22 Dr Anderson's Analysis of 



of calcium and weighed. Another portion of the dry powder was then 

 dissolved in hydrochloric acid, and evaporated to drj'ness for the separa- 

 tion of the silicic acid. The drj- mass was then moistened with hydro- 

 chloric acid, digested for several hours, and dissolved in water, and the 

 silicic acid filtered off. The purity of the silicic acid was then tested by 

 solution in a boiling solution of carbonate of soda ; the undissolved mat- 

 ter, which consisted chieflj' of silicate of lime, reproduced by the strong 

 drying necessary for the sei^aration of the silicic acid, was then heated to 

 redness with carbonate of soda ; and alumina and lime were precipitated 

 respectively by ammonia and oxalate ammonia. The precipitates thus 

 obtained, weighed and subtracted from the first weight, gave that of the 

 pure silicic acid. The solution, after the filtration of the silicic acid, was 

 precipitated by caustic ammonia ; the precipitate, after being filtered, 

 washed, dried, and weighed, was dissolved in hydrochloric acid, and the 

 silicic acid left undissolved was weighed ; to the filtered solution potass 

 was added in sufficient quantity to redissolve the alumina at first preci- 

 pitated. By this means iron and magnesia were left undissolved, which 

 were again precipitated from a solution in hydrochloric acid, the first by 

 succinate, and the second by phosphate, of soda. The weights of -the 

 silicic acid, peroxide of iron, and magnesia, contained in the phosphate, 

 being subtracted from the first weight of the ammoniacal precipitate, 

 gave that of the pure alumina. The solution filtered from the ammonia- 

 cal precipitate was then treated with a solution of oxalate of ammonia ; 

 and the precipitate of oxalate of lime, after filtration and washing, was 

 heated to strong redness, and treated several times in succession with a 

 solution of carbonate of ammonia at a gentle heat as long as it continued 

 to gain weight ; and the lime was then weighed in the state of carbonate. 

 The solution which was left after the separation of the oxalate of lime, 

 was then evaporated to dryness in a counterpoised platinum crucible, 

 and the ammoniacal salts driven off by a moderate heat; after which a 

 higher temperature was given for the purpose of melting the remaining 

 salts. These, which consisted of chloride of potassium, chloride of so- 

 dium, and magnesia, were weighed together. By solution in water the 

 magnesia remained undissolved, and was filtered off, washed and weigh- 

 ed ; to the solution, chloride of platinum and spirit were added, when the 

 double chloride of platinum and potassium fell, which was collected on a 

 weighed filter, and from which the quantity of chloride of potassium, 

 and thence that of the potassa, were determined. By subtracti':^^n of the 

 weisrhts of magnesia and chloride of potassium from the first weight, 

 that of the chloride of sodium was obtained from which the soda was 

 reckoned. 



Caporcianite. 

 This mineral was kindly presented to me for analysis by Professor 

 Berzelius. It was first observed by Dr Paolo Savi at Caporciani, in the 

 valley of the Ceecino, where it occurs in a copper mine worked by two 



