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XLIV. Remarks on Fermentation. By John Murray, Esq^. 

 KL.S. M.PV.S..^c. 



To the Editors of the Philosophical Magazine and Journal. 



Nailsworth, March 5, 1823. 



IN your Number for January last, we are infoi'med that 

 Messrs. Deurbroucq and Nichols have taken out a patent 

 for INIadame Gervais' new method of fermentation ; namely, 

 that of fermenting in close vessels. 



I have been in the practice of recommending fermentation 

 on this principle for several years with the superadded advan- 

 tages of conducting the process under the influence of a les- 

 sened or increased pressure on the surface of the fermenting 

 mass, in order to check or accelerate the process as may be 

 required by circumstances and season, because I had found 

 experimentally that fermentation moved with an accelerated 

 progress under an attenuated pressure of the atmosphere, and 

 that an increased density checked and retarded it. 



Hence I recommended fermenting in close vessels with the 

 air-pump applied. The piston rod posited horizontally, at- 

 tenuated the superincumbent pressure, and when it moved in 

 the vertical plane, an additional density was acquired. It is 

 now three years ago since this was carried into effect on my 

 recommendation, by Mr. Buchannan, a respectable brewer 

 of St. Ninian's, Stirlingshire. On these principles, it is evi- 

 dent that a violent and rapid fermentation might be checked 

 in summer, and a too tardy one accelerated in winter. 



As to the syphon applied to the fermenting vat, it had 

 long, I know, been so, successfullj', attached to the cask in the 

 case of domestic wines, by Mr. Blunt, an ingenious and intel- 

 ligent chemist of Shrewsbury, and on my recommendation 

 applied by the cyder manufacturer with success. 



It appeared to me to be of some consequence to ascertain 

 whether it might be advantageous to retain the carbonic acid 

 gas developed in fermentation, or suffer its entire expulsion. 

 Mr. Charles Spurrell, connected with the establishment of 

 Messrs. Barclay, Perkins and Co., made, at my particular re- 

 quest, the following experiment : — Half a bottle of mild porter 

 was filled with carbonic acid gas from the fermenting guile, 

 and a similar experiment made with table beer. These were 

 placed in a cellar by the side of full bottles of the same beer 

 and porter ; all hermetically sealed. They were examined at 

 the end of 13 months. Those with carbonic acid gas and 

 only half full, were very mild and pleasant, without any ten- 

 dency whatever to acidity, while the others were considerably 

 acid and otherwise unpleasant to the palate. 



The 



