8o HISTORY OF CHEMISTRY. [LECTURE V. 



chloric acid and chlorine, by means of which they are able to 

 explain all their experiments. 51 According to them, hydro- 

 chloric acid is a compound of an unknown radical, muriaticum, 

 with oxygen and water; chlorine, on the other hand, is 

 anhydrous hydrochloric acid combined with more oxygen, or, 

 what amounts to the same thing, it is ordinary hydrochloric 

 acid minus hydrogen. On this hypothesis the above-men- 

 tioned experiment of the synthetic formation of hydrochloric 

 acid is easily explained. The other facts connected with 

 the matter can be explained on the same hypothesis in 

 just as logical a manner. It is true that the two French 

 philosophers exerted themselves fruitlessly in trying to give 

 direct proof of the presence of the supposed oxygen. It was 

 in vain that they passed hydrochloric acid gas over red-hot 

 charcoal : no change was observable, and this negative result 

 might well have led them to another explanation. 52 They 

 point out that the hypothesis that chlorine (oxygenated 

 muriatic acid) is a simple substance, and hydrochloric acid 

 its hydrogen compound could also serve as the basis for the 

 explanation of the observed facts; they prefer, however, to 

 adhere to the old view. 



Davy, who arrived, independently it would appear, at the 

 latter assumption, declares himself a decided adherent of it. 53 

 He lays great stress on the fact that it agrees with Scheele's 

 original idea, in accordance with which chlorine was dephlogis- 

 ticated hydrochloric acid ; and he tries to support this view by 

 means of new arguments and new experiments. He draws 

 attention to the fact that chlorine does not become converted 

 into hydrochloric acid by the removal of oxygen, but only by 

 treatment with substances containing hydrogen ; and, further, 

 that chlorine is a neutral substance, which, adopting the old 

 hypothesis, is not in agreement with Lavoisier's theory, since it 

 would then be necessary to assume that a substance indifferent 

 to litmus had been obtained from an acid by the addition of 



51 Mem. d'Arcueil. 2, 339 ; Bulletin de la Soc. Philomatique, No. 18, 

 May, 1809. 5 - Mem. d'Arcueil. 2, 357-358. 53 Ann. Chim. 76, 1 12 and 129. 



