690 
PROFESSOR ROSCOE’S RESEARCHES ON VANADIUM. 
celain tube (E E') placed in a Hofmann’s furnace and protected in the central portions, 
where it is heated, by an outer casing of sheet iron. The porcelain tube is connected 
with the hydrogen apparatus by means of the wide glass tube (F F') provided with the 
tub ulus (G), and narrowed down to join the drying- tube at F\ The joint between the 
porcelain and glass tubes is made of seamless caoutchouc well wired, and covered by an 
outer short glass cylinder, the space between the tubes and the cylinder being filled 
either with mercury or fused paraffin, and a similar joint is placed at the further end of 
the porcelain tube. 
The introduction of the anhydrous dichloride without exposure to the air is effected 
by means of the tubulus (G), the dichloride being contained in the bent tube (H) in 
which it was prepared and sealed up in hydrogen. After the whole arrangement has 
been set up, the platinum boat being in position as shown in the figure, hydrogen is 
allowed to pass through the apparatus for twelve hours to dry it completely and clear 
out the air ; the caoutchouc stopper of the tubulus is then withdrawn and the end of the 
tube containing the dichloride cut off, and the tube and stopper quickly replaced, so 
that the crystals lie in the horizontal portions of the tube. The bent tube is next so 
turned in the stopper that the crystals of dichloride fall out and are collected in the 
platinum boat placed below. This boat, charged with dichloride, is then drawn into the 
centre of the porcelain tube by means of the platinum wire, the end of which (W) 
passes through a small hole in the caoutchouc tube at the end of the apparatus. As 
soon as the boat is in position, the wire is cut off short at the end of the glass tube, a 
proper joint made, and an exit- tube attached dipping under sulphuric acid. 
Before the porcelain tube is heated, the caoutchouc stopper of the tubulus is sur- 
rounded by a bath of paraffin, and the hydrogen is allowed to bubble through for six 
hours. The temperature of the porcelain tube is then gradually raised to the highest 
point (a bright red heat) which the Hofmann’s furnace will yield, and kept constant 
until the reduction is complete. Torrents of hydrochloric acid gas at once come off, 
and the process must be continued for some hours after the last trace of acid can be de- 
tected in the hydrogen. The process lasts from forty to eighty hours, according as the 
quantity of dichloride employed varies from 1 to 3 or 4 grms. 
Metallic vanadium prepared by reduction from the dichloride in hydrogen is a light 
whitish grey-coloured powder, which under the microscope reflects light most powerfully, 
and appears as a brilliant crystalline metallic mass possessing a silver-white lustre. It 
is remarkable that vanadium thus prepared does not oxidize or even tarnish in the air at 
the ordinary atmospheric temperature, nor does it decompose water at the ordinary tempe- 
rature, and it may be moistened and dried in vacuo frequently without gaining in weight. 
Vanadium is neither volatile nor fusible when heated to redness in hydrogen. When 
the powdered metal is thrown into a flame, or rapidly heated in an excess of oxygen, it 
burns with the most brilliant scintillations, and when slowly heated in a current of air 
it glows brightly with absorption of oxygen, forming in the first place a brown oxide 
(V 2 O or V 2 0 2 ) ; and on further heating this oxide again glows, and passes through the 
