K. Ml YAK I-:. 
388 
another twenty-four hours. The mucic acid has in the meantime crystallized, 
but it is mixed with considerable material only partially oxidized by the 
nitric acid. Filter the solution therefore through filter paper, wash with 
30 cc. of water to remove as much of the nitric acid as possible, and replace 
the filter and contents in the beaker. Add 30 cc. of ammonium carbonate 
solution, consisting of 1 part ammonium carbonate, 19 parts water, and 1 
part strong ammonium hydroxid, and heat the mixture on a water bath, at 
80 °C., for fifteen minutes, with constant stirring. The ammonium carbonate 
takes up the mucic acid, forming the soluble mucate of ammonia. Then wash 
the filter paper and contents several times with hot water by decantation, 
passing the washings through a filter paper, to which finally transfer the 
material and thoroughly wash. Evaporate the filtrate to dryness over a 
water bath, avoiding unnecessary heating which causes decomposition, add 
5 cc. of nitric acid of 1.15 specific gravity, thoroughly stir the mixture and 
allow to stand for thirty minutes. The nitric acid decomposes the ammonium 
mucate, precipitating the mucic acid; collect this on a tared filter or gooeh, 
wash with from 10 to 15 cc. of water, then with GO cc. of alcohol, and a 
number of times with ether, dry at the temperature of boiling, wafer for 
three hours, and weigh. Multiply mucic acid by 1.33 which gives galactose, 
and multiply this product by 0.9 which gives galactan ” 
The results obtained by the method above described are far from being 
accurate, at least in the case of natural products, according to the experiences 
in our laboratory. The chief reasons for the inaccuracy seem to us to be 
the following. 
1) The presence of partially decomposed organic material in the solution 
appears to hinder greatly the crystallization of the mucic acid formed by 
oxidation with nitric acid. The fact is well illustrated by the experimental 
results which follow. 
Table I. 
Sample. • Mucic acid obtained. 
O' 
Ö 
Natural stuff 0 alone (3 g) 0.1214 
1) Cotyledon of soy-bean. 
