mm, the Atomic Volume of Sulphur and Nitrogen. 171 
If with the French chemists we divide the ae alents - ~ 
drogen, chlorine and the metals by 2, and \ @: We. forur 
water, H, O or H, O,, their t combining sialaies Wil bi a same 
as that of oxygen. But if we look at the volume of sulphur, we 
find an exception to this deine the specific gravity of its vapor is 
6654, while that of oxygen gas is 1-1057. Talking the combi- 
ning volume of -oxygen as unity, that of sulphur is }, and while 
the volume of the atom of oxygen (= the atomic weight divided 
by the ore is “a shoe by 7-2354, that of — is found 
to be 2:4045. s fact with a similar one in the history of ni- 
trogen, has ware a an unexplained difficulty-in the way of ad- 
mitting that the combining volumes of all the elements should 
be identical. 
In an attempt towards a system of chemical Rear goa some 
suggestions have arisen which will, I think, enable us t explain 
satisfactorily this apparent anomaly. Rejecting the Bh ideas 
of electro-negative and electro-positive relations, as not only base- 
less but erroneous in their tendency, I consider with MM. Ger- 
-— and Laurent, that each class of compounds is derived from 
mal species or primitive type by successive substitutions. 
This poe I have endeavored to extend both by the formation of 
new classes, and by enlarging our views of substitutions, 
In considering such combinations as SO, and Se O,, which 
contain three equivalents of the elements of ‘the oxygen group, 
it was necessary to admit a normal species which should be.a pe- 
lymere of oxygen, and be represented by O,=(OOO). The re- 
placement of one ps ee of oxygen by one of sulphur, would 
yield sulphurous acid gas (OOS), and a complete metalepsis would 
give rise to (SSS). The first compound is prebably the ozone 
of Schénbein, which the late researches of Marignac and de la 
Rive have shown to be in reality only oxygen in a peculiarly 
modified form, since pure dry oxygen gas, by the action of the 
electrical spark, acquires the peculiar odor and chemical properties 
' which distinguish ozone. 'The most characteristic of these are, 
its peculiar odor and its power of discharging vegetable colors, in 
both of which is seen such a close resemblance to sulphurous 
acid gas, as at once to suggest a similarity. 
If we regard sulphur in the form which is known to us, as 
having the oo, ea (SSS), and. consisting of three equiva- 
lents combined in one, the density of its vapor is no longer an 
anomaly, as the patch vapor is condensed to one-third of its 
normal bulk, and its equivalent number being 16 x3=48, its 
atomic volume is 72135, or the same as that of oxygen* gas. 
The difficulty is completely solved in a manner which is accord- 
ant with well-admitted principles. 
In connection with the similarity between ozone and sulphur 
here advanced, it is vee of notice that the odor of sulphur 
