482 M. Th. Sheerer on two Norwegian 



t>' 



on the identity of electricity from different sources, and with 

 those of Fusinieri on the statical electrical discharge, it would 

 follow as a corollary that every disturbance of electrical equi- 

 librium is inseparably connected with an equivalent disturb- 

 ance of the molecules of matter. In the remarks of Professor 

 Schcenbein to which I have alluded, he says that my experi- 

 ments seem to prove the transmission of the current from one 

 electrode to the other to be effected only by chemical action. In 

 Exp. 5, I employed the diminution of oxygen as a measure 

 of the quantity detached, conceiving that at the intense heat 

 which is produced not a particle of zinc would escape oxidation, 

 and without concluding that chemical action was absolutely es- 

 sential to the existence of the voltaic arc. I must at the same 

 time state that the passage of the current is, as proved in these 

 experiments, materially modified by the nature of the elastic 

 medium through which it passes, and is greatly aided when 

 such medium is capable of uniting chemically with the elec- 

 trodes. In pure dry hydrogen, I have never yet been able to 

 maintain a continuous arc, except with charcoal, which forms 

 carburetted hydrogen ; and Davy in reference to his experi- 

 ment of burning charcoal i7i vacuo states, that a gas was formed 

 which detonated with oxygen ; the probability is that some 

 slight portion of air obtained access, and thus carbonic oxide 

 was formed. On the peculiar relation between the electrodes 

 and the elastic intermedium, I feel at present unable to give a 

 clear opinion ; the subject is peculiarly difficult; I will content 

 myself with stating my present notion to be, that the voltaic 

 arc bears a similar relation to common flame, to that which 

 electrolysis bears to ordinary chemical action. 

 4, Hare Court, Temple, May 7, 1840. 



LXXIII. On two Norwegiaji Cobalt Ores from the SJcutteru- 

 der Mine. By Th. Scheerer.* 



TN the cobalt mines of Modum in Norway (near Christiania) 

 -■■ are found, besides the common cobalt glance, two other 

 distinct cobalt minerals, which differ in their external cha- 

 racters from the usual ore. The following are the descrip- 

 tions of these minerals : — 



First kind. It occurs massive as well as crystallized, has 

 the lustre of arsenical iron, and exactly the same crystalline 

 form, even the characteristic brachydiagonal striae. In 

 hardness likewise, and also its spec. grav. = Q''2'i.t it does Txoi. 

 differ much from that mineral. It is shown by the blowpipe, 



* An extracr, oommnni^nteci b.v tbp Anti^o-j fiom the original article 

 published 'n Poggendorff's Annalen^ vol. xlii. p. 546. 



