the Analyses of M. Klaproth. 79 



Tlic sandy substance, or loto, contained then In 100 parts 

 Silex ----- 54 

 Alumina - - - - 16 



Oxide of iron _ - - 3 



Sulphur - - - - 8 



Sulphate of lime - - - 5 



86 



The quantity of sulphurated hydrogen being veiy incon- 

 siderable, the greater part of the loss arises, no douijt, from 

 the water. 



Analysis of the Salt of Idria 2fith capillary Filaments. 



The capillary salt of Idria {Holotricum Scnpopolii) which 

 is found in fissures of the argillaceous schecferthon schist, 

 mixed with the aluminous schist of the mines of Idria, is 

 of a silver-white colour, and forms needle-like or capillary 

 crystals, which sometimes are more than two inches in 

 length. Hitherto they have been considered to be feathered 

 alum, composed of sulphuric acid, alumine, lime, and u'on, 

 according to Scopoli. But the analysis of Klaproth has 

 shown the falsitv of this opinion. 



The result of this analysis proves that the salt of Idria 

 with capillar)' filaments contains neither alumine nor lime, 

 but that it is a natural compound of sulphate of magnesia, 

 containing a small quantity ol the sulphate of iron. 



Analysis of the Feathered yllum of Frayenwald. 



The feathered alum, which is formed in part in the quar- 

 ries of argillaceous schist of Frayenwald, and particularly 

 by their decomposition in the open air, has a white colour 

 inclining to gray. It is composed of capdlary filaments 

 often crooked, united sometimes in bundles not very close, 

 and sometimes cemented, and forming a crust : it has a 

 moderate silky splendour. 



A hundred parts of this feather alum contain 

 Alumine ------ 15'25 



Oxidulous iron ----- 7.50 



Potash, sulphuric acid, and water of crystallisation 75-00 



100 



Analysis of Mtlilite. 



It is to the celebraied mineralogist of Freiberg that \va 

 have been indebted upwards of ten years for the kno'v ledge 

 cf this fossil. The constituent principles of it have been 



loo 



