1820.] M. Stromeyer on Polyhalite. 435 



b. The powder hence remaining, after being dried in a heat of 

 the temperature of boiling water, was found to weigh 2-275 grm. 

 First of all water, and afterwards nitric acid, being gradually- 

 poured on it, it was dissolved without any application of heat, 

 creating a continual effervescence, and producing a solution 

 limpid and colourless like water, nothing being left undissolved, 

 except a very little red oxide of iron weighing only 0'014 grm. 



c. In order to ascertain whether this nitric solution contained 

 any portion of the fossil not yet decomposed, or whether any 

 oxide of iron had been taken up by the nitric acid along with the 

 lime and carbonate of magnesia, I evaporated it until perfectly 

 dry. But during this operation, the solution deposited only some 

 crystals of gypsum, scarcely amounting to 0*01 grm. ; and 

 when dried underwent no change of colour which might prove 

 the presence of iron, but exhibited a completely white saline 

 mass which was taken up by water without leaving any residuum. 

 Upon carefully pouring some caustic ammonia with a few drops 

 of nitric acid into the solution, the latter was hardly disturbed, 

 and deposited only single red flakes of the hydrate of oxidated 

 iron, the whole of which, when separated by filtration and well 

 dried, weighed only 0"005 grm. ; thus merely 0*004 grm. of red 

 oxide of iron were indicated by the process. 



d. The nitric solution being afterwards condensed by evapo- 

 ration and put into a crucible of platina, was mixed with a suffi- 

 cient quantity of sulphuric acid, and being continually stirred up 

 during the whole time was very gradually dried by a moderate 

 heat. The saline body, after being well exsiccated, was sub- 

 mitted to the fire until all the sulphuric acid was dispelled along 

 with the nitric acid which had been left. Then the ignited mass, 

 weighing 3" 179 grm. being washed as usual, was separated into 

 2-241 grm. of anhydrous sulphate of hme, and 0-938 grm. of sul- 

 phate of magnesia equally freed from water. 



e. The alkaline liquor obtained by experiment a was rendered 

 rather thick in consequence of ebullition, and deposited a white 

 powder, which, being separated by filtration, edulcorated, and well 

 dried, weighed 0-05 grm. and in quality resembled carbonate of 

 magnesia. According to Berzelius, these 0-05 grm. of carbonate 

 of magnesia are equal to 0-064 grm. of ignited sulphate of 

 magnesia. 



f. From this liquor the sulphuric acid was afterwards precipi- 

 tated by the assistance of muriate of barytes and the addition of 

 muriatic acid sufficient to produce an acid reaction ; from which 

 were obtained 7-882 grm. of sulphate of barytes exsiccated in a 

 temperature equalling that of boiling water, which were after- 

 wards reduced by ignition to 7-650 grm. 



But as sulphate of barytes contains in 100 parts 34 of sulphu- 

 ric acid there are 2-601 grm. of this acid in 7-650 of sulphate of 

 barytes ; to which are to be added 0*0046 of sulphuric acid 

 retained with the lime b j so that the entire quantity of sulphuric 



2e2 



