Reviews—Irving’s Chemical and Physical Studies. 567 
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I.—CuemicaL anD PuysicaL STupIEs In THE METAMORPHISM OF 
Rocks, BASED ON THE THESIS WRITTEN FOR THE D.Sc. Decrees IN 
tHE University or Lonpon, 1888. By the Rev. A. Irvine, 
D.Sc. Lond., Senior Science Master at Wellington College. 8vo. 
pp. 1388. Price 5s. [August 16, 1889.] 
HE word “ Metamorphism ” as applied to rocks, in consequence 
of the various interpretations to which it has been subjected, 
is no donbt of great service to slippery disputants. By a judicious 
use of the term some writers can conjure up such a haze as most 
effectually to elude the pursuit of any critic who rashly endeavours 
to run them down. Dr. Irving wishes to put an end to this state 
' of things by fixing such limitations to the meaning of the term as 
would, for instance, prevent people from quoting examples of an 
early stage of ‘‘metamorphism” from such rocks as the Old Red 
Sandstone Conglomerates of Scotland. In this thesis ‘ metamor- 
phism” is to be used to mean only changes in the internal structure 
of rock-masses. The author, however, qualifies this by subsequently 
stating that he is not dealing with the so-called rocks of the syste- 
matist, but rather with principles. Hence, he is disposed to ignore 
the restrictions and limitations which may be convenient in classify- 
ing rocks; and, as to text-books, they appear to arouse in his breast 
feelings akin to those of the Knight of La Mancha at the sight of 
a windmill. 
In his general conclusion as to the diagenetic origin of the so- 
called ‘‘ Archean” rocks we are disposed to concur, although it is 
by no means improbable that many of these rocks may have had 
a very different and much later origin. But it is by no means 
certain that the arguments and peculiar nomenclature of the present 
work will be found, in the sequel, to have strengthened the diage- 
netic as opposed to the metamorphic theory. No doubt those who 
can thoroughly understand the book may derive considerable benefit 
from its perusal. At the same time, the chemical speculations of 
of this author, as to the earlier stages of rock-genesis, appear by no 
means equal in quality to those of Sterry Hunt, though this perhaps 
may be regarded as a matter of fancy, and other readers might 
arrive at a different conclusion. There is a considerable parade of 
chemical knowledge brought to bear upon these points. 
The plan of the treatise is as follows :— 
Paramorphism, or Mineral Change, includes Primary Paramorphism 
or Rock Genesis, and Secondary Paramorphism resulting from the 
gradual alteration of the conditions of rock environment. Metatrophy 
includes changes in the physical character of the rock-masses, whilst 
there is no essential change either in the rock-mass or in its con- 
stituents. Metataxzis is a change of order of the constituents of the 
rock-mass of which the phenomena of slaty cleavage may be taken 
as a typical instance. The author then proceeds to deal with what 
he calls Hyperpheric Change, of which the dolomitization of 
