740 REPORT—1899. 
6. Note on Barium Sulphate in the Bunter Sandstone of North Staffordshire. 
By C. B. Wenvp, B.A., LG. 
[Communicated by permission of the Director-General of the Geological Survey.] 
Special attention has been directed by Professor F. Clowes to the deposition 
of barium sulphate as a cementing material of Triassic sandstone near Nottingham, 
and he has mentioned numerous places, on the authority of Mr. J. Lomas, where 
the same mineral has been observed in Triassic rocks,1 
It may be interesting to record another locality. In a cutting of the North 
Staffordshire Railway (Audley Branch), three quarters of a mile south of Alsager 
Road (Talke) Station, a section of Bunter sandstone in Merelake Hill shows the 
cross-like marks common in the Keuper sandstone of Cheshire and Staffordshire, 
and due to barium sulphate crystals. A partial analysis, made by my friend Mr. 
R. Hornby, of the Red Bunter sandstone of Merelake Hill, showed a considerable 
quantity of barium sulphate. Occasional veins filling joints consist of baryto- 
celestite, which may also be seen in other sections of the Bunter of Merelake Hill, 
7. Report on Seismological Investigations. See Reports, p, 161, 
8. Interim Report on the Structure of Crystals, 
9. Report on Life-Zones in British Carboniferous Rocks. 
See Reports, p. 371. 
FRIDAY, SEPTEMBER 15. 
The following Papers and Reports were read :— 
1. The Photo-micrography of Opaque Objects as applied to the Delineation 
of the Minute Structure of Fossils. By Dr. ArTHuR Rows, F.G.S. 
The object of the paper is not to enter into minute technical details of the 
process, but rather to demonstrate upon the screen the scope and limitations of the 
photo-micrography of opaque objects. A contrast was drawn between the 
technique employed in the case of transparent and opaque objects, and it was 
pointed out that, simple as are the broad principles of the latter, the application of 
these principles is a very difficult and tedious matter. Allusion was made to the 
methods used by the author, and the advantages of various lenses and illuminants 
were discussed. ' 
The author stated that incandescent gas had proved quite satisfactory in his 
hands, and that it had been used throughout all his experiments. It was pointed 
out that rapid exposure was no object, and that it was useful to havea light which, 
while sufficiently white and powerful for all purposes, gave one ample margin 
wherewith to vary exposures, and that the real difficulty lay not so much in the 
choice of an illuminant as in the way in which it was managed. The lighting of 
an object would always be a somewhat tedious process, and each specimen had to 
be treated on its merits. 
The limitations to the power of a lens were mentioned, and it was stated that 
it was impossible to expect any lens to focus details lying on separate horizontal 
planes. An instance of this difficulty was furnished by the ambulacral grooves of 
' Proc. Roy. Svc., vol. \xiv. p. 374. References to previous papers are given in 
this article. 
