Notices respecting Ne'w Books, S81 



This letter contains also an account of an experiment upon which 

 its illustrious author most probably founded his opinion, now gene- 

 rally adopted, that oxymuriatic acid, as it was then called, is an ele- 

 mentary, or at any rate an undecomposed substance. " I have kept," 

 he says, "charcoal white-hot by the Voltaic apparatus, in dry oxy- 

 muriatic acid gas for an hour, without effecting its decomposition. 

 This agrees with what I have before observed with a red heat. It 

 is as difficult to decompose as nitrogen, except when all its ele- 

 ments can be made to enter into new combinations." The experi- 

 ments by which Davy demonstrated that oxymuriatic acid is an 

 undecomposed body, are detailed in various papers read before the 

 Royal Society. The changes thus effected in the views of chemists 

 have been the subject of discussion with respect to the parties with 

 whom they originated. " As to the claim of priority," Dr. Paris 

 remarks, *' which has been urged by several philosophers in favour 

 of the French chemists, Davy, in speaking of Gay-Lussac's paper, 

 published in the Annales de Chimie for July 1814, observes, that 

 < the historical notes attached to it are of a nature not to be passed 

 over without animadversion. M. Gay-Lussac states, that he and 

 M. Thenard were the first to advance the hypothesis that chlorine 

 was a simple body j and he quotes M. Ampere as having enter- 

 tained that opinion before me. On the subject of the originality of 

 the idea of chlorine being a simple body, I have always vindicated 

 the claims of Scheele ; but I must assume for' myself the labour of 

 having demonstrated its properties and combinations, and of having 

 explained the chemical phaenomena it produces ; and I am in pos- 

 session of a letter from M. Ampere, that shows he has no claims of 

 this kind to make*.' " 



Dr. Paris has we think settled the question by reference to printed 

 documents. " Davy published his < Elements of Chemical Philoso- 

 phy' in 1812, containing a systematic account of his new doctrines 

 concerning the combinations of simple bodies. Chlorine is there 

 placed in the same rank with oxygen, and finally removed from the 

 class of acids. In 1813 M, Thenard published 'the first volume of 

 his Traite de Chimie Elenientaire Theorique et Pratiqve,' in which he 

 states the composition of oxymuriatic acid as follows : — ' Composi- 

 tion. The oxygenated muriatic gas contains the half of its volume 

 of oxygen gas, not including that which we may suppose in muriatic 

 acid.' It was not until the year 18J6 that, by a note in his fourth 

 volume, he appears to have at all relaxed in his attachment to the 

 old theory of Lavoisier and Berthollet; and it will presently ap- 

 pear that at the period above mentioned, iodine had been disco- 

 vered, and its analogies to chlorine fully established, by the saga- 

 city of Davy." 



In his ninth chapter, Dr. Paris gives an account of Davy's " Ele- 

 ments of Chemical Philosophy," above alluded to, of various disco- 

 veries, and also of his work on Agricultural Chemistry. We cannot 

 afford room for any of the Doctor's remarks on these subjects, but 

 recommend them as well worth perusal. 



* Royal Institution Journal, vol. i. p. 28<i. 



Dr. 



