1885.] Obo [Genth and Vom Rath, 



vanadic and phosphoric acids. As this separation is not complete, the 

 precipitate was fused with sodium carbonate and lixiviated with water, after 

 having reduced the manganic acid by a few drops of alcohol. Iron was 

 separated from zinc and manganese by sodium acetate, the zinc precipitated 

 by hydrogen sulphide from the cold filtrate, after acidulating strongly with 

 acetic acid, and finally the manganese by sodium carbonate. In the 

 united solutions, containing vanadic and phosphoric acids the sodium car- 

 bonate was nearly neutralized with acetic acid, and the two acids precipi- 

 tated either by mercurous nitrate or lead acetate. In the first case the 

 mercury was driven otf at the lowest possible temperature, then a little 

 nitric acid was added, the liquid evaporated to dryness, after which the 

 residue, containing pentoxide of vanadium and metaphosphoric acid, was 

 ignited ; in the second place, the lead salt was mixed with a little nitric 

 acid, the lead removed as sulphide, the filtrate evaporated and the residue 

 ignited. 



It now remained to separate the phosphoric acid from the vanadic pent- 

 oxide. They were dissolved in boiling hydrogen chloride, completely re- 

 duced by sulphurous acid, and after having added a little tartaric acid and 

 a large excess of ammonia, precipitated with magnesia solution. On account 

 of the minute quantity of phosphoric acid, the liquid was allowed to stand a 

 long time in order to secure a complete precipitation, but, in doing this, a 

 small quantity of the reduced vanadic acid was re-oxydized and contami- 

 nated the phosphate with a minute quantity of magnesium-ammonium 

 vanadate. It was necessary, therefore, to re-dissolve in hydrogen chloride, 

 and after addition of a little sulphurous and tartaric acids, to re-precipitate 

 by ammonia, when a perfectly white pyrophosphate of magnesium was 

 obtained. 



Vanadinite, 



Prof. Silliman was the first to observe vanadinite in pale, yellow hex- 

 agonal crystals at the Lake Valley Mii^es. 



a. At the Sierra Bella it is found on wad in thin coatings, consisting ot 

 minute crystals of a brownish yellow color which, under the microscope, 

 show bright hexagonal prisms with the basal plane and the pyramid 

 slightly indicated ; powder yellow. Analysis a. 



b. At the Sierra Grande several varieties are found. 



1. Beautiful crystals, the largest not over 5""" long and 2.5 to 3™™ thick ; 

 hexagonal prisms, terminated by the basal plane and the pyramid. The 

 angle between the prism and pyramid was found by measurement to 

 be nearly 130°. Tlie planes are often rough, as if corroded by a solvent, 

 and the crystals frequently show cavities, some appear as skeleton-like 

 residues. Smaller crystals ot about 1.5 to 3°'"' in length are perfectly de- 

 veloped and show smooth brilliant faces. The color is orange-yellow, 

 varying from wax-yellow on one side to a deep orange-red, the termina- 

 tions being generally of the darkest color ; cloudy. Powder pale orange- 

 yellow. Lustre greas3% inclining to vitreous. Associated with pyrolusite 



