formed ly the Action of the Nitric Acid. 1 93 



posited. This sediment, not so white as the first calcareous 

 salt, and in coarser powder, was dissolved with great effer- 

 vescence in the nitric acid. Its solution, which was of a 

 sharp pungent taste, was not precipitated by ammonia itself, 

 but very abundantly by the oxalate of ammonia. 



The liquor which floated above this carbonate of lime, 

 and which contained an excess of carbonate of potash, was 

 supersaturated by the acetic acid and evaporated to dryness; 

 the residue was treated by alcohol, in order to separate the 

 acetate of potash from the oxalate of the same base which 

 is not soluble in this liquid. The mixture when heated for 

 a few moments was thrown on a filter, where the oxalate of 

 lime remained, whereas the alkaline acetate passed through 

 with the alcohol. 



The portion insoluble in this liquid was dissolved in di- 

 stilled water : a drop of this solution mixed with half a 

 spoonful of lime water, formed in it a. pulverulent precipitate, 

 evidently oxalate of lime; and the same solution furnished 

 by evaporation crystals of oxalate of potash. 



The experiments which I have described, cannot leave 

 any doubt as to the nature of the calcareous salt, the pre- 

 sence of which alters the purity of the mucous acid ob- 

 tained from gum tragacanth. 



The same experiments repeated on gum arabic, and on 

 that which is known in commerce by the name of gum of 

 Bassorah, which is insoluble in water, furnished me with 

 nearly the same results. 



I observed, that in proportion as the mucous acid lost by 

 the nitric acid the oxalate of lime which rendered it impure, 

 it assumed a more flaky appearance. 



Scheelej to whom we owe the^discovery, at first called it 

 saccho- lactic acid, because he obtained it by treating the 

 sugar of milk with nitric acid. This denomination ceased 

 to be convenient, the moment it was proved that it might 

 be procured from the gums by a similar process ; and this 

 induced M. Fourcroy to substitute the appellation of mu- 

 cous acid for that of saccho-lactic acid. 



But is the mucous acid furnished by the sugar of milk 

 perfectly similar to that which we obtain from the gums ? 

 rs it altered like the latter by containing a remarkable 

 quantity of oxalate of lime; or rather does it contain but 

 the smallest quantity of this calcareous salt; or, finally, is it 

 totally deprived of it ? It appeared to me to be interesting 

 to find out a solution for these questions, and I set about 

 applying the process just described to the mucous acid fur- 

 nished by the sugar of milk. 



Vol. 36. No. T49. Sept. 1810. N I took 



