i6o Management of Light in Illumination. 



of lamps by preparing their wicks, and prepared wicks 

 have been sold at high prices ; but the secret of the 

 preparation has not to my knowledge been made 

 public. 



Having purchased some of these prepared wicks 

 several years ago at Munich, from an itinerant Italian 

 pedlar, I analyzed them. On exposing them to heat, 

 I separated from them a substance which had every 

 appearance of being pure tallow, but to which a strong 

 and not disagreeable scent had been given, probably 

 to conceal the secret of the preparation, which I then 

 considered as being a mere cheat, and paid no farther 

 attention to it. Some time after, on considering the 

 matter more attentively, I found reason to conclude 

 that either tallow or wax, heated very hot, might very 

 probably be used with advantage for preparing wicks 

 for lamps, and also for candles. I can explain my ideas 

 on that subject in a very few words. 



In order that a lamp or candle may burn well, it is 

 necessary that the oil, tallow, or wax which supplies 

 the combustion, should flow freely over the surface of 

 those minute fibres of the cotton which compose the 

 wick. 



Every extraneous body, whether solid or fluid, which 

 remains attached to the surface of those fibres, must 

 necessarily prevent the oil, tallow, etc., from flowing 

 freely over them. 



Now it is most certain that a considerable quantity 

 of air, and also of water (moisture), remains attached to 

 the cotton wicks of lamps for a long time after they 

 have been immersed in oil. This may easily be made 

 to appear by exposing the oil with the wick in it under 

 the exhausted receiver of an air-pump, for the surface 



