PROCEEDINGS 



OP THE .< 



PHILOSOPHICAL SOCIETY OF GLASGOW. 



FORTY-FIRST SESSION, 184243. 



CONTENTS. 



Dr. Thomson's Notice of some New Minerals, 61 



ListofOffico-Bearers of the Society for 1842-43, 68 



Notice of some recent additions to Chemistry, 68 



2d November, 1842, — The President in the Chair. 



Dr. Balfour alluded to some experiments recently made, which 

 showed the innocuous nature of liquid muriatic acid applied to the 

 roots of plants. Ho exhibited specimens of cocoa nuts in various 

 stages of vegetation, and a portion of pith used, when cut into thin 

 slices, for making rice paper. 



The following paper was read : — 



XX. — Notice of some New Minerals. By Thomas Thomson, M.D., 

 F.R.S., L. & E., M.R.I.A., Regius Professor of Chemistry. 



One of the most common and important minerals is felspar, which 

 constitutes the principal constituent in granite and gneiss, and, 

 together with hornblende, forms the rocks so prevalent in this part of 

 Scotland, — I mean greenstone and basalt. Felspar is a double salt, 

 being composed of three atoms of tersilicate of alumina, and one atom 

 of tersilicate of potash. Sometimes the potash is replaced bj soda. 

 The mineral, in that case, is distinguished by the name of albite, and 

 differs in the shape of its crystals. 



Three of the minerals which I mean to notice at present, are con- 

 nected with felspar, though they differ from it in their composition. 



1. Erythrite. — The first species which I shall mention, is erythrite. 

 It occurs rather abundantly in the Kilpatrick hills, and also in the 

 amygdaloid on the south side of the Clyde, near Bishoptown. I do 

 not know who first noticed it, but it was brought to me some years 

 ago, as a new mineral, by Mr. Clachers, a mineral dealer in Old Kil- 

 patrick. I call it erythrite on account of the flesh-red colour which 

 distinguishes all the specimens which I have seen. 

 No. 4 



