mi, i .1 -:1m and.] CABNOTITE AND ASSOCIATED MINERALS. 19 
hydrochloric-acid gas, as recommended by Smith and Hibbs a for the 
expulsion of vanadium from alkaline vanadates. The removal of 
vanadium being incomplete, the contents of the boat were again 
evaporated with nitric acid and again distilled, and these operations 
were repated till no further evidence of a brown distilate appeared. 
The boat now contained only magnesium and alkalies with a little 
calcium. The distillates, containing all the vanadium that was in the 
boat, had been collected in U -tubes charged with water, and were 
eventually obtained in sulphuric solution for further treatment by 
evaporating with sulphuric acid in porcelain. 
The precipitate of A1 2 3 , etc., was dissolved in nitric acid, evap- 
orated almost to dryness in platinum, and boiled with sodium-hydrox- 
ide solution. These operations were repeated on the precipitate after 
filtration. The iron and titanium thus purified were redissolved, pre- 
cipitated by ammonia, weighed, redissolved by acid potassium sulphate, 
and the ferric iron was reduced by h} 7 drogen sulphide and titrated with 
permanganate after boiling out the reducing agent. The titanium 
was then found colorimetrically b} r hydrogen peroxide. 
The combined alkaline filtrates were heated with excess of ammo- 
nium nitrate to separate alumina from most of the vanadium. The 
precipitate was redissolved in nitric acid, reprecipitated by ammonia, 
then ignited and weighed and redissolved by acid potassium sulphate. 
The sulphuric solution was reduced by hydrogen sulphide, boiled and 
filtered from platinum sulphide, again boiled in a current of carbon 
ioxide, and titrated hot with permanganate. Sulphur dioxide gas was 
hen introduced, boiled out in a current of carbon dioxide, and the 
itration repeated, this second result being taken as representing the 
2 4 equivalent to the V 2 5 that still contaminated the A1 2 3 . Deduct- 
ing the V 2 5 thus found from the combined weight of A1 2 3 and V 2 O s 
jave the A1 2 3 of the soluble constituent of the sandstone. 
The combined filtrates from the alumina were evaporated and ignited 
:o remove ammoniacal salts; the residue was converted to sulphates 
md united with the earlier solution of vanadium sulphate. The 
vanadium in it was then determined precisely in the manner already 
lescribed, and when added to that found with the alumina and calcu- 
ated to V 2 3 gave the total in the sandstone. 
A check was made by dissolving the sandstone in hydrofluoric and 
ulphuric acids in a current of carbon dioxide and titrating the V 2 3 
vith permanganate. The figure thus obtained was a trifle below that 
ound as above detailed, and this is to be attributed to the presence of 
, very little vanadium as V 2 O s in carnotite, and probably as a lead 
r anadate. All the uranium and most of the trifling amount of lead 
ould be extracted by cold dilute nitric acid, showing that they were 
oreign to the green substance 1 . 
"Jour. Am. Chem. Soc, vol. l6, 1894, |>. 578. 
