COMPOUND CARBONATE OF LIM£. 151 



lour of iron spar. Tt is sometimes perfectly transparent: 

 but most commonly it has a slight yellowish tint, becomes 

 opake, and is covered with a brown oxide, as it is decom- 

 posed in the damp parts of the mine. 



Before the blowpipe it becomes black, and is slightly al- 

 tered. It scarcely effervesces with acids, unless previously 

 powdered. 



Having powdered Pnd sifted it, I took 5 grammes [77 Analysed. 

 grains], on which I poured strong nitric acid. On applying /^f^^"^^^" 

 a gentle heat, the effervescence immediately became very 

 brisk ; nitrous gas was evolved ; and the powder assumed a 

 brov/n colour. Having evaporated to dryness, I poured on 

 fresh acid, and repeated the same operation. 



I next dissolved the whole in muriatic acid, evaporated With muriatic, 

 gently to expel the excess of acid, and then dissolved in wa- ? pi^ecipitated 

 %r,i , . , . 1 /• 1- 1 1, • °y prussiaie of 



ter. Tne solution, which was ot a light yellow, was preci- potash> 



pitated by prussiate of potash. The result was a deep blue 

 prussiate, which was filtered and washed. 



The solution, completely neutralized, was precipitated and by oxalate 

 by oxalate of ammonia, and yielded oxalate of lime, which, ^^ ^"in^oaia. 

 when washed and dried, weighed 3*95 grammes. 



Caustic potash threw down from the liquor a copious Caustic potash 

 white flocculent precipitate, which, when washed, dried, ^^'^^ ^o"''* 

 and calcined in a red heat, weighed 0*5 of a gr. This sub- 

 stance, which was of a fine white colour, dissolved entirely 

 in sulphuric acid, and yielded a bitter salt. Carbonate 

 of ammonia did not precipitate it ; therefore it was magne- 

 £ta. 



The prussiates when dried were strongly calcined, and Iron oxided, 

 the residuum oxided to a maximum by nitric acid. 



The oxides were redissolved in muriatic acid ; evaporated dissolved in 



gently to neutralize them ; and then diluted with a large "^""^^^^ ^^^^» 



quantity of water. No residuum was left. 



This solution was precipitated by carbonate of potash, sa- pi'ec^pitated by 

 , , « 1 m 1 potash, 



turated, and afterward filtered. 



The carbonate deposited on the filter was redissolved in redissoWed and 

 muriatic acid, precipitated afresh by carbonate of potash, P""^"!?"*^®"* 

 saturated, and filtered. 



The two filtered liquors being mixed together, they were Liquors evapo- 

 iubjected to evaporation for about two hours, when they "^ 



deposilied 



