1821.J Dr, Clarke upon the Gas Blowpipe^ 41$^ 



Article III, 



Observations upon the Gas Blowpipe, and upon some of the more 

 remarkable Results which have been obtained in using this 

 Instrument during a Course of Five Years, in which it has been 

 constantly employed; being a Continuation of former Remarks 

 upon the same Subject,^ By Edward Daniel Clarke, LLD* 

 Professor of Mineralogy in the University of Cambridge ; 

 Member of the Royal Academy of Sciences at Berhn, &c. &c. 



(To the Editor of the Annals of Philosophy,) 



SIR, Cambridge, May 12, 1821. 



A PERIOD of five years has now elapsed since I first began a 

 course of experiments with the gas blowpipe. In all this time 

 those experiments have been of a public nature. Upwards of 

 100 persons were present, March 15 of the present year, when 

 the metalhc base of barytes was revived and exhibited. It had 

 been cut by a file in three places ; and it presented such a high 

 degree of metalhc lustre that it seemed as if the points of three 

 iron nails had been similarly acted upon by the file. This 

 metalhc body being then left covered only by a glass vessel, 

 speedily became oxided, and fell into a white pulverulent earth 

 of barytes. In this experiment, no oil had been used to mix 

 with the barytic earth for the purpose of making its particles 

 adhere ; it was taken from a glass vessel in a compact state ; as 

 it had been prepared with the utmost care by Messrs. Allen, 

 chemists, of London ; and was exposed, per se, to the flame of 

 the gas blowpipe, supported in a pair of forceps, the points of 

 which were made of state. The reasons which have given rise 

 to the opinion that the metallic substance thus so often exhi- 

 bited, is, in fact, the metal of barytes, are simply its property of 

 rapidly decomposing water and atmospheric air ; added to the 

 perfect metallic lustre which it discloses to the action of a file, 

 or other sharp instrument. In addition to which may also be 

 mentioned the appearance which it exhibits prior to its being 

 cut. It has then a highly metallic surface resembhng the 

 stalactites of the black oxide of matiganese ; but of a jet-black 

 shining colour, with occasional metalline particles, disposed inti 

 dendritic crystallization upon the dark surface. If, herediftet^ 

 chemists should determine that these characters are not of 

 themselves sufficiently decisive as to its metalhc nature, still the 

 name of plutonium, which, in a former communication, I ven- 

 tured to give to this appearance, may be considered as useful 

 for its distinction, because, whatever be its real nature, it is a 



* ^w Annals of Philosophy, x.373, xiv. 143, &c. - • ^^"^ 



2d 2 ^ / 



