on the Nature of certain Bodies, m 



lion in the tube containing the plumbago, but it seemed 

 gradually to combine with the potassium. The two results 

 were exposed to the action of water; the result from the 

 plumbago acted upon that fluid with as much enero-y a-s 

 the other result, and the two volumes of elastic fluids 

 were 1-8 cubical inches and \-g cubical inches ; and both 

 gave the same diminution by detonation with oxycren, as 

 pure hydrogen. Two grains of potassium, by acting upon 

 water, would have produced two cubical inches and one- 

 eighth of hydrogen gas; the deficiency in the result, in 

 which poiassiuu) alone was used, must be ascribed to the 

 Joss of a small quantity of metal, which must have been 

 carried off in solution in the hydrogen, and perhaps, like- 

 wise, to the action of the minute quantity of metallie oxides 

 in the plate glass. The diflference in the quantity of hydro- 

 gen given oft" in the two results, is however too siiirht to 

 ascribe it to the existence of oxygen in the plumbatro. 



1 repeate'd this experiment several times with like results 

 and intvvoor three instances examined the compound form- 

 ed. ]t was infusible at a red heat, had the lustre of plum- 

 bago. It inflamed spontaneously, when exposed to air, 

 generated potash, and left a black powdery residuum. It 

 eflervesced most violently in water, and produced a gas, 

 which burnt like pure hvdrogen. 



When small pieces of charcoal from the willow, that had 

 been intensely ignited, were acted upon by Voltaic electri- 

 city in a Torricellian vacuum, every precaution bcino- taken 

 to exclude moisture from the mercury and the charcoal the 

 results were very difl'erent from those occurring in the case 

 of pkimbago. 



When plumbago was used, after the first spark, which 

 generally passed through a distance of about one -eighth of 

 an inch, there was no continuation of light," without^a con- 

 tact or an approach to the same distance; but from the 

 charcoal a ilame seemed to issue of a most brilliant purple, 

 and formed, as it were, a conducting chain of lio-ht of 

 nearly an inch in length, at the sarne time that elastic mat- 

 ter was rapidly formed, some of which was permanent. 

 After many unsuccessful trials, I at length succeeded in 

 collecting the quantity of elastic fluid given out by half a 

 grain of charcoal ; the process had been conlinutd nearly 

 half an hour. 'Ihe quantity of gas amoimted to nearly aii 

 tighth of a cubical inch ; it was inflammable by the electric 

 ipark with oxygen gas, and four measures of it absorbed 

 tlirte measures of oxygen, and produced one measure and a 

 half of carbonic acid. ' 'Jhc charcoal in this experiment ha^l 



become 



