_ 1868] Chemistry. 225 
the true formula of vanadic acid is V, O;(O=16). If this be 
correct, it follows that the vanadates form no exception to the law 
of isomorphism, and vanadium must be classed with phosphorus 
and arsenic. The atomic weight of the metal is necessarily cor- 
rected. Berzelius assigned to it the number 68°5 (O=8); but 
these researches prove that the true atomic weight is 51:21 (O=16). 
For a full account of Dr. Roscoe’s investigations we must refer the 
reader to the ‘ Proceedings of the Royal Society,’ No. 97, and shall 
here give only a short account of the oxygen compounds. The 
most interesting of these is the monoxide (Berzelius’s metal), which 
Dr. Roscoe regards as a basic radical, and appropriately names it 
Vanadyl. It forms with chlorine a trichloride V O Cl;, which Ber- 
zelius considered the terchloride of the metal. The monoxide is 
obtained when the vapour of vanadyl trichloride mixed with hy- 
drogen is passed through a combustion-tube containing red-hot 
carbon. It isa grey powder possessing a metallic lustre. It may 
be prepared in solution by the action of nascent hydrogen on a 
solution of vanadic acid. After passing through all shades of blue 
and green, the solution acquires a permanent lavender tint, and 
then contains vanadium in the state of monoxide. The solution 
absorbs oxygen with great avidity. It bleaches indigo and other 
vegetable colouring matters as rapidly as chlorine, and far more 
powerfully than any other known reducing agent. Vanadium ses- 
quioxide, V, O, (Berzelius’s suboxide), is a black powder obtained 
by reducing vanadic acid in hydrogen at a red heat. This oxide 
has also a strong affinity for oxygen. When warmed in the air it 
glows and is reconverted into vanadic acid. At the ordinary tem- 
perature it absorbs oxygen slowly, and is changed into the dioxide, 
Y O,, forming blue shining crystals. Dr. Roscoe goes on to describe 
the constitution of the vanadates, and the compounds of vanadium 
with chlorine and nitrogen. We have no space for an account of 
these, and need only add, that these researches are in the highest 
degree creditable to their author. 
In a practical point of view, recent researches offer to us but 
little of interest. We notice, however, a note by Mr. R. Warington, 
“On the Detection of Gaseous Impurities in Oil of Vitriol,’* which 
may be useful to our readers. These gaseous impurities are usually 
sulphurous acid and lower oxides of nitrogen. ‘To detect the 
former, the author employs a strip of paper imbued with starch, 
and rendered blue at the time of using by immersion in a weak 
aqueous solution of iodine. In making the experiment, about two 
pounds of oil of vitriol are placed in a bottle, which it about half 
fills, and the bottle is violently shaken. The gases in the liquid 
are thus washed out by the atmospheric air, and if sulphurous acid 
* “Chemical News,’ vol. xvii., p. 75. 
