USES OF WHAI,E-OIL. 433 



wlien the fault lies in those who have the charge of 

 the lamps in which it is consumed. Want of pro- 

 per cleanliness is a very common fault, and one 

 which is most inimical to the ohtaining of a good 

 light. It is a practice not uncommon with those 

 who use oil lamps, especially in kitchens, to fill the 

 lamp up, night after night, without removing the 

 residue, and cleaning it out, by which all the impu- 

 rities mechanically mixed in the oil are progressive- 

 ly deposited and concentrated, until the cavity of 

 the lamp becomes almost filled with a gross sub- 

 stance, of the consistence of common paint. Pure 

 oil, of the quality of some that T have myself pre- 

 pared, would no doubt continue to burn with a pro- 

 per effect, though the lamp were not cleaned out 

 for a month together, provided care were taken to 

 prevent the access of dust ; but, in the use of the 

 best oil of commerce, tlie lamps ought to be emp- 

 tied, and carefully cleaned out, at least once or twice 

 a-wcek. A common error, also, in the trimming of 

 lamps, consists in furnishing them with wicks of too 

 great diameter. The wicks should be so thick as 

 to prevent them from slipping down the tubes in 

 which they are supported ; but they shoidd by no 

 means fill the tubes, otherwise the course of the oil 

 is interrupted, and an inadequate supply afforded 

 for producing the requisite fiame. It is a precau- 

 tion which ought not to be neglected, to dry the 

 wick by a fire, before it is used. 



VOL. II. . E e 



