430 On the ROCKS in the . 
ftained with ferruginous matter. This fact feems connetted . 
with the fingular appearances, which occur in the vein of green- 
ftone, at the level of the junction of the fandftone ftrata with 
the incumbent bed. 
Wirnour offering any remarks on a faci as yet fo infulated, 
[ content myfelf with merely mentioning it, in hopes that fimi- 
lar appearances may prefent themfelves to geologifts in other 
quarters, and perhaps throw fome light on a phenomenon, 
which by farther elucidation may prove interefting. 
BeroreE I clofe this paper, I fhall take the opportunity of pre- 
fenting to the-Society, two fpecimens which were given to 
me by Sir Grorce Mackenziz, and which I efteem of con- 
fiderable value; one of theni, a fragment of the rock of Salif- 
bury Craig; the other, of the Calton Hill, marked im: the 
handwriting of the late Dr'Kennepy, as the fubftances he ana- 
lyfed, and of which an account was given in the 5th volume 
of thefe Zraasactions. The great variety in the rock, both 
of Salifbury Craig and Calton Hill, makes it of importance to 
afcertain with precifion the kind employed in’the refearch of 
that celebrated chemift; and as'the moft proper place for their 
reception, I depofite them in the cabinet of this Society, along. 
with my own collection, under the Nos. 77, and. 78. 
roth 
