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Some Contributions to the Chemistry of Mucoid. 



By Clarence E. May. 



In Physiological Chemistry, one meets with a proteid that has been 

 receiving more or less attention for several years past. This proteid is 

 classed among the glyco-albumins and occurs especially in ligaments and 

 tendons. Heretofore, the main problem connected with the chemistry of 

 this substance or group of very closely related substances, as the case may 

 be, has been the quantitative separation of the mucoid from mixtures of 

 albumin such as blood and egg albumin, and mucoid. The usual metbod 

 of separation has been to boil the neutral solution of true albumin and 

 mucoid, thereby coagulating the blood or egg albumin and leaving the mu- 

 coid in the filtrate. By acidifying the filtrate, it yielded the mucoid as a 

 flocculent precipitate which could be filtered and then weighed. 



The purpose of this work was to ascertain first, whether mucoid was 

 completely precipitated by the addition of a slight excess of dilute acid 

 to the mucoid solution (the solvent being half-saturated lime water). 

 Secondly, we wished to find out whether albumins were precipitated from 

 a mixture of albumin and mucoid, by acidifying the mixture in the cold. 

 Thirdly, we wished to ascertain whether mucoid coagulated by being boiled 

 in a neutral solution in the presence of neutral salts. And lastly, we wished 

 to see whether the various precipitations of the mucoid sample showed any 

 differences in nitrogen content ; in other words we desired to examine the 

 homogeneity of the various acid precipitates. 



The mucoid used was from several beef tendons (Achilles), and was 

 prepared by removing all water-soluble proteids by careful washing of the 

 tendons in tap water. The tendons were then cut into thin slices trans- 

 versly and again thoroughly washed with cold water. The next treatment 

 was to allow the slices of tendon to extract with half-saturated HSie water 

 for a day. This extract was filtered and made slightly acid with .2 per 

 cent, hydrochloric acid, using litmus paper as indicator. The solution, 

 with a casein-like precipitate was allowed to stand a short time when the 

 precipitate flocked together and settled to the bottom of the container, leav- 

 ing a perfectly clear supernatant liquid. 



