1876.] 



two new Vanadium Minerals. 



Ill 



The vanadate of aluminiuni and the ferric oxide precipitated together 

 by acetate of ammonium are separated by fusion with sodium carbonate 

 and subsequent boiling with water. The vanadic acid in the acidified 

 solution is then reduced by sulphur dioxide, the liquid well boiled, and 

 the vanadium estimated volumetrically by means of potassium per- 

 manganate. The larger portion of the vanadium remains in solution 

 after the addition of ammonium acetate, and this is precipitated as lead 

 metavanadate by the addition of lead acetate solution. The lead salt is 

 dissolved in nitric acid, and the lead thrown down by sulphuretted 

 hydrogen, the filtrate on evaporation yielding pure vanadium pentoxide, 

 which after ignition is weighed. This method was likewise made use of 

 for the separation of vanadium in the portion of mineral which served 

 for the estimation of the alkalies. 



A direct assay of the vanadium was made by heating 0*5105 grm. of 

 the mineral with strong sulphuric acid, diluting with water, reducing 

 with a current of sulphur dioxide, and titrating with a standard solution of 

 permanganate of 1 cub. centim. = 0-00534 grm, of metallic iron. Of this 

 solution 17-3 cub. centims. were needed ; this corresponds to 29-5 per cent, 

 of vanadium pentoxide, the change of oxidation being from Yfi^ to Y^O.. 

 From this must, however, be deducted the amount of vanadium pentoxide 

 equivalent to 1*13 per cent, of ferric oxide ; this leaves 28*21 per cent, of 

 YgOg, an amount closely approximating to that (28*6) obtained by analysis. 



Dr. James Blake, in his communication referred to above, states : — 

 " At the suggestion of my friend Professor Gribbs, I propose to name 

 the mineral Roscoelite, should the name not be already appropriated." 



No. 2, — The second vanadium mineral, to which I propose to give the 

 name of Mottramite, occurs as a crystalline incrustation on Keuper 

 sandstone found at Alderley Edge and at Mottram St. Andrew's, in 

 Cheshire, and at other localities. 



The incrustation is usually very thin ; but occasionally it becomes 3 or 

 4 millimetres in thickness, and in one or two cases masses almost the 

 size of a walnut have been found. Sometimes the incrustation has a 

 black velvety appearance, and consists of numerous extremely small 

 crystals, so minute that their form has not yet been ascertained. More 

 commonly, however, the mineral possesses a compact character. The 

 crystals are black by retiected light, but very thin particles are sub- 

 translucent and transmit yellow light. The compact mineral is purplish 

 brown and opaque. The lustre of the crystals is resinous. Streak yel- 

 low. Hardness of compact portion about that of calc-spar. Specific 

 gravity 5*894. 



Behaviour before the hlowpiije. — In the closed tube a little water is evolved 

 on heating, and the mineral fuses very easily. On asbestos it fuses 

 easily and slightly tinges the flame green. Heated on charcoal with 

 sodium carbonate in reducing flame, a yellow incrustation and grey 

 malleable bead are obtained. On dissolving the bead in nitric acid and 



