Royal Society. 316 



liquors owe some of their valuable qualities to peculiar products 

 formed during fermentation. 



In order to trace the various chemical changes which occur in 

 this part of his research, the author has had recourse to numerous 

 experiments, the details of which are recorded in tabular forms. 

 The first table exhibits the analysis of different kinds of sugar, honey, 

 treacle, grape-juice and extract of malt and hops, the general result 

 of which is that all these compounds contain oxygen in excess above 

 the proportion in which it exists in water, and that they also con- 

 tain a small quantity of nitrogen. He shows, by two independent 

 modes of experimenting, that these bodies, when in solution, can- 

 not be the only compounds undergoing decomposition during that 

 fermentation, which has for its product spirit and carbonic acid; and 

 in proof of this proposition he recapitulates the different elements 

 in the compounds at the commencement and at the conclusion of 

 the experiments. He finds that when the proximate elements are 

 made the subject of calculation, the weight of the alcohol (consti- 

 tuted of two equivalents of carbon, three of hydrogen and one of 

 oxygen) added to that of the carbonic acid and undecomposed sugar, 

 exceeds the weight of the sugar employed by about 7 per cent. 

 On recapitulating the ultimate elements, he finds that the hydro- 

 gen and the oxygen in the compounds after the fermentation ex- 

 ceed their quantity in the sugar experimented upon, by 15 per cent, 

 of the former, and nearly 14 per cent, of the latter ; and as a proof 

 that no material error is occasioned by the mode of experimenting, 

 it is found that the difference between the quantity of carbon at the 

 first and at the last is very small. 



Having arrived at these conclusions, the author infers from his 

 experiments that the water of solution is decomposed by the carbon 

 of the dissolved vegetable matter, in every case of the vinous fer- 

 mentation, and in proportions proximately represented by the fol- 

 lowing formulae : viz. 



2 equivalents of the carbon of sugar 6-12 12-24 ?,.„. ^ipfiant o-a<, 



2 equivalents of the hydrogen of the water 1- 2- J ^^ ^* oienant gas. 



1 equivalent ofthe carbon of the sugar... 6-12 6-12 J 2-12 carbonic acid. 



2 equivalents of the oxygen of the water... 8- 16' J 



This decomposition he conceives is brought about by the influence 

 of nitrogen, a very small quantity of which enters into the constitu- 

 tion of the olefiant gas, forming the base of all spirituous fluids of 

 the alcohol and ethereal kind ; and thus each compound experi- 

 mented upon, forms these products in proportion to the quantity of 

 carbon which undergoes chemical change, whether that compound 

 be sugar, soluble parts of malt, grape-juice, or any other body. 



The author proceeds to inquire into the constitution of the pro- 

 ducts which result from this chemical action. He finds the gas 

 which is given off to be composed of carbonic acid, mixed with a 

 small proportion of carburetted hydrogen; and the spirit, when sub- 

 jected to careful analysis, to resolve itself into carbonic acid, water, 

 and a very small proportion of nitrogen : and in further proof of 

 the existence of this last- mentioned element in spirit, the author 



