VOL. LXVI.] PHILOSOPHICAL TRANSACTIONS. 41 



have the figure of the rest of the platina, differing only from them in colour, 

 and in not being so bright, or as it were polished. Others are irregular masses 

 of indeterminate figure, having generally a spongy appearance. The most part 

 of these gold particles were evidently attracted by the magnet, and showed on 

 the surface of the water their 2 distinct poles. These gold particles being put 

 on a piece of charcoal, and the flame of a candle directed on them by the blow- 

 pipe of the chemical pocket laboratory, described by Gustave Von Engestrom, 

 published in the English translation of Crownsted's Mineralogie, ran easily into 

 round balls, which have all the appearance and quality of real gold, except their 

 being in general magnetical or having 2 distinct poles. I make no doubt but 

 this magnetical quality is owing to some platina mixed with the gold. 



Dr. I. could never melt a single particle of true shining platina by blowing 

 strongly on it with the blow pipe ; the only change they underwent by this 

 operation, was to lose their brightness and the greatest part of their magnetical 

 virtue. Having filled a small glass tube with that platina, each end of it 

 attracted both poles of a compass indiscriminately ; but being put to a set of 

 magnetical bars, it became a real magnet, having 2 distinct poles, which he 

 could change at pleasure. He filled another small tube with platina, the hollow 

 of the tube being only of such a size, as to allow the particles of platina to go 

 in freely. He stuck a pin in each end, and fixed the pins with sealing-wax. 

 He directed 5 or 6 electrical explosions from 3 very large jars through the tube ; 

 after which the platina had acquired no polarity. By looking with a microscope 

 at the outside of the tube, the platina was much changed, so as to appear one 

 uninterrupted cylinder of metal, all the interstices between each particle being 

 quite, in appearance at least, obliterated and filled with bright metal. The 

 places which were not bright, were become of a black hue, and appeared to be 

 parts of the platina not melted ; which he found afterwards to be the case. He 

 attempted to shake the particles out of the tube, but he could not succeed. He 

 could only force out some few at the opening with a pin. He separated a little 

 bit of the tube with a file, to push out the cylinder of platina ; but could not 

 succeed without employing a great force : he therefore beat some part of the 

 tube to pieces with a hammer, and found each particle had undergone a remark- 

 able alteration. All of them appeared in several places to have been melted, 

 Gud some little ones seemed to have been entirely in a fluid state ; they all 

 adhered in lumps together so strongly, that many of them could absolutely 

 not be rubbed asunder between the fingers. The inside of the tube exhibited 

 marks of having received impressions of the melted metal. By comparing the 

 separated particles of this platina with particles not exposed to an electrical 

 explosion, they were scarcely to be known for the same substance. He had put 

 some iron filings in a tube of the same size, and directed the same explosion 



VOL. XIV. G 



