lQi Comparative Examination of the Mucous Acid 



I took, in consequence, one part of sugar of milk, which 

 I boiled with eight parts of nitric acid of the same strength 

 with the foregoing. I separated by decantation the first 

 portions of mucous acid which were formed, and I added 

 to the residue a new quantity of nitric acid. A second 

 portion of mucous acid was deposited, which when united 

 with the first gave a total weight of twelve grammes, or the 

 fifth part of the sugar of milk submitted to the experiment. 



I remarked that, after washing, this mucous acid, di- 

 luted in water, had an appearance equally flaky with that of 

 the gum when it was deprived of its oxalate of lime by 

 the weak acid. This remark inclined me to think that 

 this acid was much purer than that of the gum, and this 

 opinion was confirmed by the nitric acid having had no 

 action on it. It did not take up from it the smallest quan- 

 tity of oxalate of lime, after a long continued digestion, for 

 the ammonia did not take the slightest effect on the super- 

 natant liquor. 



In addition to this, what leaves no doubt as to the per- 

 fect purity of the mucous acid of the sugar of milk, is, the 

 circumstance of its easily and entirely dissolving in boiling 

 water. This entire solubility in boiling water proves that 

 it enjoys a greater purity than the mucous acid of gum, 

 even when the latter has been purified by the means above 

 mentioned: in fact, the Tatter, well freed from oxalate of 

 lime, still leaves, when it is boiled with distilled water, an 

 insoluble flaky matter forming the 0*06 of its weight, 

 which dries into a gray horny semitransparent body, similar 

 in appearance to the mucous substance which connects the 

 molecules of animal concretions, although on burning 

 coals it does not furnish the ammoniacal and fetid smell 

 of animal compounds, and which furnishes on calcination 

 carbonate of lime. The too small quantity which I ob- 

 tained of it did not admit of my making experiments which 

 would have thrown more light on the nature of this body. 



From the facts detailed in this memoir, we may draw 

 the following consequences : 



1. There exists a very remarkable difference between the 

 mucous acid procured from gums, and that which we ob- 

 tain from the sugar of milk by the action of the nitric acid. 



2. This difference consists in ahe first being constantly 

 altered by the mixture of a quantity of oxalate of lime in 

 proportion to that of the earth which the gums contain, 

 whereas the mucous acid of the sugar of milk does not 

 offer the slightest trace of this calcareous salt, and seems 

 perfectly pure. 



3. We 



