104 Dr. Bonsdorfs Analysh [Feb. 



The result of this analysis is as follows : 



Silica 49'95 containing 25*11 of oxygen 



Alumina 32*88 15*35 



Magnesia 10-45 4*04 



; Peroxide of iron. . . 5*00 1*53 



Oxide of manganese 0*03 

 Volatile matter .... 1*65 



99*96 



When the composition of this mineral is considered with 

 relation to the electro-chemical theory, and the doctrine of defi- 

 nite proportions, it is evident that the quantities of oxygen in the 

 silica, alumina, and magnesia, are nearly in the proportion of 

 1*4 and 6, and consequently we might express the mineralogical' 

 fotmula by M S- + A A S\ but as the peroxide of iron can 

 only exist in combination with the silica, and as M. Mitscher- 

 lich* has proved that the peroxide of iron gives the same crystal- 

 line forms by combining with electro-negative bodies as alumina 

 4oes, the composition of this mineral will be more properly 



expressed by the following formula M ^- + 4 S— J S, which^ 



when the quantity of oxide of iron remains unchanged, gives the 

 calculated result of the composition of this mineral as follows : 



Silica 49*93 



Alumina 32*60 



Magnesia 10*82 



Peroxide of iron 5*00 



It will be observed that these proportions agree very nearly 

 with the actual results of the analysis. 



II. Mala colit from Tammarej in Finland. 



During a mineralogical tour, I found this mineral in an aban- 

 doned lime quarry, at the village of Tamnaare in the parish of 

 Hvittis. 



It occurs in large masses, accompanied with calcareous spar 

 and noble serpentine. Its colour is white, sometimes greenish 

 white ; it is translucent; the lustre vitreous ; not very hard, giv- 

 ing but few sparks with steel. It has a laminated structure ; 

 the angles of the fragments are similar to those of the common 

 malacolit. Its specific gravity is 3*256. 



Before the blowpipe it melts per se, with slight effervescence, 

 into a translucent glass. It is dissolved by borax, microcosmic 

 •alt, and soda, and forms with them a clear glass. With solu- 



• See Annales do Chimie etde Physique, tome xiv. p. 172, Sur la Relation quiexiste 

 •ntre la Fonne Crystalline, ct les Proportions Chimiquei. Par E. Mitscherlich. 



