J. W. Mallet on Osmions Acid. 55 
by Sénarmont: This was found to be homceomorphous with 
stannic and (the rutile form of) titanic acid. The bi-chlorid of 
tin and potassium too is reported as crystallizing in regular octa- 
hedrons, like the corresponding salts of iridium, platinum, and 
palladium. 
The arsenic section, as given by Dana, includes nitrogen, 
eertores, arsenic, antimony, bismuth, osmium, and tellurium. 
he last-named is marked as doubtful, and should decidedly be 
ar with sulphur and selenium, to which it is analogous in 
y far the greater number of its compounds. 
In one of the interesting memoirs lately published by Dumas 
on the numerical relations subsisting among the atomic weights 
of the elements, the arsenic series is thus given: 
Atomic weights. 
Nitrogen, sai es oe 
Phosphorus,- - - . - .144+17=81 
Arsenic, - - - - 14+17+44=75 
Antimony, - -— - - 144+17+88=119 
Bismuth,- ~- - - 144+17+176=207 
and the parallelism of this series with that of chlorine, iodine, 
&c., is supposed to be shown in the following lines 
F (19) Cl (35°) Br (80) I (127) 
members in each of the vertical columns (a difference not strictly 
ght out in the ease of phosphorus and chlorine), and in 
whic antimony is given a higher atomic weight than in the 
Preceding table. Osmium is not included, but in a supplemental 
note since published we find it placed, with an equivalent some- 
what higher than that usually adopted, in the sulphur group, 
*etving to complete the following two lines of equivalents: 
Mg (1225) On (20) Sr (48°75) Ba (685) Pb (1035) 
0(8) S (16) Se 139-76) Te (645) Os (99°) 
between the paired members of which a common difference of 4 
8 Supposed to exist. ss ogi : | 
Let osmium and ruthenium be brought into the arsenic group, 
and the series of atomic weights will then stand thus: 
Atomic weights. 
itro ss . : 
Phosphorus,- - - - 14+17=81 
thenium, - - - 14417+22=53 
Wien. +  44-174+44=75 
Osmium, - - - + 14+17+66=97 
Antimony, - - - + 14+17+88=119 
Bpinush, = 9: 2. 44417+176=20% 
