DR T. THOMSON'S Analysis of some Minerals. 469 



Soft enough to be scraped by the nail of the thumb. 

 Opaque. 



Specific gravity 2.353. 



By exposure to a red heat its colour was changed into brown. 

 It retained its asbestous structure, but had become brittle and 

 easily reducible to powder. 12 grains by this treatment lost 

 3.56 grains, which is equivalent to 29.66 per cent. This loss was 



pure water. 



[$'','. i !i- . . ' : 'Ji 



It dissolved in nitric acid, without effervescence, leaving a 

 little silica. 



On subjecting it to analysis, I obtained the following consti- 

 tuents, 



Magnesia, . . . . 51.721 



Silica, . . } "'' ". . 12.568 



Peroxide of iron, . . 5.874 



Water, . <?* <!<! <!><.. 29.666 



99.829 

 This is equivalent to 



20.75 atoms magnesia, 



6.25 atoms silica, 



1 atom peroxide of iron, 

 26.333 atoms water. 



This might be considered as, 



20.75 atoms protohydrate of magnesia, mixed with 

 6.25 atoms silica, 

 1 atom peroxide of iron, 

 5.58 atoms water. 



3 N 2 



