40§ Intelligetice and Miscellaneous Articles, 



▼iVons of Algiers, and it accompanies an ore of manganese -which is 

 now worked. It consists of two distinct portions, one lamellated 

 in three directions and of a rose colour ; the other, on the surface 

 exposed to the air, is black and earthy, and about one-third of an 

 inch thick ; it is, however, easy to ascertain the junction of these 

 two substances; it is very evident that the black portion is the 

 rose-coloured mineral altered. 



Red Mineral. — The density of this is 3'559 ; it scratches glass ; its 

 texture is sometimes laminated and sometimes granular ; it fuses 

 before the blowpipe, but not very readily ; it does not efFen'Csce 

 with acid ; boiling hydrochloric acid acts slowly and with difficulty 

 upon it, and deposits silica ; the solution was found to contain pro- 

 toxide of iron and of manganese, with lime and magnesia. 



In order to analyse this substance, a portion of it was fused with 

 carbonate of soda ; the fused mass was treated with hydrochloric 

 acid, and the silica separated by the usual process ; this was entirely 

 dissolved, after being weighed, in solution of potash ; the iron and 

 manganese were precipitated together from the solution by means of 

 hydrosulphate of ammonia ; the sulphurets were dissolved in con- 

 centrated hydrochloric acid, to which was added a small quantity of 

 nitric acid to peroxidize the iron ; the peroxide of iron was then se- 

 parated from the oxide of manganese by succinate of ammonia. 



The liquor from which the iron and manganese were separated 

 was saturated with an acid, boiled and filtered to separate the sul- 

 phur, then saturated with ammonia, and precipitated successively by 

 oxalate and phosphate of ammonia ; the lime was estimated in the 

 state of sulphate. The results of the ansJyses were as follows : — 



;,,.;,^ Silica ;.... 45-49 /. „ 



"r; Protoxide of manganese. 39-46'"^^°^?; 



;Zn Protoxide of iron ., .,^.,. 6-42 ' ^"'^^ 



^IL Lime .?t*^^ 4-66.d„Io8flI 



^lii Magnesia :'r.-^^?!^f^'?./ 2-60 



flortifH^^- ' - '/;: ,.: , ' ^ 9a 63 



j/;i(^his rose-coloured substance is therefore bisilicate of manganese 

 -(rhodonite of Beudant), as indicated by its external characters. A 

 very considerable portion of protoxide of manganese is replaced by 

 isomorphous bases; the formula of this mineral is (Mn . Fe . Ca Mg .) 



Black Substance on the Surface of the Silicate. — This substance is 

 friable ; heated in a tube it yields water. Hydrochloric acid attacks 

 it readily, with disengagement of chlorine, and leaves a rose -red re- 

 sidue. 



To analyse this substance, it was acted upon by hydrochloric acid, 

 and the chlorine evolved was received in a very clear solution of sul- 

 phurous acid mixed with chloride of barium ; the boiling was dis- 

 continued soonafter the decoloration of the substance, and the com- 

 ,plete expulsion of tlie chlorine. from the receiver, in order that the 

 red matter should be at; little acted upon as possible. The solution 

 of sulphurous acid boiled and filtered yielded sulphate of barytes. 



