a Mineral from Faroe. 49 



tion, it weighed 14.35 grains. It dissolved in boiling potash ley 

 except a residue of .47 of a grain, which shall be afterwards no- 

 ticed. There was thus left of silica 13.88 grains. 



d, The liquid separated from silica was treated with ammo- 

 nia in some excess. A few flocks only fell, becoming gradually 

 brown. These were separated by filtration, and, after ignition, 

 weighed .14 of a grain. 



e, These ignited flocks were digested in muriatic acid, and 

 were dissolved, except a residue of .02 of silica. The solution 

 was boiled with excess of caustic potash. The precipitate re- 

 maining undissolved was separated by filtration, and the liquid 

 supersaturated with muriatic acid, and treated with carbonate 

 of ammonia. A slight muddiness ensued ; but the quantity or 

 nature of the precipitate was not determined, from its small 

 amount. 



f, The residue left by the caustic potash in e, was dissolved 

 in muriatic acid, boiled with a little nitric acid, neutralized by 

 ammonia, and precipitated by benzoate of ammonia. The pre- 

 cipitate, ignited with a little nitric acid, yielded .04 of oxide of 

 iron. The residual liquid was boiled with carbonate of soda. A 

 white precipitate fell, which, after ignition, weighed .05. This, 

 when examined, proved to be oxide of manganese, mixed with 

 some lime ; but as the proportion of lime could not be determined, 

 the whole may be held as red oxide of manganese, equivalent to 

 .046 of protoxide, although, from the reaction of the mineral on 

 platinum foil with soda, formerly mentioned, the real quantity of 

 that oxide was apparently less. 



g, The liquid which had been precipitated by ammonia in d, 

 after concentration by heat, was brought nearly to the boiling 

 point, and carbonate of ammonia added. A plentiful white pre- 

 cipitate fell, which, after being collected by filtration, and duly 

 dried, weighed 1 1 .74 grains. This precipitate, which was carbo- 

 nate of lime, dissolved without residue in diluted muriatic acid. 

 A few drops of hydrosulphuret of ammonia were added to the 



VOL. XIII. PART I. G 



