104- PROPERTIES 01 ALCOHOL OR PURE SPIRIT OF WINE. 



Thermometers designed to indicate very low temperatures, was 

 illustrated by reference to the Alcohol Thermometers employed 

 by Captain Parry, during his winterings, in Prince Regent's 

 Inlet^ and Melville Island. The cold produced by the rapid 

 evaporation of alcohol was shown by referring again to the 

 pulse-glass (exhibited before in illustration of the subject of 

 ebullition), in the cold felt by the hand which held that bulb 

 of the instrument from which the evaporation took place. The 

 colours communicated to the flame of alcohol by various saline 

 substances were exhibited, as well as those substances them- 

 selves; its use in chemical lamps, on account of its giving no 

 soot when burnt, was mentioned and experimentally illustrated, 

 together with the great heat of its flame, as evinced by the ig- 

 nition in it of solid bodies, and the phenomena of its slow 

 combustion (without flame) on platinum wire. The history 

 of alcohol was then terminated by the statement of its chemi- 

 cal composition, it being regarded (agreeably to the opinion of 

 Gay-Lussac,) as a combination of olefiant gas (the nature of 

 which was illustrated by reference to the gas obtained from 

 oil for the purpose of illumination, and which contains a 

 large proportion of olefiant gas) and water, the separate ele- 

 ments of both, however, being also stated, thus : 



ALCOHOL IS COMPOSED OF 



1} 



23 



The Course was concluded by an account of the further 

 change, which, under certain circumstances, takes place in 

 the arrangement and relative proportions of the substances 

 which compose sugar and alcohol, terminating in the produc- 

 tion of Vinegar from them. The manufacture of vinegar from 

 vinous liquors, and the phaenomena which take place during 

 that process were described ; it being stated, that, although 

 carbonic acid is evolved during the process, as in the vinous 

 fermentation, "in that case, both the carbon and the oxygen 

 composing the carbonic acid are derived from the sugar in the 

 fermenting liquor ; while in the process we are now consider- 

 ing, called the acetous fermentation, the carbon only is given 

 out by the liquor, the oxygen being obtained from the air. 

 It is on this account that while sugar is converted into Alcohol 

 in close vessels, or at least in vessels which do not freely com- 



