136 Proceedings of Philosophical Societies. [Frs. 
akind of tube with an operculum at the top. They contain a sac- 
charine liquid which allures the insect. It lingers some time on the 
margin of the leaf, but at last ventures in, and is drowned in the 
liquid, being unable to make its way up the tube, which is beset 
with hairs pointing downwards, and preventing its escape. The 
number of flies destroyed by falling into these leaves is very great. 
They are sometimes placed in rooms for the purpose of getting rid 
of flies. 
On Tuesday, Jar © 1816, a paper by M. Richard, of the 
French Institute, \ .-uu, containing a description of two new 
species of American plants, the xylopia sericea and oxandra lauri- 
folia. 
GEOLOGICAL SOCIETY. 
June 16, 1815.—A paper, entitled Description of a New Ore of 
Tellurium, by Professor Esmark, of Christiana (accompanied by a 
specimen), was read. ‘This ore occurs in hexagonal plates, of a tin- 
white colour. When exposed to the blow-pipe, it exhibits all the 
characters of tellurium, and there remains behind a globule of 
silver. It is found in the Oundal copper-mine, accompanied by 
copper pyrites and by molybdena. 
A paper on the analysis of a Swedish mineral, supposed to be 
felspar, by John F, W. Herschell, Esq. was read. The former 
part of the paper consists of observations, supported by examples, 
for the purpose of showing that silica acts as a weak acid in the 
composition of mineral substances, and that it combines with the 
other earths, and with metallic oxides, in definite proportions. The 
mineral itself, a detailed account of: the analysis of which is given 
in the latter part of the paper, approaches nearly in. its composition 
to fibrolite, its ingredients with their proportions being as follows: , 
AION, sepsis oy 10 -preracel te serecde bo ebiwe G4'22 
BLIGE 4: oo pigihtee este siisle Quek ais, de alk ames 34°03 
Oxide of iron and lime, besides a trace of 175 
oxide of manganese and potash ..... : 
100 
A letter from S. Solly, Esq. to the Junior Secretary, dated 
Christiana, Dec. 6, 1814, wasread. In this letter some particulars 
relative to the junctions of the shell lime-stone and trap in the 
vicinity of Christiana are related, and their application to a parti- 
cular theory of Mr. S. on the origin of the compact and porphyritic 
traps. 
A paper, entitled An Account of some Attempts to ascertain the 
Angles of the Primitive Crystals of Quartz, and of the Sulphate of 
Barytes, by W. Phillips, Esq. M. G. S. was read. M. Haiiy, in 
his Tableau Comparatif, has stated the angles of the primitive 
crystals of quartz at 94° 24’ and 85° 36’. 
Mr. Phillips, in his trials with the reflecting goniometet on some 
