338 
Falconer), and illustrated his communication by specimens of the 
plant, by photographs, and by drawings from the accurate pencil of 
Dr Greville. 
2. On the Composition of the Glassy Surface of some Vitrified 
Forts. By Thomas Bloxam, F.C.S., Assistant Chemist to 
the Industrial Museum of Scotland. 
The present paper was undertaken at the suggestion of the late 
Professor George Wilson, as forming an interesting inquiry, both to 
the antiquarian and the chemist, and as a sequel to the paper upon 
old Scotch glass, communicated by me to this Society some time 
since. 
The investigation had for its object, — 
1 st, To ascertain the exact composition of the glassy surfaces of 
the various specimens. 
2d, The composition of the rocks upon which the glass was formed. 
3 d, To account for the formation of such glass by the information 
afforded by the first two inquiries. 
Vitrified forts, or sites, as some prefer to call them, are spaces of 
ground enclosed by a wall composed of pieces of rocks placed upon 
each other without mortar, and the surfaces of which are covered 
with a glassy matter. It is scarcely the province of the chemist to 
speculate as to the purpose for which these sites were erected, or the 
manner in which the vitrification was brought about : we will there- 
fore proceed with the inquiries set forth at the commencement. 
Of the many vitrified forts existing in Scotland, two of the best 
were selected for investigation — the one, “ Duno’deer, ” from Aber- 
deenshire, kindly forwarded by Mr Stuart of the Society of Anti- 
quaries ; the other, “ Knockfarrel,” from Strathpeffer, Boss-shire, 
procured for me by my friend Dr M. Thomson. 
Both these specimens exhibited vitrification in a marked degree. 
The specimen from Duno’deer presented two surfaces of a vitrified 
nature, the one being more porous in appearance than the other ; 
separate portions of these surfaces were carefully broken off for 
analysis, and distinguished as upper and under surface, the under 
one being the more porous. The specimen was coated with moss 
in parts, but these were excluded from the quantity selected for 
analysis. The vitrified surfaces were spread over rocks of different 
