150 Royal Society : — Dr. T. Andrews on the 



dichloride into the platinum boat in such a way that it shall not 

 for an instant be exposed to moist air. After all precautions are 

 taken, the tube is heated to redness, torrents of hydrochloric acid 

 come off, and the evolution of this gas continues for from 40 to 80 

 hours, according to the quantity of dichloride taken. After the evo- 

 lution of any trace of hydrochloric acid has ceased to be perceptible, 

 the tube is allowed to cool, and the boat is found to contain a light 

 whitish grey-coloured powder, perfectly free from chlorine. 



Metallic vanadium thus prepared examined under the microscope 

 reflects light powerfully, and is seen to consist of a brilliant shining 

 crystalline metallic mass possessing a bright silver-white lustre. Va- 

 nadium does not oxidize or even tarnish in the air at the ordinary 

 temperature ; nor does it absorb oxygen when heated in the air to 

 100°. It does not decompose water even at 100°, and may be 

 moistened with water and dried in vacuo without gaining weight. 

 The metal is not fusible or volatile at a bright red heat in hydrogen ; 

 the powdered metal thrown into a flame burns with the most bril- 

 liant scintillations. Heated quickly in oxygen it burns vividly, form- 

 ing the pentoxide ; but slowly ignited in air it first glows to form a 

 brown oxide (possibly V 2 0), and then again absorbs oxygen and 

 glows, with formation of the black trioxide and blue tetroxide, till 

 it at last attains its maximum degree of oxidation. The specific 

 gravity of metallic vanadium at 15° is 5*5. It is not soluble in 

 either hot or cold hydrochloric acid ; strong sulphuric acid dissolves 

 it on heating, giving a yellow solution ; hydrofluoric acid dissolves 

 it slowly with evolution of hydrogen ; nitric acid of all strengths 

 acts violently on the metal, evolving red nitrous fumes and yielding 

 a blue solution ; fused with sodium hydroxide the metal dissolves 

 with evolution of hydrogen, a vanadate being formed. 



One sample yielded on oxidation a percentage increase of 77*94, 

 whereas that calculated from metal to pentoxide is 77*98. Another 

 preparation gave a percentage increase of 70' 8, showing the presence 

 of a small quantity of oxide. On treatment in a current of chlorine, 

 metallic vanadium burns and forms the reddish black tetrachloride ; 

 heated in a current of pure nitrogen, the mononitride is formed. 



The properties of the compounds of vanadium with silicon and 

 platinum are then described in the memoir. 



"On the Continuity of the Gaseous and Liquid States of Matter. 

 — Bakerian Lecture." By Thomas Andrews, M.D., F.R.S. &c. 



In 1863 the author announced, in a communication which Dr. 

 Miller had the kindness to publish in the third edition of his ' Che- 

 mical Physics,' that on partially liquefying carbonic acid by pressure, 

 and gradually raising at the same time the temperature to about 88® 

 Fahr., the surface of demarcation between the liquid and gas became 

 fainter, lost its curvature, and at last disappeared, the tube being 

 then filled with a fluid which, from its optical and other properties, 

 appeared to be perfectly homogeneous. The present paper contains 

 the results of an investigation of this subject, which has occupied 

 the author for several years. The temperature at which carbonic 



