334 W. Hopkins on Changes of Climate. 
The oxyd of nickel may be in slight excess. The proportion 
of equivalents is, 
SiO MgO CaO NiO C02 HO 
1 8 4 
If we may theorize upon such a complex composition, I would 
suggest as the most likely grouping of the mixture: 
4(2Ni0, CO2, HO) Emerald nickel (pure). 
6(Mg0O, SiO:, HO) Meerschaum. 
3Mg0O, 28103 Augite. 
I have not found a single specimen, which upon treating with 
acid, will not show a white talcose residuum, which appears to 
be Meerschaum, and not Marmolite as I had at first supposed. 
ite.—It is found in crystalline masses with mamillary 
surfaces lining cavities and fissures in the serpentine rock near 
It yielded : 
Carbonate of lime, . : : 51:90 
Carbonate of magnesia, : ; 46°86 
Carbonate of iron, . } ; 1-24 
100-00 
CaO, CO2 +MgO,COz. Although magnesia is in very great ex- 
Arr. XXXVII.—On the Causes which may have owned 
Changes in the Earth’s Superficial Temperature; by "- 
Hopkins, Esq., M.A., F.R.S., Pres. G.S., and Pres. Cambridge 
Phil. Soc. 
(Concluded from p. 259.) é 
3. Discussion of the Relative Claims of the preceding Hypotheses. 
Piers ali idered eses discusse 
__ + Have already stated that I considered the oid peg account for 
Texas, and that surrounding the chromic iron at Wood’s Mine. 
Id 
