VII... Chemical Analysis of a. BuAck, Sanp, from the River 
» Dee in Aberdeenshire ; and of a CoprEr:Orxe, from Ar- 
 threy in Stirlingshire. By Tuomas Tuomson, M.D. 
* Lecturer on Chemistry, ‘Edinburgh. 
[Read 18th May 1807.] 
HE fpecimen which formed the fubject of the firft of the 
following analyses, was brought from the banks of the river 
Dee, about feven years ago, by my friend Mr James Mitt, who 
at that time refided in Aberdeenfhire. By him I was informed, 
that confiderable quantities of it are found in different parts of 
the bed of that river,—that it is called by the inhabitants zron- 
‘sand,—and that they ufe it for fanding newly written paper. I 
tried fome experiments in the year 1800, in order to afcertain 
its nature} but’was ‘too little fkilled at that time, both in mi- 
netalogy and praétical chemiftry, to manage an analyfis of any 
confiderable difficulty. 
’ "Tue black’ powder is mixed with a good many fmall whitith, 
reddifh, and brownifh grains, which, when examined by means 
of a glafs, prove to be pieces of quartz, felfpar, and mica. From 
this it would appear, that the fand of the river Dee confifts 
chiefly of the detritus of granite or gneifs. 
> ‘WHEN a magnet is pafled over the fand, fome of the black 
grains adhere to it, and are by this means eafily obtained fepa- 
Ts2 rate. 
