Royal Institution. 307 



corresponding to the following resistances, 



small shot R=^ 4 ' 4 , 



large shot R=i? 6 . 

 Whether in reality the index does increase with the diameter of the 

 shot must be left to be determined by more extended experiments ; 

 meantime it may be assumed that the general formula in this paper 

 represents with tolerable accuracy the law of resistance and the loss 

 of velocity ofj)rojectiles varying from 8 - 8 lbs. to 251 lbs. in weight, 

 from 3 inches to 9 inches in diameter, and from 1500 to 600 feet per 

 second in velocity. 



ROYAL INSTITUTION OF GREAT BRITAIN. 



February 14, 1868. — " On Vanadium, one of the Trivalent Group 

 of Elements." By Henry E. Roscoe, B.A., F.R.S. 



The metal vanadium (so called from Vanadis, a cognomen of the 

 Scandinavian goddess Freia) was discovered in 1830 by Sefstrom in 

 the celebrated Swedish bar-iron made from the Taberg ore. From 

 this source, even when using many pounds of the iron, Sefstrom 

 obtained only minute quantities of the new substance ; but he found 

 it in somewhat larger amount in the slag or cinder produced in the 

 reduction of the iron ore. Sefstrom ascertained some of the most 

 peculiar characters of the substance, proved it to be a new element, 

 and prepared some of its compounds in the pure state. The reac- 

 tions by which vanadium can be separated and distinguished from 

 all the other elements are :• — (1) The formation of a soluble sodium 

 vanadate when the vanadium compounds are fused with sodium car- 

 bonate ; (2) the formation of an insoluble ammonium vanadate when 

 sal-ammoniac is added to the solution of a soluble vanadate ; (3) the 

 production of a splendid blue solution when this ammonium-salt, 

 dissolved in hydrochloric acid, is warmed with reducing agents such 

 as oxalic acid. 



Sefstrom, not having leisure to prosecute the full examination of 

 the properties of the new metal, handed over his preparations to 

 Berzelius ; and it is to the investigations of the great Swede (1831) 

 that we owe almost all our acquaintance with the chemistry of va- 

 nadium. 



Since Berzelius's time vanadium has been discovered in many 

 minerals, of which a lead ore containing lead vanadate and called by 

 the mineralogists vanadinite, is the most important. It has also been 

 found in many iron ores, in clay, bricks, and even in caustic soda. 

 Still the quantity of the substance found in all these various sources 

 has been extremely small — so much so, that the vanadium compounds 

 must be reckoned amongst the greatest of chemical rarities, and we 

 find them quoted in the price-lists of dealers in chemicals at Is. 6d. 

 per grain, or £35 per ounce ! It is clear that our knowledge of the 

 chemical properties of a substance so rare must necessarily be but 

 incomplete, as the difficulties of obtaining exact or satisfactory re- 

 sults with small quantities of material are evident ; and, in fact, the 

 statements of the only persons who have worked upon the subject 

 recently (Schafarik, Czudnowicz), instead of giving us any more 



