1821.] Dr. Bonsdorffon Tabular Spar from Pargas. 301 



been separated, as much as possible, by mechanical means, I 

 endeavoured to dissolve the remaining portions of calcareous 

 spar by acetic acid ; but I found that this mineral possessed the 

 unusual property of being to a considerable extent decomposed 

 by acetic acid. I had, therefore, no other method of separating 

 the calcareous spar, than that of treating the levigated mineral 

 with an aqueous solution of carbonic acid, and this answered the 

 purpose extremely well. 



1 now proceeded with the analysis as follows: 175*5* parts of 

 the purified powder of tabular spar were mixed with three times 

 their weight of carbonate of potash, and heated in a platina cru- 

 cible ; the mass treated with muriatic acid, the solution evapo- 

 rated to dryness, and the residuum again treated with muriatic 

 acid, left the silica, which, when washed, dried, and ignited, 

 weighed 93-2 parts. The muriatic solution saturated with 

 ammonia afforded a small quantity of precipitate, which, when 

 boiled with solution of potash, exhibited only a trace of alumina* 

 the portion insoluble in potash consisted entirely of peroxide of 

 iron, which weighed, after ignition, 2-3 parts = 20 of protoxide 

 of iron. 



Carbonate of ammonia added to the solution from which the 

 alumina and oxide of iron had been separated by ammonia, gave 

 a white precipitate, which was carbonate of lime ; it weighed 

 138 parts = 77-8 of lime. This carbonate of lime was dissolved 

 in a mixture of muriatic and sulphuric acid, and evaporated to 

 dryness. The ignited sulphate of lime weighed 185*4 parts = 

 77 of lime ; there is, consequently, a little difference in the weight 

 of the lime as deduced from the carbonate and the sulphate. I 

 shall, therefore, take the mean = 77*4 as the true quantity of 

 lime : a little water was added to the sulphate of lime, and the 

 solution obtained being examined, was not found to contain any 

 magnesia. 



Ihe solution which remained after precipitation with carbonate 

 of ammonia was heated to ebullition, and solution of carbonate 

 of potash added to it. This gave a precipitate which, when 

 washed and ignited, weighed 2*6 parts. This treated with sul- 

 phuric acid evaporated to dryness, and treated with a small 

 quantity of water, left 3*3 of" sulphate of lime = 1*4 of lime, 

 which, deducted from 2*6, leave 1*2 as the quantity of magnesia 

 contained in the mineral. 



In order to determine the quantity of volatile matter contained 

 in this mineral, a portion of it that had been purified, and which 

 weighed 50*5 parts, was ignited for an hour in a platina crucible; 

 it then weighed 50*0, again exposed to heat increased by the 

 bellows, it suffered no further diminution of weight. According 

 to this experiment, the loss by heat amounts to 0*99 per cent. 



• The quantity actually employed was 1755 gramme. 



