COHPABATITE EXAMINATION OF MCrODS ACID. 



15 



To solve these questions I undertook the following expe- pxperimenta 



riments. to find this. 



I dij^ested 60 gram. [926*4 grs.] of gum tragacanth in Gum trjca- 



vioht tiiues their weight of pure nitric acid at 36^ fsp, gray, c*^"^*^/;'^"- 

 T 1 1 1 -v .,, . 1 1 . veried into 



l'333J; heated the mixture, till it was reduced to the mucou« acid. 



consistence of honey ; and then added asuHicient quantity 



of water. 



This would not dissolve a white, pulverulent substance,^ 

 which, collected on a filter and dried in the open ^ir, 

 weighed 9*5 gram. [l46*7 gi's]. This was mucous acid. 

 The liquid containing the soluble portion of the mixture 

 was of a yellow colour. 1 evaporated it, till the Hioment 

 1 perceived a slight pellicle form on its snrfiice, when I 

 removed it from the fire. As it cooled, it deposited a great 

 quantity of crystals, some in laminte, others in needles 

 easily perceived to be oxalic acid. To separate this acid Oxalic acul 

 from the mucous, I poured on the mixture alcohol at 40° *^***^'^'"^/ 

 [sp. grav. 0*817], which dissolved the oxalic acid, without 

 acting on the mucous. This, collected on a filter, weighed 

 i2*l ^vnm* [3^1*4 grs]. The alcoholic solution, being gently 

 evaporated, yielded a coloured mass, which I dissoh'ed in 

 water to obtain whiter and purer crystals. 



The mother waters of this second portion of mucous and malic, 

 acid and of oxalic acid contained a mixture of oxalic and 

 malic acids, which I separated by means I shall not men- 

 tion, as they are foreign to my subject. 



The first portion of mucous acid I obtained was very The mucous 

 white. When dried it had the clotted appearance of^^' 

 starch. This I emj)loyed in ray experiments, rejecting 

 the second portion, which did not appear to me so pure. 



To find whether there were any oxalate of lifne in thjs contarned 



mucous acjd, I mixed one part of the nitric acid above- J^''^'^^^ ^'^ 



. lime, 



mentioned with ten of distilled water, and poured it on 



the mucous acid, 1 then exposed the whole to a heat of 40* 

 or 50^ [104° 61- 122° F.] for 43 hours, shaking it occasionally, 

 to promote the action of the menstruum. The superna- 

 tant liquor being poured off, ammonia immediat'.'ly threw 

 down from it a white earthy salt in si^ky filaments, which 

 had all the physical properties of oxalate of lime* 



A second 



