352 MM. Welter and Gay-Lussac on a neiv Acid [Nov. 



oxide of lead in the glass. In the experiments of which I have 

 given an account (Edinburgh Transactions, vol. viii. p. 301), I 

 found that exposure to a heat, not so high as that of ignition, is 

 not necessary to obtain water from the action of metals on 

 muriate of ammonia ; one much more moderate, and at which 

 no action on the glass can be supposed to be exerted, is suffi- 

 cient ; and accordingly, not the slighest indication of the glass 

 being acted on, can be perceived. In obtaining, for example, 

 water from a mixture of tin filings and muriate of ammonia, 

 heated in a retort by the gentle heat of a small lamp, the retort 

 remains perfectly unaltered in colour, transparency, and lustre. 

 These objections then I regard as of no force. At the same 

 time I do not consider the discussion as of much importance. 

 The view which I have now proposed of the nature of muriatic 

 acid does not rest on any exclusive proof of water being obtained 

 from it but on other grounds. And it is quite sufficient that it 

 yields water in the same cases of chemical action, in which other 

 powerful acids, as the sulphuric, nitric, and oxalic, afford it ; 

 while the sulphurous and carbonic afford none. The same 

 theory applied to the constitution of the former will fall with 

 every probability to be applied to that of muriatic acid ; and 

 whatever superiority may belong to it, this will be applied to both. 

 The question, therefore, deserves attention only on the principle 

 that in chemical investigations it is always of importance to 

 adhere rigidly to the observation and strict expression of a fact 

 whether it is conformable to a prevalent doctrine or not, or 

 whether it admits of obvious explanation or not on any esta- 

 blished law. In numerous experiments on muriatic acid gas, I 

 have always obtained water in small but very sensible quantity, 

 where its production, I am satisfied, cannot be accounted for 

 from any of the extraneous sources to which it has been 

 attempted to refer it. And I certainly shall not refrain from 

 maintaining what I regard as the strict expression of an experi- 

 mental result. At the same time, in the experiment at present 

 referred to, the formation of a supermini ate affords a principle 

 which, as I have already stated, sufficiently accounts for the> 

 fact. 



Article V. 



On a new Acid formed of Sulphur and Oxygen.* 

 By MM. Welter and Gay-Lussac. 



The acid, which constitutes the subject of this memoir, lies, 

 as far as the proportion of its elements is concerned, between 



* The origin of this acid is as follows: While M. Welter managed a bleaching 

 work, he made sulphurous acid to ixct upon the black oxide of manganese, which. 



