1835.] and Analysis of the Vanadiate of Lead. 39 



the pulverised mineral in dilute nitric acid ; to precipitate 

 the chlorine by nitrate of silver ; to throw down the excess 

 of silver by muriatic acid ; to replace the volatilized nitric 

 and muriatic acids by sulphuric acid ; evaporate to dryness, 

 and fuse the residue with sulphate of potash, in order to 

 separate the lead, and to estimate the quantity of acid by 

 the loss. The results of the analysis were, 



Chloride oflead^Iorine «J \ 993 



Oxide of lead .... 67-99 

 Vanadic acid . . . .21*34 

 Impurity . . . . . *73 



100-00 

 With some corrections, the analyst considers this equiva- 

 lent to, 



Chloride of lead . . . 25-33 



Vanadiate of lead . . .74-00 

 Impurity . . . . .0*67 



100-00 

 No phosphoric acid was detected in it, and a mere trace of 

 arsenic acid was present. 



2. Vanadiate of lead from Wanlockhead according to 

 Mr. Johnston, is found in two states. 1. In the form of 

 mamillee, from the most minute size to that of a pin-head, 

 sprinkled over a surface of calamine. The specific gravity 

 6*99 to 7*23. Opaque; varying in colour from straw-yellow 

 to a reddish-brown ; lustre resinous ; streak white. In the 

 finer specimens, the mineral appears in groups of six sided 

 prisms. 2. In the second state in which it occurs, it re- 

 sembles peroxide of manganese when earthy and porous, 

 presenting an amorphous and rounded appearance ; colour, 

 steel-grey, fusing before the blow-pipe like the first variety, 

 and retaining its yellow colour on cooling. The mineral 

 was found in an abandoned lead mine, but only in one spot, 

 about six fathoms in length, where the vein presented the 

 appearance of having been disturbed by violent causes. 



3. Hausmann noticed a mineral associated with red lead 

 ore, which he suspected to be chromate of lead. It pos- 

 sessed a dark yellowish, or liver brown colour, occurring in 

 small botryoidal and stalactitic forms, glistening feebly in- 



