a new mineral species. 16"? 



as an arseniate of lead, to some varieties of which mineral it 

 has a strong resemblance. On analysis, however, it proved 

 different ; and though I failed in obtaining pure oxide of chro- 

 mium, yet I suspected at first that it contained a considerable 

 quantity of chromic acid. Repeated attempt^, however, to ob- 

 tain a. pure oxide having failed, and many properties manifest- 

 ing themselves which chromium does not exhibit, I came at 

 length to the conclusion that it contained a new metallic sub- 

 stance- This substance I was engaged in examining when the 

 letter of Berzelius in the Annates de Chimie, came to hand, 

 and showed me that my new metal was the Vanadium of Sef- 

 strom- My stock of the mineral was very small, and it was 

 from a portion of it, weighing only seven grains, that I pre- 

 pared the compounds of Vanadium which I soon after exhibited 

 to the Royal Society of Edinburgh. 



It is a matter of regret that both the prior discoverers should 

 have distinguished this metal by names so unwieldy. That 

 of Sefstrom, though less classical, is the more manageable of 

 the two, yet it is time that the northern fashion of naming 

 metals after the barbarous deities of their forefathers should 

 be exploded. 



The Vanadiate of lead, or minerals containing the metal in 

 combination with lead, I have met with in two forms differing 

 very much from each other. 



I. — The more common has much resemblance externally 

 to some arseniates — approaches also in colour to that of some 

 phosphates, and molybdates of lead. It is opaque, varying in 

 colour from a straw yellow to a reddish-brown, and is gene- 

 rally dull, though in one beautiful wax-yellow specimen it has 

 very considerable lustre- The lustre of fractured surfaces is 

 resinous. It is scratched by the knife, giving a white streak ; 

 is brittle, and has a conchoidal fracture. The specific gravity 

 in two specimens was 6-99, and 7-23 respectively. 



It occurs most abundantly in small mamilla*, from a minute 

 microscopic size to that of a large pin head, sprinkled over a 

 surface of calamine. Occasionally it forms a thin coaling upon 

 the calamine. In the finer specimens the individuals are 'larger, 

 and exhibit groups of six-sided prisms, disposed sometimes in 

 ;i dendritical form, but more commonly in rounded pisiform 



