147 
Mr. Binney, F.R.S., exhibited a singular mineral which 
Mr. Ward of Longton had found in a nodule of clay iron- 
stone from the North Staffordshire coalfield. At first sight 
it looked like a fossil coral of the genus Cyathopliyllum, but 
on more careful examination it appears to be a mineral mass 
in a semicrystalline state. The form of the mineral appears 
to have been spheroidal with crystals radiating from the 
centre. By the kindness of Dr. Crace Calvert he had ascer- 
tained the specimen to consist chiefly of carbonate of lime, 
carbonate of iron, and phosphate of lime, with traces of 
magnesia, alumina, and organic matter, and ten *per cent of 
silica. 
He also exhibited a beautiful white specimen of carbonate 
of strontia obtained from a vein of carbonate of lime. It 
occurred among the lime in radiated masses similar to those 
of carbonate of barytes as sometimes found in veins of 
sulphate of barytes. This mineral has been found in con- 
siderable abundance, but up to this time it is believed that 
no use has been found for it on a large scale. 
Messrs. Hull and Brockbank exhibited specimens of the 
iron ores referred to in their paper “ On the Liassic and 
Oolitic Iron Ores of Yorkshire and the East Midland Coun- 
ties,” read at the last meeting of the Society. 
Professor Roscoe stated that he had just received a letter 
from Professor Bunsen, announcing the discovery of a most 
interesting and important fact, namely, that the well known 
black absorption lines of the Didymium spectrum, when 
examined with polarised light, vary according to the direc- 
tion in which the light is allowed to pass through the crystal. 
This shows that the position of the black absorption lines is 
in some degree dependent upon the physical structure of the 
body through which the light passes, and is not merely 
determined by its chemical constitution. 
