oxymuriatic gas acts upon the metals, appears at first sight per- 

 fectly tojustify the conjecture that oxymuriatic gas is an elemen- 

 tary substance ; but the most simple explanation is not always the 

 most accurate. In order to conceive the cause of this pheno- 

 menon we must attend to its connection with the general theory 

 of chemistry. We must observe, in the first place, that there 

 are several acids which cannot exist without being combined with 

 water or with some other oxide; such as sulphuric, nitric, oxalic, 

 tartaric acids, &c. Now we suppose that the same is the case 

 with muriatic acid; and if so, a combustible body, the oxide of 

 which formed by the quantity of oxygen contained in the oxymu- 

 riatic gas is insufficient to saturate all the quantity of muriatic 

 acid contained in that gas, can never at any temperature what- 

 ever decompose oxymuriatic gas into oxygen and muriatic acid, 

 because the muriatic acid has no base with which it can combine 

 in order to preserve its existence as an acid. Such a combustible 

 substance must either deprive the acid radicle of the whole of its 

 oxygen, or, if its affinity for oxygen be not sufficiently great for 

 that, it will leave the acid without any alteration at all ; but we 

 know that the oxide of carbon has not the property of combin- 

 ing with any other oxide. Hence charcoal cannot furnish an 

 oxide capable of uniting with muriatic acid, when deprived of 

 its excess of oxygen. If we suppose that the radicle of muriatic 

 acid has a stronger affinity for oxygen than charcoal has, thera 

 is no difficultv in explaining the want of action of charcoal on 

 oxymuriatic acid ; while such a supposition throws considerable 

 light on the theory of chemistry. 



You see, then, that the facts which have been considered as 

 most favourable to the new hypothesis are equally explicable on 

 the old opinions. 



If we attempt to prove by a direct experiment that the new 

 theory is inconsistent with truth, it will be difficult to find 

 any which is not susceptible of explanation, according to either 

 supposition. The cause of this is, that as the muriatic acid 

 cannot be obtained in a separate state, it always retains in com- 

 bination enough water to oxydate the combustible bodies suffi- 

 ciently to be capable of uniting with the pure acid. Hence we 

 have it not in our power to make potassium act upon pure 

 muriatic acid : because, whether we employ oxymuriatic gas or 



