320 LETTEES ON NATURAL MAGIC. 



part of the wick became red-hot, and continued 

 so while a drop of alcohol remained, provided 

 the air in the room was undisturbed. On one 

 occasion the wick continued red-hot for twenty- 

 four hours, and a very disagreeable acid vapour 

 was formed. 



On these principles depend the lamp without 

 flame which was originally constructed by Mr. 

 Ellis. It is shown in the annexed figure, where 

 AB is the lamp, and h a cylindrical coil of plati- 



. 79. 



num wire, the hundredth part of an inch in 

 diameter. This spiral is so placed that four or 

 five of the twelve coils of which the cylinder 

 consists are upon the wick, and the other seven 

 or eight above it. If the lamp is lighted, and 

 continues burning till the cylindrical coil is red- 

 hot, then if the flame is blown out, the vapour 

 which arises from the alcohol will by its combus- 

 tion keep the coils above the wick red-hot, and 

 this red heat will in its turn keep up the vaporiza- 

 tion of the alcohol till the whole of the alcohol 

 is consumed. The heat of the wire is always 

 sufficient to kindle a piece of German fungus or 

 saltpetre paper, so that a sulphur match may at 



