Mr. E. Solly 07i a Chemical Lamp-Furnace, 191 



steady, uniform heat to a platinum vessel, sufficiently high to 

 effect the ready fusion of vitreous substances by means of a fuel, 

 free from those objections attending the use of one containing 

 solid carbonaceous matter. Mr. Harcourt's furnace consisted 

 of a number of jets arranged round the crucible to be heated, 

 which, to ensure uniformity of temperature, was suspended by 

 three platinum wires from a watch movement, which caused 

 it to rotate slowly on its vertical axis ; the fuel employed was 

 hydrogen, generated in a strong iron reservoir, and burnt 

 under a pressure of from 10 to 30 atmospheres. The me- 

 chanical arrangements of this lamp-furnace were very beau- 

 tiful, and the heat produced by the combustion of the jets of 

 compressed hydrogen directed against the bottom and sides of 

 the revolving crucible was steady, intense, and apparently 

 manageable; but the instrument was of course very expensive, 

 and required considerable care in its use. 



The exhibition of this apparatus suggested to me the pos- 

 sibility of constructing a lamp on a similar principle, but far 

 less expensive, and sufficiently simple for ordinary use ; which, 

 though it might not afford so high or pure a source of heat 

 as the arrangement of Mr. Harcouit, might yet constitute a 

 useful instrument in the laboratory : as, on trial, I found my 

 plan perfectly successful, I am led to think that a brief de- 

 scription of the lamp will be interesting to others. 



It is well known that when coal-gas is mixed with a certain 

 proportion of air it burns with a pale blue flame containing 

 no solid carbon, and therefore giving only a very feeble light, 

 but possessing a very high temperature, so much so, that the 

 large pale flame of gas mixed with air and bui'nt above a 

 diaphragm of wire gauze is very commonly employed when 

 a higher temperature is required than can be obtained by 

 the mere use of an Argand lamp. It appeared probable, after 

 seeing Mr. Harcourt's lamp, that a very high temperature 

 might be obtained by burning a mixture of air and coal-gas, 

 in place of hydrogen, in a suitable arrangement of jets. The 

 form of lamp which, after a few trials, I found best adapted 

 for this purpose, consists of two circles of jets, one vertical 

 and the other horizontal, the latter being raised nearly two 

 inches higher than the former. The vertical circle consists 

 of a metal ring, about an inch in diameter, pierced on its 

 upper side by six small holes or jets ; the horizontal circle 

 consists of a hollow metal ring, having an internal diameter 

 of rather more than three inches, with twelve holes drilled 

 on its inner side, so as to form altogether a series of eighteen 

 little jets of flame, six vertical and twelve horizontal, all con- 

 verging to a comiiion centre, which is of course the point pf 



