i 4 2 LIFE AND EXPERIENCES CHAP. 



other metals, notably cobalt, in the Keuper sandstone, 

 each grain of sand being surrounded by a coating of 

 copper carbonate and oxide of cobalt. The process 

 of extraction consists in treating the ore with hydro- 

 chloric acid, the copper being afterwards precipitated 

 by metallic iron or zinc. On my visit the manager 

 showed me a dark blue solution which he believed to be 

 a concentrated solution of a copper salt in a peculiar 

 condition, inasmuch as it was not precipitable by zinc. 

 I at once saw that this could not be copper, but that 

 the blue colour was probably due to the presence of 

 the very rare metal vanadium. I asked him to 

 send me some of the solution to test, and found my 

 suspicions confirmed. I inquired in what portion 

 of the ore or residues he found this substance, and 

 after a while obtained from him several tons of a lime 

 precipitate containing this hitherto rare metal. I then 

 worked it up so as to obtain a considerable quantity of 

 the oxide of vanadium, and proceeded to examine the 

 properties of this substance, repeating in the first 

 place the experiments made by the Swedish chemist 

 Berzelius, who had investigated its properties about 

 the year 1838. In working at this subject I found 

 certain discrepancies between my results and those of 

 the great Swede, and after a very considerable time I 

 came to the conclusion that he had been mistaken in 

 the composition of the oxides, and therefore in the 

 atomic weight of the metal. I remember very well it 

 was in the summer of 1867, when we were staying at 

 Roddam, in Northumberland, and I was making the 

 calculation of my analyses that the true explanation of 

 the difference between Berzelius' results and my own 

 flashed upon me. The investigation, when completed, 

 was published in the Transactions of the Royal 

 Society, and also in Liebig's Annalen and the French 



