314 Scientific Intelligence, [Oct. 



deflagrated, being completely dissipated in brilliant scintillations; the 

 substance was rapidly consumed and no fusion was obtained. This 

 kind of effect occurred most distinctly when there was a plumbago 



fiece on the copper side, and a piece of charcoal on the zinc side, 

 have already mentioned the curious result which is obtained when 

 this arrangement is reversed, the charcoal on the copper, and the 

 plumbago on the zinc side ; this effect was now particularly distinct 

 and remarkable, the charcoal on the copper side was rapidly volatilized, 

 a deep cavity was formed, and the charcoal taken from it, was instantly 

 accumulated upon the plumbago point, forming a most beautiful 

 protuberance, completely distinguishable from the plumbago, and pre- 

 senting when viewed by the microscope, a congeries of aggregated 

 spheres, with every mark of perfect fusion, and with a perfect metallic 

 lustre. I would again recommend this arrangement when the object 

 is to attain fine pieces of melted charcoal. 



** Jpril H. — In repeating the experiments to-day, I have obtained 

 even finer results than before. The spheres of melted plumbago were 

 in some instances so thickly arranged as to resemble shot lying side by 

 side; in one case they completely covered the plumbago, in the part 

 contiguous to the point on the zinc side, and were without exception 

 white, like minute delicate concretions of mammillary chalcedony ; 

 among a great number there was not one of a dark colour except that 

 when detached by the knife they exhibited slight shades of bro^ n at 

 the place where they were united with the general mass of plumbago. 

 They appeared to me to be formed by the condensation of a white 

 vapour which in all the experiments, where an active power was 

 employed, 1 had observed to be exhaled between the poles and partly 

 to pass from the copper to the zinc pole, and partly to rise vertically in 

 an abundant fume like that of the oxide proceeding from the combus- 

 tion of various metals. I mentioned this circumstance in the report of 

 my first experiments, but did not then make any trial to ascertain the 

 nature of the substance. Although its abundance rendered the idea 

 improbable, 1 thought it possible that it might contain alkali derived 

 from the diarcoal. It is easily condensed by inverting a glass over the 

 fume as it rises, when it soon renders the glass opaque with a white 

 lining. Although there was a distinct and peculiar odour in the fume, 

 I found that the condensed matter was tasteless, and that it did not 

 effervesce with acids, or affect the test colours for alkalies. Besides, as 

 it is produced apparently in greater quantity, when both poles are ter- 

 minated by plumbago, it seems possible that it is white volatilized car- 

 bon, giving origin, by its condensation, in a state of greater or less 

 purity, to the grey, white, and perhaps to the limpid globules. 



** The deflagrator having been refitted only at the moment when a 

 part of this paper had already gone to the press, and the remainder is 

 called for, 1 am precluded by these circumstances from trying the 

 decisive experiment of heating this white matter by means of the solar 

 focus in a jar of pure oxygen gas, to ascertain whether it will produce 

 carbonic acid gas. 



" This trial I have this morning made upon the coloured globules 

 obtained in former experiments ; they were easily detached from the 

 plumbago by the slightest touch from the point of a knife, and when 

 collected in a white porcelain dish, they rolled about like shot, when 

 the vessel was turned one way and another. To detach any portion* 



