CARTILAGE. 385 



In the cartilage its potassium and sodium salts occur both as such 

 and in combination with collagen and albumins. A mixture of these 

 compounds, according to Schmiedeberg, constitutes the so-called 

 ehondromucoid of Morner. If a solution of gelatin is mixed with 

 an acidified solution of the potassium or sodium salts of the acid, 

 a precipitate occurs. This also results if cartilage is boiled with 

 water and the resulting impure solution of gelatin, which was 

 formerly termed ohondrin, is acidified with a dilute mineral acid. 

 The precipitate consists of the free chondroitin-sulphuric acid, and 

 is soluble in an excess of the acid. 



Chondroitin-sulphuric acid, while essentially a constituent of car- 

 tilage, has also been found in other organs of the body, as in the 

 inner coats of the larger arteries, in the kidneys, and under patho- 

 logical conditions in amyloid livers. Traces are likewise found in 

 the urine. 



Isolation. To isolate chondroitin-sulphuric acid from cartilage 

 shavings, the material is boiled with a 5 per cent, solution of caustic 

 alkali. The solution is neutralized, and freed by filtration from 

 the alkaline albuminates which have been formed during the process 

 of boiling. Albumoses are removed by means of tannic acid, the 

 excess 'of the latter by means of lead subacetate, and the excess 

 of lead with hydrogen sulphide. The acid is then precipitated with 

 alcohol. To purify the substance, it is dissolved in water, and the 

 solution dialyzed and reprecipitated with alcohol. The solution in 

 water and precipitation with alcohol is repeated several times, when 

 the acid is finally washed with alcoholic ether. 



Isolation of Chondromucoid. To isolate the ehondromucoid, 

 viz., the compounds of chondroitin-sulphuric acid with collagen 

 and albumins, the cartilage shavings are first extracted with water, 

 which dissolves the free chondroitin-sulphuric acid and a small 

 amount of the ehondromucoid. On acidulating this solution with 

 a 3 pro mille solution of hydrochloric acid and heating on a water- 

 batli, the ehondromucoid is gradually precipitated, while the free 

 acid remains in solution. The cartilaginous residue is then ex- 

 tracted with a 2 to 3 pro mille solution of hydrochloric acid at a 

 temperature of 35 to 40 C., which dissolves any collagen that 

 may be present as such. After washing with water the remaining 

 material is extracted with a 5 pro mille solution of caustic alkali. 

 The chondromuooid is thus dissolved, and is then precipitated with 

 an acid. After repeated solution in an alkali and precipitation 

 with an acid it is finally washed with alcohol and ether. 



Albumoid. The albumoid which is found in the cartilage of 

 adult animals is apparently closely related to elastin and keratin, but 

 differs from the latter in containing sulphur, and from the former in 

 its digestibility by gastric juice. It gives the common color-reac- 

 tions of the albumins, but is insoluble in all neutral solvents, and 

 dissolves in acids and alkalies only with great difficulty. 



Isolation. To isolate the substance, cartilage shavings are first 



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