122 On Sir H. Davy's Theory of [Aug. 



be about the number of pounds that are worth 100 guineas. 

 Thus, for good Lioneza, n. 25, 25 x 25 — 325 = 300, giving "Js. 

 a pound ; for moderate South Down, n. 35, 35 x 35 — 300 = 

 900, or 25. 4d. a pound : which is probably about the proportional 

 value, though both the proportional and the real values must 

 fluctuate according to the demand of the manufacturer. 



(To be continued.) % 



Article X. 



Cn Sir H. Davy's Theory of Chlorine, and its Compounds. By 

 Mr. William Henderson, Member of the Royal Medical 

 Society of Edinburgh. 



(Continued from p. 13.) 



II. Oxymariatie Gas, ly its Action on Metals and Inflammables, 

 produces Substances differing essentially from the Oxides of' 

 the same Bodies. 



The new theory was, until very lately, secure from assault on 

 this quarter ; for except two passages in the Philosophical 

 Transactions, nothing definite had been advanced respecting this 

 point by its; supporters. These passages I insert : — 



" Muriatic acid gas, as I have shown, and as is farther proved 

 by the researches of MM. Gay-Lussac and Thenard, is a com- 

 pound of a body unknown in a separate state, and water. The 

 water, I believe, cannot be decompounded, unless a new com- 

 bination is formed; thus it is not changed by charcoal ignited 

 in the gas by voltaic electricity ; but it is decompounded by all 

 the metals ; and in these cases hydrogen is elicited, in a manner 

 similar to that in which one metal is precipitated by another, the 

 oxygen being found in the new compound." * 



" In some experiments, made very carefully by my brother, 

 Mr. John Davy, on the decomposition of muriatic acid gas by 

 heated tin and zinc, hydrogen equal to about half its volume was 

 disengaged, and metallic muriates, the same as those produced by 

 the combustion of tin and zinc in oxymuriatic gas, resulted. "f 



These two authorities are in very positive terms ; and if they 

 are to be relied on, the products of the «ction of oxymuriatic 

 gas on metals, though not similar to those which result from the 

 action of oxygen on the same bodies, are precisely what they 

 were thought to be, viz. compounds of the metals and oxygen, 

 with which the muriatic acid, condensed from the want of 



* Phil. Trans, 1810, p. 67. + Phil. Trans. 1810, p. 237, 



