Reviews — Canadian Geological Survey. 273 



It may be pointed out that the emission of a secondary exhalation 

 as a result of atmospheric oxidation does not necessarily entail any 

 expansion at all, since carbon dioxide and sulphur dioxide occupy no 

 greater volume than their contained oxygen. 



Gas generators. — Brun suggests that the volcanic exhalations result 

 in the main from reactions between silico-chloride of calcium 

 (Si0 3 Ca 3 Cl 3 ), nitride of silicon and various hydrocarbons. Such 

 speculations are of necessity unconvincing, but they are supported 

 by a large number of strikingly interesting experiments. In regard 

 to the origin of sulphur and its compounds in volcanic exhalations 

 he expresses no definite view, but at the same time he has several 

 important observations to record respecting the mode of occurrence of 

 the element in nature. 



An effect of high pressure. — The gases obtained experimentally 

 in vacuo are the same as those which actually issue from volcanoes. 

 There is only one exception : cai'bon monoxide, a characteristic gas of 

 the laboratory experiments, is extremely rare in nature. Its absence 

 may be accounted for on two heads. In the first place it is easily 

 burnt to carbon dioxide on contact with air, and in the second place, 

 according to Briner, it readily decomposes to carbon dioxide and 

 carbon on heating to 300° C. at 600 atmospheres. It is quite possible, 

 therefore, that the rarity of carbon monoxide in volcanic exhalations 

 is due to the high pressures ruling during the emission of the latter. 



E. B. Bailey. 



{To be concluded in our next Number.) 



II. — Canadian Geological Survey. 



REPORTS on parts of the North-West Territories to the west of 

 James Bay and south of Hudson Bay, have been prepared bv 

 Mr. W. Mclnnes and Mr. A. W. G. AVilson (1910). The rocks 

 encountered during their explorations and traverses include Archaean, 

 Lower Huronian (?), Silurian (Niagara), Pleistocene, and later 

 deposits. A list of Silurian fossils obtained along the Winisk River 

 is given on the authority of the late J. F. Whiteaves. Observations 

 are recorded oh the natural history, climate, archaeology, etc. ; and 

 there are lists of recent land and freshwater mollusca collected by 

 Mr. Wilson and named by Whiteaves. 



The "Geology of the Nipigon Basin, Ontario", by Mr. Wilson 

 (Memoir No. 1, 1910), is illustrated by a map containing a good deal 

 of detailed work, as well as data obtained by traverses. The rocks 

 are all grouped either definitely or doubtfully as pre-Cambrian. The 

 greater part of the district is underlain by Laurentian gneisses and 

 batholithic invasions of granite, which penetrate an apparently older 

 series of greenstones and schists, classed as Kjeewatin. Infolded with 

 the Keewatin rocks, and probably belonging to the higher portion of 

 the series, is an Ironstone formation. The Keewatin Series also 

 contains bands with quartz stringers and veins that yield small values 

 in gold. These more ancient rocks are all intensely metamorphosed, 

 and the prevailing structures are nearly vertical. Upon them rest 

 the Keweenawan (Nipigon formation), consisting of conglomeraets, 



DECADE V. — VOL. VHI. — NO. VI. 18 



