Ig COMPARATIVE EXAMINATION OP MUCOUS ACIl>. 



A second portion of weak nitric acid, left to stand on the 

 residuum the same length of time, yielded a fresh quantity 

 of oxalate of lime on the addition of ammonia. 



It required eight portions of diluted nitric acid in suc- 

 cession, completely to free this mucous acid from oxalate of 

 lime. The quantity was each time less however, and the 

 ninth portion showed scarcely any perceptible indication 

 of it. 



The eight precipitates together amounted to 2*5 gram, 

 [38-6 grs.] 

 This proved It was of importance to ascertain, whether this foreign 



tionyfthesdt. "»^tter, which had the appearance of oxalate of lime, were 

 in reality this salt. J therefore boiled it with a solution of 

 saturated carbonate of potash, and when the mutual de- 

 composition of the two salts appeared to me complete, I 

 collected on a tilterthe portion that had precipitated. This 

 precipitate, not so white as the former calcareous salt, and 

 in coarser powder, dissolved with great effervescence in ni- 

 tric acid. Its solution, which was acrid to the taste, was 

 not precipitated by ammonia, but very copiously by oxalate 

 of ammonia. 



The supernatant liquid, which contained an excess of 

 carbonate of potash, was supersaturated by acetic acid, 

 ^ evaporated to dryness, and the residuum treated with alco- 



hol, in order to separate the acetate from the oxalate of 

 potash, which is not soluble in this menstruum. The mix- 

 ture, beino- heated a few moments, was filtered, when the 

 acetate of potash passed through with the alcohol, and the 

 oxalate remained behind. 



The matter insoluble in alcohol was dissolved in distilled 

 water; and a drop of this solution, added to half a spoonful 

 of lime water, threw down a pulverulent precipitate, evi- 

 dently of oxalate of lime. The same solution yielded by 

 evaporation crystals of oxalate of potash. 



The experiments I have described leave no doubt of the 



nature of the calcareous salt, that utiects the purity of the 



mucous acid obtained from gum tragacanth. 



Othergums The same experiments repeated on gum arabic^ and on 



similar. ^\^q^ called in the shops gum of Bassorah, which does not 



dissolve in water, afforded me nearly the same Fesults. 



I observed. 



