Alcoholic Fluids, Oils, S^-c. m Lamps. 59 



that is the usual yellowish white, flame reappears. On the same 

 principle, a wine-glass full of oil may be made to exhibit either 

 a blue flame, covering the whole surface of the oil, or a flame of 

 a blue and white colour. 



When diluted alcohol, vulgarly termed ardent or proof spi- 

 rit, is burned in a lamp without a wick, the colour of the flame 

 is blue, or blue and white, similar to the flame of alcohol former- 

 ly described. In this case, a simple distillation and combustion 

 goes forward ; the whole of the water being separated as cold, 

 or nearly as cold, as before its passage through the flame ; and 

 the burner only acquires a perceptible increase of temperature. 

 The flame has a fine conical form, and the combustion proceeds 

 without any buzzing noise. Hence the advantage of a lamp, 

 without a wick for burning diluted alcohol, such as the whisky 

 of the shops. When that fluid is burned in the usual way with 

 a wick, there is, with other disadvantages and peculiarities to 

 be mentioned, this great inconvenience, that if, after the com- 

 bustion has continued a short time, the flame be extinguished, 

 it cannot be relighted without renewing the wick. Besides, by 

 using a glass burner, there is derived all the advantage of a spi- 

 rit-lamp without the expence ; and ardent spirits can readily be 

 had in situations where alcohol cannot be procured. 



When diluted alcohol is burned with a wick, the flame is not 

 blue and white, as when a slow conducting tubular burner is 

 made use of; on the contrary, much yellow light is given out; 

 the white disappears, and a portion at the base has a blue co- 

 lour. The form of the flame is mucji less regular ; it has a dis- 

 agreeable flickering motion, and the combustion is accompanied 

 by a constant whizzing or buzzing noise. But, with all this difi*e- 

 rence of effect resulting from the mode of combustion, the wick 

 undergoes no change, being in no degree carbonized by the 

 flame. In this case there is a cotemporaneous vaporization and 

 combustion of the alcoholic part of the fluid ; but the watery 

 part is not separated as in the lamp without a wick. Part of 

 the water is converted into steam, and part of it remains in the 

 wick; which last circumstance prevents the relighting of the 

 lamp, after a short continuance of combustion, as formerly men- 

 tioned. Though the wick remains uninjured by the flame, it 

 always becomes hot ; and hence not only alcoholic vapour, but 



