land 
PROCEEDINGS OF SOCIETIES. 26/ 
A vote of thanks to the Abbé Rénard for his communication was 
carried by acclamation. 
The President said that the subject of the mineralogical consti- 
tution of these rocks was most important, and they were of much 
interest to English geologists, seeing that there were none at all like 
them to be found in this country. The occurrence of garnets in them, 
however, need not surprise, because they were frequently found in the 
slate rocks of our own lake districts, though perhaps not quite in so 
great a quantity. He thought that the slates of this character must 
be looked upon as thoroughly metamorphic, although they were not 
generally considered so; and therefore he regarded it as highly 
desirable to work out the subject in order to make out if possible 
what changes had taken place in the substances composing them. 
He might mention that the Abbé Rénard was the author of some 
of the very beautiful illustrations of the microscopical structure of rocks 
which were exhibited at the Loan Collection at South Kensington. 
A paper by Mr. H. J. Slack (who was unfortunately prevented by 
indisposition from being present at the meeting), “On Krupp’s Silica 
Cotton,” was taken as read, the President giving a summary of the 
general results, and explaining that it referred to the minute fibrous 
particles produced when a powerful blast was directed upon a quantity 
of melted glassy furnace-slag. Many of the little particles so pro- 
duced were like small shots, with one or more fine thread-like tails 
attached to them, and when the process was carried on in the open air, 
the whole place became filled with these minute particles, which were, 
from their hardness and sharpness, extremely detrimental to the lungs 
of persons who inhaled them. Mr. Slack’s paper had reference to the 
various shapes of the little spheres, and to the remarkable regularity 
which existed amongst them, as well as their curious markings. The 
President said that these spheres are of great interest in connection 
with the structure of meteorites, and might explain the formation of a 
number of round glassy particles which he had often found in those 
bodies. Nearly all the peculiarities of the artificial product may be 
referred to the tendency of a liquid to collect into spheres and of a 
viscuous glass to be drawn out into fibres. Mr. Slack’s paper was 
accompanied by some illustrative drawings; and a slide, in further 
illustration of the subject, was exhibited in the room. 
The thanks of the meeting were unanimously voted to Mr. Slack 
for his communication. 
The President said that they had received another paper to be read 
that evening ; 1t was from Mr. Clifton Ward, “ On the Lower Silurian 
Lavas of Eycott Hill, Cumberland.” The paper was rather too long 
to read in extenso at that late hour of the evening, but Mr. Stewart 
would read the introduction and the general conclusions. The whole 
paper would be printed in the Journal (at p. 239). 
Mr. Charles Stewart then read so much of the paper as explained 
the leading results. 
The President proposed a vote of thanks to Mr. Clifton Ward for 
his paper. The subject was one of considerable importance, because 
at one time it was thought that there was a great deal of difference 
between the composition of the ancient and modern lavas. This was 
