1SI3.] Method of procuring a very intense Heat. 90 



Article IV. 



On an easy Method of procuring a very intense Heat. By A. 

 Marcet, M.D. F.R. S. Physician to Guy's Hospital. 



(To Dr. Thomson.) 



DEAR SIR, Russel-sqnare, July 8, 1813. 



Amongst the various improvements which have assisted the 

 progress of natural science within the last twenty years, that of 

 carrying on experimental researches upon very small quantities of 

 matter, ought, perhaps, to occupy the first place. The advan- 

 tages which often result from a minute scale of operations are too 

 obvious to require any comment ; and indeed the philosophical 

 records of this country have, of late years, afforded innumerable 

 instances of the utility of this mode of investigation. 



You may, perhaps, think it worth while to point out to the 

 readers of your valuable Journal an easy and convenient method, 

 which occurred to me about a year ago, for producing, upon a 

 small scale, a degree of heat which has, I believe, never been 

 exceeded in intensity, unless it be by the magnificent voltaic 

 battery lately exhibited by Mr. Children. The process in question 

 simply consists in urging the flame of a lamp of spirit of wine 

 by a current of oxygen gas. The apparatus most convenient for 

 this purpose is a tin vessel, or gas holder, such as represented 

 in Plate IX. fig. 2, from which a small jet of oxygen gas is 

 forced out, with some degree of violence, by the introduction 

 of water, through a funnel of one or two feet in length. If a 

 diamond be exposed to the flame of a lamp, thus acted upon by 

 the jet of gas, it burns, and disappears in a few minutes. 

 Plat ina wire of moderate thickness is instantly melted, and 

 globules of ttiis metal, weighing as much as 4 or 5 grains, can 

 thus be obtained in quick succession.* During this process of 

 fusion, a scintillation of the metal is observed, as if it was 

 undergoing combustion; but this appears to be owing to minute 

 particles of melted platina, which are simply dispersed by the 

 intensity of the heat. Iron wire is burnt by this means with a 

 degree of rapidity and brilliancy which even exceeds that of 

 Ingcnhouz's striking mode of burning iron wire in oxygen gas ; 

 and small needles of quartz are readily melted and vitrified by 

 the same means. 



I am not aware of this mode of excitement having heen 

 employed before. Intense degrees of heat had long been pio- 



' II was from globules uhlainrd l)y this process iliat Dr. Wollii-lon >uc- 

 • ceded in drawing platina wire of extreme minuicnrs-, as stated in the papei 

 which be hsi latch given to the Royal lociety on the subject, 



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