PETROLOGICAL ABSTRACTS AND REVIEWS 274 
Day, A. L., AND SosMAan, R.B. “The Melting Points of Minerals 
in the Light of Recent Investigations on the Gas Thermome- 
ter,” Amer. Jour. Sci., XXXI (1911), 341-40. 
The determination of a new thermometer scale (described in a pre- 
vious article) was based on investigations on the gas thermometer, * 
which resulted in the attainment of a greater accuracy between 400° 
and 1,150°, and the extension of these temperatures by the extrapolated 
curve to 1,550. with an absolute accuracy of 2° at that temperature. 
_Upon the more accurate data thus afforded the melting and inversion 
points of a number of minerals have been reinterpreted, and are here 
given. The tables are prefaced by certain definitions: thus, melting- 
point is defined as the point at which a mineral changes from a crystalline 
to an amorphous (liquid) state; inversion point as that at which it 
passes from one crystalline state to another; and the difference between 
the melting interval of slow melting pure compounds, such as quartz, 
and of mixtures of solid solutions, such as plagioclase, is discussed. 
G. S. ROGERS 
DEWweEy, HENRY, AND FLETT, JOHN SmiTH.. “On Some British 
Pillow-Lavas and the Rocks Associated with Them,” Geol. 
Mag., VIII (May, 1911), 202-9; (June, torr), 241-48. 
The basic submarine lava flows form an important series among the 
Paleozoic igneous rocks of Great Britain, appearing in the pre-Cambrian 
and in all the Paleozoic systems except the Upper Silurian and the 
Permian. In most cases they show more or less of a pillow structure, 
are as a rule very much decomposed, and are characterized by feldspars 
rich in soda. The name spilite is generally applied. Under this name 
is described a rock of variable texture, of which the chief components 
are a soda-rich feldspar, pale brown augite, in some cases remains of 
olivine, and a fair amount of glassy base which is now wholly devitrified. 
The feldspar, especially in the more decomposed specimens, is albite 
and appears peculiarly fresh. From this, and other evidence, the authors 
argue that much of the albite is secondary and that it probably belongs 
to a pneumatolytic phase immediately following the extrusion. Asso- 
ciated with the spilites are intrusive rocks of a great variety of types— 
picrite, diabase, minervite, quartz diabase, heratophyre, quartz kera- 
tophyte, soda felsite, and albite granite—ranging from ultrabasic to 
acid in composition. 
Accepting as established the division of the eruptive rocks into two 
