134' Professor Sillinian's Experiments with flic Blowpipe 



rived, as the combustion of part of the carbon may have 

 somewhat diminished the proportion of that substance. I find 

 that the fusion of the plumbago by the compound blowpipe 

 is by no means difficult, and the instrument being in good 

 order, good results may be anticipated with certainty. As 

 the press is vvaitmg while I write, it is not in my power to de- 

 termine the nature of all of these various coloured globules, 

 and particularly to ascertain whether the abundant white glo- 

 bules are owing to earths combined with the plumbago, or 

 whether they are a different form of carbon. If the former be 

 true, it proves that no existing analysis of plumbago can be 

 correct, and would still leave the remarkable white fume, so 

 abundantly exhaled between the poles of the deflagrator, and 

 so rapidly transferred from the copjier to the zinc pole, entirely 

 imaccounted for. I would add, that for the mere fusion of 

 plumbago, the blowpipe is much preferable to the deflagrator, 

 but a variety of interesting phaenomena in relation to both 

 plumbago and charcoal are exhibited by the latter and not by 

 the former. 



Postscript, April 18. Fusion of Anthracite. 

 The anthracite of Rhode-Island is thought to be very pure. 

 Dr. William Meade (see Bruce's Journal p. ^G) estimates its 

 proportion of carbon at ninety-four per cent. This anthracite 

 1 have just succeeded in melting by the compound blowpipe. 

 It gives large brilliant black globules, not attractable by the 

 magnet, but in other respects not to be distinguished from the 

 dark globules of melted plumbago. The experiment was 

 entirely successful in every trial, and the great number of the 

 globules and their evident flow from, and connexion with, the 

 entire mass, permitted no doubt as to their being really the 

 melted anthracite. 



The Kilkenny coal gave only white and transparent globules; 

 but it seems rather difficult to impute this to impurities, since this 

 anthracite is stated to contain ninety-seven per cent, of carbon. 



I have exposed a diamond this afternoon to the solar focus 

 in a jar of pure oxygen gas, but observed no signs of fusion ; 

 nor indeed did I expect it, but I wished to compare this old 

 experiment with those related above. 



The diamond is now the only substance which has not been 

 jierfectly melted. 



I inserted a piece of plumbago into a cavity in quick lime, 

 and succeeded in melting it down by the blovy-pipe into two or 

 tiiree large globules, adhering into one mass, and occupying 

 the cavity in the lime : these globules were limpid, and nothing 

 remained of the original ajipeaiance of the plumbago except 

 a fe\\ black points. 



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