846 
Proceedings of the Royal Society 
Professor Crum Brown having analysed both balls, reported the 
largest to have a specific gravity of 3*36, and to be composed of 
silica 52*3 per cent, and of pyrites 47 '7 per cent. The smallest had 
a specific gravity of 4 “6 3, and was found to consist of the pure ore 
of white iron pyrites or marcasite, unmixed with any other sub- 
stance. 
Mr Murray, of the “Challenger” Expedition, having kindly under- 
taken to examine the larger ball, reported that a microscopic ex- 
amination revealed that it consisted “ of crystalline particles of 
quartz and marcasite. The marcasite fills the interstices between 
the grains of quartz ; and among the quartz there are pieces of 
mica.” 
Mr Charles Peach at the same time informed the Convener 
that in several districts to the west (viz., Falkirk, Slamannan, and 
Kilsyth) there are beds of shale and coal, containing ironstone 
nodules, known among the miners as “ brassy balls f some of which 
contain marcasite. He added that “ the direction of the strice and 
carry of the boulders in this (the Kilsyth) district is E. or E. 5° K. 
Either of these sources (he remarked) could supply '‘Palls'’' at Leith, 
as they are right in the direction of the “ ice-flow ” {Fourth Report, 
p. 29). 
In consequence of the foregoing information, the Convener went 
to Campsie (about 8 miles K.E. from Glasgow), and in the work- 
ings of coal and shale there he obtained several ironstone balls, 
which, on being submitted to Professor Crum Brown, he reported 
contained almost exactly the same constituents as the specimens 
found at Leith. He added, that “deducting the coaly matter, 
the iron and sulphur were in the proportion in which they are 
generally found in marcasite, viz., iron 45*6, and sulphur 54*8. 
As to chemical compositions, therefore, the small metallic boulder 
may be considered as exactly agreeing with the nodules found in 
the Campsie coal strata.” 
With regard to the larger ball, not so purely metallic, Mr Hutchi- 
son of Carlowrie having accidentally seen in the Convener’s house, 
Edinburgh, the specimen excavated from the Leith boulder clay, 
informed the Convener that balls of the same appearance, and much 
larger, were found in sandstone rocks quarried at Dalmeny and 
Humbie. The Convener thereupon visited these quarries, and 
