1835.] Native Sulphate of Alumina and Iron, 57 



3. Berthier has published the analysis of a hair salt, 

 (Thomson s Inorganic Chemistry, ii. 768.) consisting of 

 Sulphuric acid . . . 34*4 

 Protoxide of iron . . 12* 



Alumina 8*8 



Magnesia 0*8 



Water 44* 



100- 

 corresponding with 1 J Al. S. + /S. + 15 Aq.^ 



4 In the course of an excursion to the eastern parts of 

 the colony of the Cape of Good Hope, H. Hertzog discovered 

 two hair salts in a cave on the Bushman River, 200 feet 

 above its bed, in 30° 30' S.L. and 26° 40' E.L., twenty miles 

 from the sea. The cave was thirty feet wide, seven feet high, 

 and twenty deep, having its upper part coated with feather 

 alum, presenting the appearance of gypsum. The salt is 

 snow-white, fibrous, with a silky lustre, the darker coloured 

 fibres being very elastic. The fibres are partly straight and 

 partly bent. The mineral consists, according to H. Stro- 

 meyer, of 



Alumina 11*515 



Magnesia 3-690 



Protoxide of manganese 2*167 

 Sulphuric acid . . . . 36*770 



Water 45*739 



Chloride of potassium . 0*205 



100*086t 

 which is expressed by 



2J Al. S* + (i M. + 1 mn.) S. -f 20^ Aq. 

 Under the alum a bitter salt is found, which is frequently 

 crystallized in four-sided prisms, and when pure, is white. 

 The mass accompanying the bitter salt is weather-beaten, 

 earthy, and has a slaty appearance, and a greenish-white 

 colour. It contains scales of mica, or talc, which are 

 parallel with its cleavage. H. Stromeyer found it to con- 

 tain silica and alumina in considerable quantity ; very little 



* Ann. des Mines, v. 259. t Poggendorff, Ann. xxxi. 142. 



