480 Intelligence and Miscellaneous Articles. 



which the luminous particles, drawn out into a lengthened form, 

 would in the apparent centre of the tail present their ends only, but 

 on each side of it their full extent, to the observer's eye. At any 

 rate such a conjecture would be fully in accordance with the hypo- 

 thesis of a polar force of repulsive character, of which there seem to 

 be other evident indications.— Proceerfw^s of the Astronoinicd Society, 



No. 10, 1859. 



ON THE PRESENCE OF VANADIUM IN THE CLAY OF GENTILLY. 

 BY P. BEAUVALLET. 



M. H. Sainte- Claire Deville terminates a recent note on the 

 occurrence of vanadium in an iron ore of the South of France, by 

 stating that, from what he has heard, vanadium will be found to be 

 more common than might be expected. This refers to the discovery 

 of this metal by the author in the clay of Gentilly, towards the close 

 of the year 1858. By fusing this clay with carbonate of soda, the 

 author obtained a mass of a bluish-green colour. At first he sup- 

 posed this coloration to be due to manganese, but analysis proved it 

 to be produced by vanadium. 



To extract the vanadium from the clay, he proceeds as follows : — 

 Fragments of baked clay * are boiled with 3 per cent, of carbonate 

 of soda and a sufficient quantity of water. After they have been 

 boiled for a few hours, the liquid is separated by filtration ; it con- 

 tains silica, alumina, and nearly the whole of the vanadic acid. It is 

 supersaturated with sulphuric acid and then with ammonia ; and 

 hydrosulphate of ammonia is afterwards added. After two hours of 

 digestion the liquid is filtered, to separate the i)recipitate of alumina 

 and silica. The filtered liquid, which contains the vanadium in the 

 form of sulphovanadiate of ammonia, is treated with an excess of 

 acetic acid, which throws down the sulphuret of vanadium, espe- 

 cially when the liquid is heated to "boiling. This sulphuret, calcined 

 at a red heat, gives vanadic acid. 



The following process may also be adopted for the separation of 

 the vanadium from the solution of soda. The solution is boiled with 

 an excess of muriate of ammonia until no more ammonia is evolved ; 

 the silica and alumina are separated by filtration ; and a solution of 

 tannin is poured into the filtrate, which causes the formation of a 

 voluminous precipitate of tannate of vanadium of a fine blue-black 

 colour ; this, calcined in contact with the air, leaves a residue of 

 vanadic acid. 



M. Terrell, who has treated difi^erent clays of the environs of Paris 

 by the above method, did not find any vanadium in them, but obtained 

 from them titanic and tantalic acids. 



M. Elie de Beaumont mentions that both the iron ore and the 



. Gentilly clay above referred to belong to the tertiary strata. This 



occurrence of vanadium in recent strata at two points so wide apart 



as Gentilly and les Beaux, is a new fact in geology, and merits 



attention, — Comptes Rendus, August 22, 1859, p. 301. 



* The author uses the flower-pots furnished to the Museum by M. Le- 

 cuyer. The red pots contain more vanadic acid than the yellow ones. 

 After they have been exposed for some time to the action of the water, 

 thfey furnish scarcely aiiy more. 



