C 181 ] 
Received December 12, 1765. 
*XXVII. Experiments and Obfervations upon 
a blue Subfiance , found in a Peat-mofs in 
Scotland : By Sylvefter Douglas, Efquire , 
Read February 1 3, y- g ^ H E blue coloured fubftance, 
I /°°- which is the fubjedt of the fol- 
lowing obfervations, and which is now before you, was 
accidentally dug up in the fummer 1759, in order to 
mix with fome other materials for the purpofe of ma- 
nure, to be laid "on fome ground, at prefent in my 
pofleflion, in the north of Scotland, about twelve 
miles from Aberdeen. 
I have not met with a defeription of this fubftance 
in any naturalift. Kentman indeed in a few lines 
mentions a blue earth, which he calls ccernleum Pata- 
vinutn , which agrees with the fubftance I am about 
to deferibe, in one remarkable circumftance j that it 
is at firft of a white colour, and becomes blue only in 
confequence of being expofed to the air. Mr. Da 
Cofta’s ochra friabilis ccerulea -f-, would alfo have been 
found probably to correfpond with it, if a more par- 
ticular account could have been given of the circum- 
ftances in which, it was found, and its appearance 
before the air had adfed upon it. Mr. Cronftedt, in 
* This paper, having being miflaid, could not be printed in the 
Volume of the Philofophical TranCadtions for 1 766. 
f Nat. Hilt, of Foil. p. 103. 
his 
