1815.] Transactions of the Geological Society, Vol, II. 65 
which have been deposited at the same time with the clayey basis. 
I consider traptuff not as a breccia, but as an original rock. Dr. 
M. observed rolled masses of granitey gneiss, and other primitive 
rocks upon Staffa. He supposes that this had escaped the ohserva- 
tion of preceding observers. But this is a mistake. J am pretty 
sure that the same observation was made by Faujas de St. Fond; 
though I have it not in my power at present to consult his book. 
Mr. Mills mentions the same thing in his paper published in the 
- Philosophical Transactions, 1790, vol. Ixxx. p. 75. 
XXILL. On Vegetable Remains preserved in Chalcedony. By Dr. 
Macculloch.—Nothing is more common than to observe in agates 
arborizations having a close resemblance to plants. The same thing 
occurs in chalcedony. Daubenton many years ago wrote a paper 
on the subject, in which he even names the species of plant con- 
tained in the chalcedony which he examined. Dr. M. likewise 
collected a great many of these chalcedonies, and the result of a 
carefu] examination satisfied him that true plants, chiefly confervas 
and mosses, oecur in chalcedonies ; though very perfect imitations 
of them are often produced by chlorite. To distinguish the true 
plant, he applies sulphuric acid to the mineral. If the acid be 
blackened he concludes that a true vegetable exists in the stone; if 
not, he considers the appearance as owing to chlorite. It would be 
difficult to convince me that such delicate. vegetables.as confervas 
and mosses can exist in chalcedonies, without so much as their co- 
lour or texture being altered. I am rather disposed to ascribe 
these appearances to manganese, iron, &c. occasionally mixed with 
bitumen. This bitumen I conceive colours the sulphuric acid, 
and leads to the conclusion that vegetable matter is present. The 
fact that some of the lines in agates are blackened by sulphuric 
acid, mentioned by Dr. Hamel in a late number of the Annals, 
shows that bituminous matter is a pretty frequent constituent of 
agates. 
XXIV. On the vitreous Tubes found near to Drigg in Cumler- 
land. Compiled by the secretaries from several communications. 
—These tubes have been found in hillocks of drifted sand at the 
mouth of the Irt in Cumberland. The first account of them was 
sent to the Society in 1812 by Mr. Irton of Irtonhall, Cumberland. 
Three were found ina single area of 15 yards, forming a_hillock 
elevated 40 feet above the level of the sea. ‘The diameter of each 
was about an inch anda half. Within they consist of a very hard 
glass, which strikes fire with steel. One of them was traced to the 
depth of 30 feet without terminating, though it became smaller. 
The sand falling in prevented the continuance of the excavations : 
the sand consists of quartz mixed with grains of horn-stone por- 
phyry. By the blow-pipe urged by a stream of oxygen gas, this 
sand was imperfectly vitrified, so as to resemble the inside of the 
tubes. The most probable opinion is, that these tubes have been 
formed by the action of Jightning. | 
Vout, VJ. N° J, Dy 
