344 Mr. D. Forbes's Researches in 



The analysis was conducted precisely as in the case of the spe- 

 cimens from Clogau previously examined. 



20-16 grs. afforded 17*71 grs. metallic gold, 3*89 grs. chloride 

 of silver, 0*09 gr. insoluble quartz, and 0*10 gr. sesquioxide of 

 iron. 



These results, when calculated, will give the composition as 

 follows : — 



Gold 17-71 84-89 



Silver ....... 2-92 13*99 



Iron 0-07 0*34 



Quartz 0-09 0*43 



Traces of copper and loss 0*07 0*35 



20-86 HXKJO 



Several of the larger spangles of gold appeared of a peculiarly 

 rich colour, owing to their being coated with, as it were, a var- 

 nish or thin film of sesquioxide of iron, which persistently ad- 

 hered to their surface, and probably was the source of part, if 

 not of all the iron found by analysis. This coating was no 

 doubt the cause of this gold appearing to the eye considerably 

 richer than it actually turned out to be on assay. 



Titanoferrite. 



When engaged in the examination of the eruptive rocks of the 

 South Staffordshire coal-field*, the author found that these 

 basaltic or doleritic rocks, locally known by the name of Rowley 

 Rag, invariably contained a small but constant amount of a heavy 

 black metallic mineral, strongly attracted by the magnet, and 

 which, therefore, was generally regarded as magnetite or mag- 

 netic oxide of iron. 



As the analyses made of the rocks themselves always showed 

 the presence of the comparatively rare element titanium, it at 

 once appeared probable that this mineral would turn out to be 

 titanoferrite — a compound of titanium, iron, and oxygen, the 

 exact chemical constitution of which is not yet altogether agreed 

 upon by mineralogists. 



After a fruitless search in the various quarries of this rock, 

 which are opened at many places along the range of the Rowley 

 Hills, this mineral was nowhere found to present itself in speci- 

 mens of a tangible magnitude, and was never observed except in 

 microscopic grains disseminated throughout the rock itself. In 

 order, therefore, to procure an amount sufficient for its exami- 

 nation and analysis, a perfectly fresh part of a basaltic column 

 from the Turners Hill quarry (possessing a specific gravity of 



* British Association Report for 1865, Sects, p. 53, " On the Igneous 

 Rocks of South Staffordshire." 



