152 Scientific Intelligence. [Feb. 



Article XVI. 



SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS 

 CONNECTED WITH SCIENCE. 



I. Lectures. 



Mr. Cooper will commence his next Course of Lectures on 

 Chemistry early in the present month, at his house, 89, Strand. 



II. Graphite in Scotland. 



(To Dr. Thomson.) 

 SIR, 



The discovery of graphite, imbedded in micaceous schistus, at 

 Strathfarran, near Beauly, Inverness-shire, has not, I believe, 

 been publicly noticed. Dr. Davidson, Professor of Natural Philo- 

 sophy at Aberdeen, had examined the beds a short time pre- 

 viously to my arrival at that city, in September last : he obligingly 

 communicated to me the following account, and gave me 

 specimens : 



" There are three beds of compact graphite, varying in thick- 

 ness from 15 to 18 inches ; they are separated by intervening 

 beds of micaceous schistus, about four yards in thickness. The 

 beds dip at an angle of about 25°. The schistose laminae of the 

 rock dip in the same direction, and at the same angle. The 

 beds of graphite appear to extend from the top of the hill to the 

 bottom, as far as can be discovered. Workings have been 

 commenced in these beds, but have not been continued far 

 enough to discover what may be the quality of the mineral at a 

 distance from the surface." The specimens given me by Dr. 

 Davidson, though greatly inferior in lustre to the best graphite of 

 Borrowdale, yet possess all the characters of true graphite ; 

 they are soft and sectile, and leave as distinct a mark on paper 

 as the best specimens from Cumberland. These specimens have 

 the curved laminar structure of many varieties of mica slate, and 

 the surface, which is weathered, has a very close resemblance to 

 that rock. Internally, the mineral appears to be composed of 

 minute laminae, like mica, which are, however, true graphite. 



The circumstance of mica slate impressing its form and 

 structure on the imbedded mineral, so different in composition, 

 may appear at first extraordinary ; but it is an effect analogous 

 to what we may observe in other situations. The great unctu- 

 osity of the Borrowdale graphite is, as I have reason to believe, 

 derived from that of a soft adjacent bed which accompanies it. 

 The peculiar unctuosity of the Ulverstone iron ore is derived 

 from the same cause ; and numerous instances might be men- 

 tioned where the quality of metallic ores, and of the metals 

 obtained from them, appear to be affected by the rock through 

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