one of the Trivalcnl Group of Elements. 311 



chemists have only been justified in assuming the former alternative 

 to be the correct explanation. 



The speaker stated that, in order to endeavour to clear up this 

 question, he had most carefully repeated Berzelius's experiments, and 

 that he had confirmed them in every particular ; but having pursued 

 the subject further than Berzelius, he had at last come to conclusions 

 concerning the constitution of the vanadium compounds totally dif- 

 ferent from those drawn by the Swedish chemist, and had succeeded 

 in obtaining the key to the enigma presented by the above anoma- 

 lous crystallographic relations. 



The speaker has proved that the substance supposed by Berzelius 

 to be vanadium, V=68'5, is not the metal, but an oxide, and that 

 the true atomic weight of the metal is 68*5 — 16 = 52'5 (or rather, 

 according to the speaker's exact determinations of the atomic weight, 

 67-3 — 16 = 51-3)*. The highest oxide, the vanadic acid, V O 3 , of 

 Berzelius, hence becomes a pentoxide, V 2 O 5 , corresponding to P 2 O 5 

 and As 2 0°, and the isomorphism of vanadinite with the pyromor- 

 phite group of minerals is fully explained. The suboxide of Berze- 

 lius is a tricxide, V 2 O 3 , whilst the terchloride (V CI 3 ) of Berzelius is 

 an oxychloride, having the formula V O CI 3 , and corresponding to 

 oxychloride of phosphorus, P O CI 3 . The oxide supposed by Berze- 

 lius to be the metal contains 51*3 parts by weight of vanadium to 

 1 6 parts by weight of oxygen ; arid the vanadic oxide of Berzelius 

 also exists, containing 51*3 parts of the metal to 32 parts of oxygen ; 

 to these oxides the empirical formulas V 2 O 2 and V 2 O 4 may be given. 

 Thus we have the following as representing the true composition of 

 these vanadium compounds : — 



Dioxide. Trioxide. Tetroxide. Pentoxide. Oxytrichloride. 

 V=51-3 V 2 2 V 2 3 V 2 4 V 2 5 V0C1 3 



Each of the four oxides can be obtained in the anhydrous state ; 

 the dioxide is prepared as a grey metallic powder by passing the va- 

 pour of the oxytrichloride mixed with hydrogen over red-hot carbon. 

 The trioxide is obtained by the reduction of vanadic acid in a cur- 

 rent of hydrogen ; and the tetroxide is formed by the slow oxidation 

 of the trioxide. 



The lowest, or dioxide of vanadium (V 2 O 2 ), is obtained in solution 

 by the reducing action of nascent hydrogen evolved from zinc, cad- 

 mium, or sodium-amalgam upon the sulphuric acid solution of va- 

 nadic acid, which, passing through all stages of blue and green 



* In his paper on Vanadium, read before the Royal Society (Dec. 19, 

 1867), the author ventured to predict that the difference between the num- 

 ber he obtained (67'3) and that found by Berzelius (6S'5) was probably 

 owing to the fact that the vanadium compounds employed by Berzelius 

 contained traces of phosphorus, which render the perfect reduction of the 

 vanadic acid in hydrogen impossible. Most fortunately this supposition 

 has been singularly verified, inasmuch as Dr. Frankland has kindly placed 

 in the speaker's hands a small specimen of vanadate of ammonia found in 

 Faraday's collection, and labelled " Sent to me by Berzelius, 1831." On 

 examination, this sample was found to contain considerable quantities of 

 phosphorus, thus confirming the speaker's previously expressed opinion. 



