Chemistry. [Lecture 31. 



with a graduated stem. The instrument must be 

 nearly of the same specific gravity with the spirit. 

 The lower or higher it swims, the stronger or 

 weaker is the spirit. There are only three or 

 four spirits the precise strength of which it can 

 be of any consequence to know, as brandy, double 

 rum, and the strongest spirit of wine. If we have 

 a small glass ball for each of these, equal in spe- 

 cific gravity to them when of a proper strength, . 

 and use at the same time a thermometer, they 

 will answer for all seasons. The painters, who 

 use spirits of great strength, try them by kindling 

 a wick of cotton wetted with the spirit, observing 

 whether the wick is burned. If it is burned, they 

 judge the spirit strong ; because if it contained 

 water, it would remain with the wick, and pre- 

 vent its consumption. But this method is un- 

 certain ; for the burning of the wick depends a 

 good deal on the quantity of spirit, and the 

 manner of putting it on. 



It is also common to throw some grains of 

 gunpowder into the spirit: if they catch fire, 

 when' taken out, it is presumed no water is con- 

 tained in it, for it would attach itself to the pow- 

 der and prevent its explosion. 



Alcohol, when pure, consists entirely of car- 

 bon, hydrogen, and a quantity of water. By the 

 experiments of Lavostier, seventy-six grains of 

 alochol contained about twenty-three of carbon, 

 six of hydrogen, and forty-eight of water. In 

 its strongest state it is a colourless, subtile, pene- 



