: 
60 J. W. Mallet on Osmious Acid. 
oxydation, so far as they exist at all, may perhaps be correctly 
viewed as compounds of the preceding inter se. The stability of 
the oxyd (MO,) in the separate state is remarkable—its formula 
is one of rare occurrence. 
The affinity of all the elements of the group for oxygen is 
considerable; it is so even in the case of osmium and ruthenium, 
usually placed among the noble metals. Dumas (Zraité de Chim. 
app.) states that osmium does not oxydize at common tempera 
tures, nor even at 100° C., but I have obtained conclusive evr 
dence that oxydation may go on slowly even at the ordinary’ 
atmospheric temperature. The paper label and the cork of & 
tube containing pure metallic osmium have in the course of sev- | 
eral years become blackened, precisely as organic matter is by 
the fumes of osmic acid, the black tint on the paper decreasing 
from the mouth of the tube along the outside. A piece of white 
paper in which some black platinum residue had been wrapped, 
was strongly stained in the immediate neighborhood of the pow- 
der in the course of a few weeks. The same effect is distinctly ob- 
servable even upon the paper label placed inside a tube of native 
wridosmine (Siberian) in the usual coarse grains—a specimen which 
has lain among other minerals, and has never been placed near 
any artificial preparations of osmium. Osmium, like arsenic and 
antimony, is clearly capable of slowly taking up oxygen at com: 
mon temperatures. At a red heat, Toasting in a current of alt 
affords, as is known, a good method of obtaining osmic acid from 
the iridosmine of platinum residues—just as by similar roasting 
arsenious acid is prepared from the native arseniurets. 
_, it would be a matter of much interest to compare osmium with 
its supposed homologues under circumstances in which we should 
expect it to play an electro-negative part. Frémy has announced 
his belief in the existence of an osmiuretted hydrogen, but such & 
body has not yet been isolated and described, Compounds of 
the metal with ethyl, methyl, &c., would be well wo 
a body which in some states of combination exhibits such a high 
degree of volatility. 
; e 
thenium could be volatilized, at exceedingly high temperatures — 
without oa 
of “mae lance oan — would be made out, but it appe 
from more recent paper that osmium at least may be fused 
obtained as a perfectly the oun volatility of 
+ perie compact mass, 
the _ being due doubtless to.previous oxydation, the cruct — 
bles used being permeable to air. We have seen, a8 
_ B= : ) ba rg 
canta ten ee _— their oxyds are _ volatile = a | 
ith daca iad 
; rth examt 
nation, and it is not unlikely that such might be prepared from 
vious fusion; if this were confirmed, a strong point : 
a ee a a " 
