2gg. GHEMICAL LAMP. 



Defcription, &c. within, io prevent the oil from running out while the refervoir 

 chemicTuamp. '* F^^ '"^" '^* place. This lamp alfo Aides on the maia 

 brafs rod by means of a focket and thumb-fcrew. It rs 

 therefore eafy to bring it nearer, or to move it fa: ther, at 

 pleafure, from the velfel which may remain fixed; a circura- 

 liance which, independent of the elevation and the depreflion 

 of the wicks of the lamp, affords the advantage of healing the 

 ve0els by degrees afier they are duly placed, as well as of 

 augmenting or diminifliing ihe heat inftantly ; or for main- 

 taining it for feveral hours at a certain degree, without m the 

 leaft difturbing the apparatus fufpended over it. It may 

 therefore be ufed for producmg the very gentle heat neceflary 

 for the reclification of ethers, or the ftrong heat requifite for 

 diftilling mercury. 



The chief improvement of this lamp confifts in its power of 

 affording an intenfe heat by the addition of a fecond cylinder 

 added to that of the common lamp of Argand. This addi- 

 tional cylinder inclofes a wick of one inch and a half in dia- 

 nieler, and it is by this ingenious contrivance, which was 

 firft fuggefted to me by Mr. Webfter, that a double flame is 

 caufed, and more than three times the heat of an Argand's 

 lamp of the largeft fize is produced. This part of the con- 

 lirudion of the lamp is clearly (hewn in Fig. 2, which repre- 

 fents the concentric wick-holders of the lamp; the difiance 

 between the exterior and interior cotton is half an inch, the 

 circumference of the largeft wick is 4| inches, and that of the 

 fmaller two. Both the wick-frames are conneded by a fine 

 fcrew cut upon a piece of pinion-wire. 



Fig. 3. is a fedion of the concentric cylindrical tubes in 

 which the wicks move. 



The fuperior advantages of this lamp, above all others I 

 am acquainted with, confifts therefore in quickly producing, 

 if required, a very low as well as intenfe heat, and in regu- 

 lating its power inftantaneoufly ; by means of which the 

 operator may obferve a number of minute circumftances efTen- 

 tial to be known, but which cannot be noticed when the fame 

 procefs is carried on within a furnace. 



Ufe of the Lamp-Furnace. 

 From what has l)een (iated it is obvious, that this lamp may 

 be ufed for a variety of chemical operations, if conduded un- 

 tier the conditions here pointed out ; a few of which are — 



1. For 



