320 



Prof. Roseoe on Vanadium. 



[Apr. 7, 



solution of tetrasodiimt vanadate. If calcium chloride be added to a solu- 

 tion of the trisodium salt, dicalcium vanadate is precipitated, the solution 

 becoming strongly alkaline from formation of calcium hydroxide and 

 absorbing carbonic acid from the air. Complete analysis showed that 

 the calcium salt contains '2j molecules of water of crystallization, whilst 

 the barium salt is anhydrous. 



Lead Vanadates. 



1. Tribasic or Ortho-Lead Vanadate, Pb 3 2(YO,).— Obtained as a light 

 yellow insoluble powder on precipitating the tribasic sodium salt with a 

 soluble lead salt ; it yielded on analysis 11*75 per cent, of vanadium, the 

 calculated quantity being 12*04 per cent. 



2. Vanadinite, the Double Orthoranadate and Chloride of Lead, 

 3Pb, VO,-fPb CI, can be artificially prepared by fusing for a few hours a 

 mixture of vanadic acid, oxide of lead, and chloride of lead, in the above pro- 

 portions, together with an excess of sodium chloride. After cooling, a 

 greyish crystalline mass is left, containing cavities filled with long crystals 

 having the same colour as the mass, "Ahich under the microscope could be 

 distinguished as six-sided prisms. The crystalline powder is then boiled 

 with water until no further traces of soluble chlorides are extracted. 



The following analysis shows that this substance has the same composi- 

 tion as the vanadinites from Zimapan and vVindischkappel, analyzed by 

 Berzelius and Kammelsberg* : — 



Natural ranadinite. 

 Calculated. Zimapan, Windiselikappel, Artificial 

 3 (Pb> Y0 4 ) Pb CV Berzelius. Eannnelsberg. Tacadinite. 



Lead 73-03 70 4 71*20 71*96 



Vanadium.... 10*86 9*77 11*11 



Chlorine .... 2*50 2*54 2*23 2*31 



Oxygen 13*55 



The specific gravity of the artificial vanadinite at 12 = C. is 6*707, that 

 of the natural being 6*SS6. 



3. Basic Di-Lead Vanadate, 2(Pb_ V, O.) + Pb O.— This salt is precipi- 

 tated as a pale yellow powder when acetate of lead is added to a solution 

 of disodium vanadate, the liquid acquiring an acid reaction. It is completely 

 insoluble in water and in dilute acetic acid, but dissolves readily in nitric 



acid. 



Calculated. Mean found. 



Pb. = 1035*0 69*92 70'1S 



Y 4 = 205*2 13*86 13*3 



0 1S = 240-0 16*22 



1480*2 



* Pyromorphite and apatite hare already been artificially prepared by Derille and 

 Caron, and also by Debray. whilst mimetesi&e has been obtained artificially by 

 Lechartier- 



