244 Scientific Intelligence. 
at the Opal spring of the Gibbon Basin, the latter at the Mam- 
moth Hot Springs. The water from the Opal spring, on concen- 
(common salt) which at the Opal spring amounted to 82:18 
grains in the gallon, while calcium salts are often wholly absent 
or only in traces. In most of the springs a sal esi of silica 
does not take place on cooling, evaporation being necessary. 
esides the ordinary geyserite, — contains usually 9 to 13 
per cent of water, (and the Pealite in which the water is 1 to 6 
per cent), an unstable variety which, liad still moist, makes an 
incrustation looking a little leathery, but dries to a soft, easily 
crumbling m mass, = named, by E. Goldschmidt, Viandite. e 
“steam-dry ” ial was found to afford about 75 per cent 
of water to 20 “Of ae. ; but the describer says that “very 
probably the saree Speer no stability.” 
. On the e of the Glacial Period ; by Suartes V. Woo 
(Geol. Mag., i. rs uly, 1883, pp. 293-302). —The east sonoma 
of this paper is given on page 150. The following is a notice o 
the author’s course of argument prepared for this Journal by Mr. 
McGee. 
In this memoir, which embodies the ccomcloun ideas devel- 
oped during his extended researches in the Newer Pliocene of 
England, Mr. Wood reiterates and accepts as fatal ca the eccen- 
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considerable eget nein we in Green land, despite the low pre 
cipitation there, in proof of the soundness at ‘his view ; from which 
he concludes that the Quaternary ice wa s probably: developed 
under lower temperatures than those now obtaining. In explana- 
tion of the assumed cooling of the earth during the Glacial period, 
