66 Scientific Intelligence. 
In Chapter I a nature of the inquiry in hand is stated and 
reference made to the older investigators, Spallanzani, Dolomieu 
and Scrope. Chaptes Ii deals with the nature of volcanic action, 
illustrated by the ordinary phenomena of Stromboli an 
eruption of Vesuvius in 1872, and in each case the action is attrib- 
uted to the elastic force of confined steam. Chapter III describes 
the characteristics, chemical, mineralogical, and microscopical, of 
the lavas, while Chapter IV discusses the other r ejected ma aterials, 
scoria, pumice, etc., as also the change of form in volcanoes result- 
ing from ejections of lava and scoria, ee by Monte Neuvo, 
and by the history of changes in the cone of Vesuvius itself, 
In Chapter V the internal structure is na sgl as shown in the 
Kammerbiihl in Bohemia, in Vulcanello and in the volcanic wrecks 
of the islands of Mull and Skye. In this comection the method 
of formation of a cone from scoria is experimentally “aunt by 
the mode of deposition of ee blown vertically from an orifice 
in a horizonta fa and the formation from viscid lava, aby soft 
sealed forced through a ater 6 ening, as devised by Dr. 
Reyer. In Chapter VI the author discusses the structures built 
up about the vents, the cones of scoria, tufa or lava and their vary- 
ing forms, the parasitic cones formed by lateral openings along 
fissures in the sides of the main cone, the change of position of 
the vent gts such fissures, the crater-rings and lakes, mud-vol- 
canoes, e 
Chaser VII gives the life history of the sepa erorwe st uw 
probable order of the phenomena, from the first issue of the 
and gases from the rent in the earth’s crust, ete Heh the eruiptiot 
of andesitic and cr i lavas, to the basaltic or basic lavas, 
the building of the cone, the intrusion of lavas between the 
aioe tt strata foxtaitag taseulitds: and across the strata forming 
es, the appearance at first of the acid gases at high tempera- 
‘bon 
: rings, until all manifestation of igneous agency disappears and 
e cycle is com 
 Ohapter Vill ‘peaks of the distribution of volcanoes; that of the 
300 or 350 active volcanoes, the majority on islands, arranged 
in lines thousands of miles dong, and all near the sea except two 
or three in Central Asia. it may be stated here, that advices 
ages was both in its natu in roducts similar to that of 
our own day. Chapter X illustrates the part played by be ges 
in the economy of nature, by the growth of the Alpin 
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