one of the Trivalent Group of Elements. 309 



The beds in the above series which claim the greatest share of our 

 attention are those at the base of the Keuper series, for in these 

 occur the copper and other minerals. The copper, as both blue and 

 green carbonate, occurs disseminated throughout the sand, the ore 

 coating the outside of the grains of sand and the pebbles of quartz. 

 In addition to copper, bands containing lead, both as carbonate and 

 sulphide (galena), occur, also bands and veins of cobalt-ochre, oxide 

 of manganese, and iron-ochre in workable quantity. The copper is 

 extracted from the ore by solution in hydrochloric acid and precipi- 

 tation as metal by scrap iron. The ordinary copper liquor, as well 

 as the oxide of iron precipitated by lime from the solution of the 

 chloride, does not contain any trace of vanadium ; nor was the speaker 

 able to detect any of this metal in the ore as at present worked. 



Following, in the main, the process of preparation adopted by 

 Sefstrom, the speaker obtained from the above-mentioned lime preci- 

 pitate several pounds of pure ammonium vanadate, from which all 

 the other compounds of vanadium can be prepared. 



What now were the conclusions to which Berzelius arrived from 

 his experiments concerning the constitution of the vanadium com- 

 pounds? He corroborated Sefstrom' s statement, that the most cha- 

 racteristic feature of the substance is the existence of an acid-forming 

 oxide, termed vanadic acid, produced whenever any of the oxides are 

 heated in the air. Berzelius also discovered two other oxides of 

 vanadium (of which he ascertained the composition), and likewise a 

 volatile chloride. To the highest oxide he gave the formula VO 3 , 

 to the second VO 2 , and to the lowest (or suboxide) VO ; whilst the 

 chloride was represented by VC1 3 . The atomic weight of the metal 

 he ascertained to be V= 68*5. Berzelius came to this conclusion 

 from the following experimentally ascertained facts : (1) that on pass- 

 ing hydrogen over heated vanadic acid a constant loss of weight 

 occurred, and the suboxide was formed ; (2) that when dry chlorine 

 was passed over the suboxide thus prepared, the volatile chloride was 

 formed, and a residue of vanadic acid remained which was exactly 

 equal in weight to one-third of the acid originally taken for reduc- 

 tion. Hence, assuming that the lowest oxide contains one atom of 

 oxygen (an assumption borne out by the analysis of the chloride), 

 the acid must contain three atoms of oxygen*; and the following for- 

 mulae represent the composition of these compounds according to 

 Berzelius : — 



VO, VO 2 , VO 3 , VCP. (V = 68-5.) 

 The interest attaching to the conclusions which Berzelius fairly 

 drew from his experiments was much heightened by an observation 

 made by Rammelsberg in 1856, as to the exact crystalline form 

 of the mineral vanadinite, a double salt of lead vanadate and lead 

 chloride. 



So long ago as 1780, Werner had observed the identity of crystal- 



* Berzelius concludes that the acid does not contain two atoms of metal, 

 inasmuch as no alum could be formed with potassium sulphate correspond- 

 ing to those formed by well-known sesquioxides. 



Phil. Mag. S. 4. Vol. 35. No. 237. April 1868. Y 



