Vol. 58.1 ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxill 
took place. It was a laborious research extending over many years, 
and involving more than 500 experiments, He sums up his results 
as follows :— 
‘ By this joint action of heat and pressure the carbonate of lime, which had 
been introduced in the state of the finest powder, is agglutinated into a 
firm mass, possessing a degree of hardness, compactness, and specific gravity, 
nearly approaching to these qualities in a sound limestone; and some of the 
results by their saline fracture, by their semi-transparency, and their suscepti- 
bility of polish, deserve the name of marble. The same trials have been made 
with all calcareous substances; with chalk, common limestone, marble, spar, 
and the shells of fish.’ ? 
But Hutton’s theory, even after this striking verification by Hall, 
attracted little attention until it was resuscitated by Lyell. Then 
it began to spread. In 1856,‘ The Metamorphism of Rocks’ was 
made the subject of the Bordin Prize by the Academy of Sciences of 
Paris, and two years later the award was made to Daubrée, whose 
classic essay contains an account of the celebrated experiments 
on the effect of superheated water and saline solutions on glass, 
obsidian, and other substances. 
The growth of ideas on the subject of metamorphism has, how- 
ever, been mainly determined byfobservation, and especially by 
the study of the effects produced in connection with the intrusion 
of masses of molten material. Here, again, the example was set by 
Sir James Hall. In his remarkable’paper on ‘ The Vertical Position 
& Convolutions of certain Strata & their Relation with Granite,’ ” 
he says :— 
‘The quality of this stratified mass [the Lower Paleozoic formations of the 
Southern Uplands of Scotland], from one side of the island to the other, seems 
to be uniform throughout, except?in the immediate neighbourhood or contact 
of the granite, where it assumes a micaceous character, approaching to the 
nature of gneiss or mica-slate. This furnishes a most notable indication of 
the action of heat, since the granite, by its local intensity, has performed the 
very effect which Dr. Hutton ascribes to the general heat below, as acting upon 
the lower beds, and converting them@into gneiss.’ 
An immense amount of information’as to the phenomena accom- 
panying the intrusion of igneous rocks has been gained since Hall’s 
time. Innumerable granite-masses have been mapped, and the 
contact-rocks have been examined by modern petrographical methods. 
We are now familiar with the changes which take place in lime- 
stones, dolomites, slates, sandstones, cherts, greywackes, diabases, 
andesites, and many other kinds of sedimentary and igneous rocks 
* Trans. Roy. Soc. Edin. vol. vi (1805) p. 95. 
? Ibid. vol. vii (1812) pp. 106-107. 
