Mr. Gourlie on the Fossil Plants in the Glasgow Gtclogieal Museum. 106 



specimen contains about 10 per cent, more silica, and that magnesia, 

 of which there is 25 per cent, in natural Asbestus, is replaced by the 

 protoxide of manganese. Now, it is well known that the protoxide 

 of manganese is isomorphous with magnesia, and hence this replace- 

 ment of the one by the other is at once explained. I apprehend the 

 substitution of manganese for magnesia will be found much more fre- 

 quent in the mineral kingdom when minerals are submitted to improved 

 methods of analysis. The occurrence of Asbestus in an iron furnace 

 affords a beautiful proof of the igneous origin of tliis substance. 



XXX. — Notice of New Zealand Minerals. 



Dr. R. D. Thomson showed a specimen of Phosphate of Iron, or na- 

 tive Prussian blue, from New Zealand, presented to him by Dr. Ernst 

 Dieffonbach, Naturalist to the New Zealand Company, which had been 

 analysed in the University Laboratory, at his request, by Mr. Robert 

 Pattison. Its constituents were — 



Water, 284 



Organic matter, .... 2*8 



Silica, 5-2 



Phosphate of Iron, . . .62-8 



"99^ 

 Dr. Thomson also exhibited a deposit from a hot spring in the interior 

 of the same island, which Mr. Pattison found to have a specific gravity 

 of 1-968, and to consist of — 



Silica, 77-35 



Alumina, 970 



Peroxide of Iron, . . . 3-72 



Lime 1'54 



Water, 766 



9*998 

 From the statement of Dr. Dieffenbach, it appears that the greater 

 part of the interior of New Zealand is of a volcanic nature, and 

 abounds in hot springs. 



\6ih Fehruaryt 1843, — The President in the Chair. 



Messrs. Andrew Craig, John Heugh, and George Wilson, were ad- 

 mitted members. 



The following communication was read : — 



XXXL — Notice of the Fossil Plants in the Glasgow Geological Museum. 

 By William Gourlie, Jun. Esq. 



Most of the members of this Society are aware, that previous to tho 

 meeting of the British Association in Glasgow a Committee was 



