- 
172 T. S. Hunt on the Anomalies, §c. 
when warmed or rubbed, which is similar to, and often confound- 
ed with that of sulphurous acid gas, although really distinct, is 
strikingly like the odor produced by the electrical gra in- 
deed this last, which is now known to be due to the formation 
‘their compounds with each other, on the one hand, and those of 
phosphorus and arsenic on the other, we are constrained to admit 
that the effects produced by these bodies on the nerves of smell, 
have an intimate and as yet but imperfectly understood relation 
to their chemical properties. 
s to selenium, Iam not aware that the density of its vapor 
has ever been determined, but from that of the solid it appears 
probable that it as well as tellurium has a triple molecule. ‘The © 
compound described as Se O may belong to a type which is seen 
in anhydrous sulphuric acid (SO, ), in which case its formula will 
be (Se, O,), but from its volatility and pungent odor, it is perhaps 
referable to the previous form, and will em = (Sez 02); hybrid 
combinations* of this sort are not unfreque 
In the other exception referred to, we find ‘that while the den- 
sity of the vapors of arsenic and pho sphorus is such that their 
volume is identical with that of oxygen, nitrogen gas is repre- 
sented by two volumes, taking oxygen as unity; and that conse- 
quently while the calculated atomic volumes of gaseous > phospho 
rus and arsenic are 7-2, that of nitrogen gas is 14-4—; in other 
words, its state of condensation i is only one-half that of the others. 
It has already been suggested that elementary nitrogen is prob- 
ably unknown to us, and that the gas which is left when the ox- 
ygen is removed from the atmosphere, is an amid whose formula 
is (NN), corresponding like all similar combinations to four vol- 
-umes; the Se af nitrogen being taken at 14, while that 
of oxygen s 8. Two equivalents of nitrogen being thus ex- 
panded to font volumes, the density is of course just one-half of 
that which corresponds to the normal one, and multiplying the 
observed density by 2, we find that the real specific gravity of 
gaseous elementary nitrogen should be 1-944; its combining vol- 
ume identical with that of oxygen, and the volume of its atom, 
like that of Meat. apn and arsenic, 7'2. If it existed in the 
: ds, M. Lan rent has designated a elass of sompoenas, whe to the 
wesne ae heoa pr eres no small difficulties. Such a s these, are ma combi- 
ations of the mineral kingdom where three or four ‘ho ila may exist in var ying pr” 
i da 
in these hybrid combinations, “a divisibility of atoms to which he assigns no 
its.”’ (See this Journal, ii ser., iv, 405, v, 405, Gerhardt on the Atomic Volume 
of some Minerals of the Regular System, and Laurent on Silicates cates.) 
& 
