158 Miscellaneous Intelligence. 



charcoal with the zinc pole*. The spark was vivid, and the globules of 

 melted plumbago could be discerned, even in the midst of the ignition, 

 lorming and formed upon the edges of the focus of heat. There were 

 also bright scintillations from combustion, and just on, beyond the 

 confines of the ignited portion of plumbago, was formed a belt of a 

 reddish brown colour, supposed to be iron, from the combustion of the 

 plumbago in that place. The globules were frequently so abundan tas 

 to look like a string of beads, the largest of the size of the smallest 

 shot, others quite microscopic. No globule appeared on the point 

 of the plumbago which had been in the, focus of heat, but here a 

 hemispherical excavation existed, and the plumbago looked like black 

 scoria. 



On the zinc pole, with prepared charcoal, there were peculiar 

 results; the pole was always elongated towards the copper pole, and 

 the black matter accumulated there presented every appearance of 

 fusion, not into globules but into a fibrous and striated form, like 

 half-flowing slag. " It was evidently transferred in the state of 

 vapour from the plumbago of the other pole, and had been formed by 

 the carbon taken from the hemispherical cavity," and was very 

 different to the melted charcoal obtained when botli poles were ter- 

 minated by that substance. On the end of the prepared charcoal 

 were found numerous globules of perfectly-melted matter, spherical, 

 and of a high vitreous lustre. Those most remote from the focus 

 •were sometimes of a jet black like obsidian, others brown, yellow, 

 and topaz coloured, others greyish white like pearl-stones, with the 

 translucence and lustre of porcelain, and others again were limpid 

 like flint-glass, or like hyalate, or precious opal, but without colour. 

 Few of the globules on the zinc pole were perfectly black, few on 

 the copper pole were otherwise, except in one instance, when very 

 pure plumbago from Borrodae was used, and they were then white 

 and transparent. When the points were held vertically, and the 

 plumbago uppermost, no globules were found on the latter, and they 

 were unusually numerous and almost black on the opposite pole. 

 When the points were changed, plumbago being on the zinc, and 

 charcoal on the copper end, very few globules were formed on the 

 plumbago, and none on the charcoal, the last being rapidly hollowed ; 

 whilst the plumbago was as rapidly elongated by matter accumu- 

 lating at its point, which, by the microscope, appeared to be a con- 

 cretion in the shape of a cauliflower of volatilized and melted charcoal. 



Some of the globules being bedded in a handle of wood, bore 

 strong pressure without breaking, and easily scratched flint, window 

 and hard green glass. They sunk rapidly in strong sulphuric acid, 

 much more so than the melted charcoal, but not much more so than 

 the plumbago, from which they were formed. 



With anew deflagratorgood results were obtained, using plumbago 

 at both poles. The pieces of plumbago were one-fifth of an inch 



* The apparatus is in the condition of a single pair of plates. 



