210 On the Question, Whether Alcohol he a Product 



tained vinegar, — a proof he conceives that alcohol and extractive 

 had been carried off from the tun. 



May not the vinegar have been formed from a portion of ve- 

 getable matter dissolved in the carbonic acid, which the water 

 had imbibed, and which by dilution and other causes had ))a'ssed 

 at once into the acetous fermentation ? The supposition receives 

 countenance from a fact which I observed, namely, that the wa- 

 ter exposed to the gas has always the disagreeable smell of the 

 wash. 



It is well known to distillers, that a dense solution of sugar 

 will after a successful fermentation become much lighter than, 

 water. Without allowing that the diminution of specific gravity 

 is owing to the formation of alcohol, it will not be easy to account 

 for this fact. I have obtained tliis result even by operating oa 

 a few pounds of sugar. 



Wash after a complete fermentation w-ill be found capable of 

 becoming coloured by digestion on raspiu;:',s of the Pterocarpus 

 saw/aZin?/?, a wood which (as is well known) imparts no colour to 

 water, but readily to spirit. 



The attraction is so strong, and the mixture so uniform and 

 intimate, between the alcohol and the other ingredients of fer- 

 mented liquors^ that it is not easy to detach the former at once : 

 yet the attraction v»'ill be considerjibly weakened by subcarbo- 

 nate of potash. I mixed a few ounces of wash fermented at 

 56** with more of this salt than it could dissolve : the mixture 

 was made in a glass cylinder of which two-thirds remained 

 empty. When the vessel was strongly agitated, the stopper 

 taken out, and a burning taper introduced, a blue flame de- 

 scended to the surface of the liquor, precisely similar to the 

 burning vapour of alcohol. 



There were now strong presumptions that alcohol was really 

 present in the fermented liquor. If it could be obtained in the 

 insulated form without employing heat, it appeared to me that 

 the question was at an end. 



The opinion of Fabroni was, that at and much below the 

 boiling point the wine is decomposed, producing alcohol by a 

 new combination of its elements: so low a temperature as 1)4' 

 he supposed to be sufficient. To make an experiment as unex- 

 ceptionable as possible, I dissolved 3G troy ounces in 144 of 

 water, and to this while at 00° 1 added six ounces of active yeast. 

 I observed narrowly the commencement of fermentation ; and 

 when this took place, the vessel was immersed in cold water, 

 which caused the temperature to sink to 56". The process con- 

 tinued for ten day?, during which the heat never rose beyond 57^. 

 The fermentation being over, a small quantity of the wash was 

 mixed with ag much subcarbonate of potash as it could dissolve. 



The 



