FIBROUS CONNECTIVE TISSUE. 45 



subside, this operation being repeated with fresh quantities of 

 acid until the latter failed to give any proteid reaction. In 

 this manner it was hoped to remove all adherent albuminous 

 matter extracted from the tissue by the lime-water. The two 

 portions of mucin were then united and washed by decantation 

 with distilled water until the acid was entirely removed. As 

 the fluid became less and less acid, more tune was required for 

 the precipitate to settle, as the latter tended to swell in the wa- 

 ter and was more inclined to float on the surface of the fluid. 



The mucin was next dissolved in half-saturated lime-water, 

 of which a large volume was required, the solution filtered 

 through paper, and the mucin reprecipitated by the addition 

 of an excess of 0.2 per cent hydrochloric acid, a small quantity 

 of stronger hydrochloric acid being likewise added to induce a 

 good flocculent separation of the substance. The precipitate 

 was again washed by decantation with 0.2 per cent hydrochloric 

 acid, and lastly with water, until the acid was entirely removed. 

 Whenever it was necessary for the precipitate to stand for 

 some time with water, the mixture was kept as cool as possible, 

 and a little alcoholic solution of thymol added to guard against 

 putrefactive changes. When the acid was wholly removed 

 from the precipitate the water was replaced by weak alcohol, 

 and finally by 95 per cent alcohol, repeatedly renewed, 

 until the substance was thoroughly dehydrated, after which 

 the precipitate was collected on a filter and allowed to drain. 

 It was then boiled with alcohol-ether (a mixture of equal 

 parts absolute alcohol and ether) in a suitable flask connected 

 with an inverted Liebig's condenser for many days i. e., with 

 renewed quantities of alcohol-ether until the latter gave no 

 residue on evaporation. As Loebisch has shown, this is quite 

 an important part of the process of purification, since a certain 

 amount of foreign extractive matter adheres tenaciously to 

 the mucin, and can be removed only by long-continued extrac- 

 tion with the above mixture. When this process was completed 

 the mucin was thrown upon a filter, washed thoroughly with 

 ether, and finally dried over sulphuric acid. When quite dry 

 it presented the appearance of a perfectly white powder, light 



