67 



self authorized to assert, without hesitation, that radiant light con- 

 sists in undulations of the luminiferous aether. The general infer- 

 ences he draws from his arguments are, that it is clearly granted by 

 Newton that there are undulations, although he denies that they 

 constitute light ; and that it being shown in the three first corolla- 

 ries of the Eighth Proposition, that all cases of the increase or dimi- 

 nution of light are clearly referable to an increase or diminution of 

 such undulations, and that all the affections to which the undulations 

 would be liable are distinctly visible in the phenomena of light, it 

 may~therefore be very logically inferred that the undulations are 

 light. 



Dr. Young proceeds to attempt the removal of some apparent dif- 

 ficulties in the system which he has adopted ; and concludes with a 

 summary comparison of light with heat, which he supposes to differ 

 from it only in the magnitude and frequency of its undulations or 

 vibrations. 



An Analysis of a mineral Substance from North America, containing 

 a Metal hitherto unknown. By Charles Hatchett, Esq. F.R.S. 

 Read November 26, 1801. [Phil. Trans. 1802, p. 49.] 



This substance, which was lately found among the minerals in the 

 British Museum, appears by an entry in Sir Hans Sloane's Cata- 

 logue, to have been sent to him with various specimens of iron ores, 

 by Mr. Winthrop of Massachusetts, whence it is conjectured that it 

 is the produce of that province. Its resemblance to the Siberian 

 chromate of iron first attracted Mr. Hatchett's notice. It is of a 

 dark brownish gray ; its longitudinal fracture is imperfectly lamel- 

 lated, and the cross fracture shows a fine grain. Its lustre is vitre- 

 ous ; it is moderately hard, and very brittle. 



The analysis was conducted with all the chemical agents usually 

 applied upon those occasions ; and the whole process is minutely de- 

 scribed in the paper. From these experiments we learn that this ore 

 consists of about one quarter of iron, and three quarters of a sub- 

 stance hitherto unknown, but now proved to be of a metallic nature, 

 both by the coloured precipitate which it forms with prussiate of 

 potash and with tincture of galls, and by the colour which it com- 

 municates to phosphate of ammonia, or rather to concrete phosphoric 

 acid when melted with it. 



From the experiments made with the blowpipe, it seems to be 

 one of those metallic substances which retain oxygen with great ob- 

 stinacy, and are therefore of difficult solution. That it is an acidi- 

 fiable metal appears from the circumstance of the oxide turning litmus 

 paper red, expelling carbonic acid, and forming combinations with 

 the fixed alkalies ; but in many points which are enumerated, it is 

 manifestly very different from the acidifiable metals hitherto known, 

 such as arsenic, tungsten, molybdena, and chromium, and it appears 

 to differ still more from the lately discovered metals known by the 

 names of uranium, titanium, and tsjlurium. 



