Description and Analysis of Pickeringite. 361 



boiling solution of caustic potash, were redissolved in hydrochlo- 

 ric acid ; the lime was combined with oxalic acid and separated. 

 A solution of chlorine in carbonate of soda removed manganese 

 and alumina, leaving only magnesia in solution. The small 

 quantity of magnesia was estimated as an ammonia phosphate. 



The solution containing an excess of bicarbonate of ammonia 

 was boiled, and thus rendered slightly acid. Nitrate of silver 

 removed the chlorine of the hydrochloric acid, as chloride of sil- 

 ver ; neither iodine or bromine could be detected. On rendering 

 the fluid acid, by hydrochloric acid, the silver was separated, and 

 hydrochlorate of baryta separated the sulphuric acid, as a pure 

 sulphate of baryta. By an excess of sulphuric acid and evapo- 

 ration, the baryta was precipitated, and the clear solution of sa- 

 line matter was slowly reduced to a dry mass. By heating with 

 the usual precautions, a light gray anhydrous sulphate of magne- 

 sia was obtained, from the weight of which, the weight of the 

 magnesia was calculated and added to that precipitated with the 

 alumina. By warm water, some flocks of ferruginous oxide of 

 manganese had been separated from the dry saline matter ; these 

 were added to those from the alumina, and all converted by heat 

 into the red oxide, from which the weights of protoxides were 

 calculated. For determining the quantity of water contained in 

 the mineral, a part of the fragments used in the above analysis, 

 and weighed from the same state of dryness in air at 84° F., was 

 chosen. Fifty parts contained in a tube retort, connected with a 

 vessel of ammoniacal solution, were heated slowly and uniformly. 

 The porous mass lost 22-625 parts, and the ammonia had received 

 0-26S of hydrochloric acid. On heating the mass till vapors of 

 sulphuric acid were disengaged, the loss was 23-310. The sul- 

 phuric acid weighed, in the state of sulphate of baryta, 0-287 

 parts, which, with 0-268 of hydrochloric acid, give *5S5 of acids, 

 which were deducted from the total loss of weight due to heat- 

 ing. This mineral generally contains phosphoric acid, which in 

 part replaces the sulphuric acid. It precipitates in union with the 

 alumina, and appears to be an accidental impregnation. I found 

 the most ready mode of detecting its presence in the alumina, to 

 be that of forming ammonia alum, by adding a great excess of 

 muriate of ammonia to a sulphuric solution while warm. On 

 cooling, not only alum, but crystals of muriate of ammonia should 

 form. By washing these crystals in a solution of muriate of am- 



Vol. xlvi, No. 2.— Jan.-March, 1844. 46 



