Jg COMPARATiVfi EXAMINATION OF MUCOUS AGIO. 



let, There is a striking difference between the mucous 

 acid obtained Uy the action of the nitric acid from gums, 

 and from the sugar of milk. 



^dly. This diffeixence conaists in the former bein^ always 

 contaminated witliu mixture of oxalate of lime, proportional 

 to the lime contained in the <r«ini ; wiiile the mucous acid 

 from sugar of milk does not exhibit the least trace of this 

 calcareous salt, and seems to be perfectly pure. 



3dly, The mucous acid from gum may be brought to a 

 similar state of purity by a very simple process, whicji cm}- 

 sists, 1st, in removing all the oxalate of lime by repeated 

 digestions in very dilute nitric acid ; and, 2dly, in boiling it 

 in water, which dissolves it, without di^vJlving the floccu- 

 Icnt matter, that the nitric acid did not take up. . ^ 



4thly, The mucous acid from gum,Mhcn thus freed frf>n[l 

 substances foreign to its nature, is exactly similar to that 

 from sugar of milk, possesses all the properties that cha- 

 V^tCterise this acid, atid may be employed with equal ad- 

 vantage in the most delicate experiments, or such as require 

 this acid to be of the utmost puiity. 

 Mucous acid Since I wrote the above I have ascertained, that undeF 



fiomgumcon- ^p^^^;,, circumstances the mucous acid obtained from cum 



tams mucite , . . . 



of lime, when is mixed with mucite of lime, instead of the oxalate I have 



prepared with mentioned. , This happens, when the nitric acid employed 

 diluted nrtric . . ,,,•,,• i j 



acW. IS not in a concentrated state, but diluted with water, and 



the process consequently goes on not rapidly, but slowly. 



The difference of the results is easily understood. 



R 'Jason of jf ^^ weak acid be employed, the mucous acid is at first 



produced alone; it precil)itates with the lime, with which 



it forms a salt of little solubility ; and it may be separated 



from the mixture previous to the formation of the oxalic 



acid, which requires the concentration of the nitric. If on 



the contrary concentrated nitric acid be used, the formation 



of the two acidsj though taking place in succession, is very 



near in point of time; and it may readily be supposed, that 



in this case the oxalic acid, in proportion as it is formed, 



lays hold of the lime in consequence'of its great affinity for 



tliAS earth. _ ,^. 



I shall ad(J[:one in^re fact, that has led mc to remark a 



singular property of the mucous acid, which 1. purpose to 



examine more ful4y. When 



