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3 . 
J. L. Stockwell on secular variation in the Earth’s Orbit. 87 
bismuth the antimony series differs in that the salts of the for- 
mer metal are decomposed by water, according to Heinz and 
Ruge, into basic salts containing equal equivalents of acid and 
; here, also, no immediate salt is yet known. A more im- 
portant difference lies in the fact that oxyd of bismuth appears 
to form one, if not two, acid sulphates. I have analyses indi- 
cating the existence of compounds of the neutral salt with 
three atoms of hydrate of sulphuric acid; and also of a salt 
erystrallizing in beautiful pearly scales, and containing equal 
equivalents of the neutral sulphates of bismuth and potash. 
A salt with three equivalents of sulphate of potash has been 
described by Heinz. The further account of these bodies must 
be reserved until their analyses have given more trustworthy 
results, 
- Boston, April, 1868. 
Art. XI.—On the Secular Variation of the Elements of the 
Earth's Orbit ; by Joun L. SrockweLy. With a plate. 
these forces depend, must affect the intensity of the forces 
themselves, thus have an important bearing on the devel- 
pment of the vegetable and animal kingdoms. Whether the 
@f variations of the forces of light and heat, in so far as 
fies nd upon the eccentricity of the earth’s orbit, are suf- 
ficken to account for the changes which geology shows tohave = 
Ken place during the ages that are past, we do not purpose 
Row to determine. Nor do we purpose to give the necessary 
