268 Proceedings of the Boyal Physical Society. 
by placing vegetable matter in moist clay, and exposing to 
heat. Daubree's observations made at the thermal springs 
of Plombieres were next mentioned. These issue, with a 
temperature of about 172° Fahr., from a porphyritic granite 
in the mountains of the Voges. To convey the water of 
the springs to the baths, which the Eomans had built there, 
a structure of brick and sand had been erected. Through 
this the water had trickled. On breaking into the mass 
numerous minerals of the zeolite family were found, but 
chiefly Apophyllite and Chabasite. Mr Livingston then 
mentioned the extensive changes effected by the juxtaposi- 
tion of certain rocks, and especially the phenomenon termed 
Endomorphism by Fournet. He then discussed the bearing 
of these and other facts, and showed that, though the hypo- 
thesis of a central fire would undoubtedly explain much, 
yet that it would not all. If heat were the only agent in 
these changes, he asked why did they not take place accord- 
ing to the known laws of the propagation of heat and the 
conductibility of rocks ? That water had to do in effecting 
these changes was evident from the occurrence of chiasto- 
lite, augite, garnet, and felspar in sedimentary rocks. The 
presence of water chemically combined in the masses ejected 
by volcanoes was a proof that it played an important part 
in the phenomena that take place at great depths. He then 
referred to the facility with which minerals, and especially 
the silicates, can be formed when water is present, to Dau- 
bree's production of Wollastonite,to his process of forming the 
anhydrous silicates in the moist way, and his production of 
a substance like mica and chlorite. Mr Livingston believed 
that these researches invite us to hesitate before we commit 
ourselves to the views of the igneous rocks at present in 
vogue, and expressed his conviction that the faith of geolo- 
gists, after much weary tossing between fire and water, would 
finally settle down somewhere between these two extremes* 
A conversation followed on the plutonic and aqueous 
agencies in the formation of rocks, and on the probable 
aqueous origin of granite, in which Professor M'Donald, Mr 
Alex. Bryson, and others, took part. 
