446 CHEMISTRY OF THE TISSUES. 



tin in concentrated nitric acid, and let it stay some time. It 

 will swell up, then become yellow, and lastly form a mucilagi- 

 nous solution. Add ammonia, and it will become a deep 

 orange-red. 2. Millon's reaction. Test a piece of elastin with 

 Millon's reagent. It will become slightly red. 



Decomposition. On boiling elastin with concentrated sul- 

 phuric acid, it is decomposed and yields leucine, but no 

 tyrosine. 



** 49. Cartilage. Chondrogen. The intercellular sub- 

 stance of hyaline cartilage, and that which lies between the 

 fibres of fibrocartilage, consists mainly of chondrogen, so 

 named because it is dissolved by boiling in water and forms 

 chondrin. 



Hafnttility. Take a piece of costal cartilage of a sheep or ox 

 mid test its solubility in the following reagents : 1. Cold water. 

 It is insoluble. When allowed to dry before it is put in water, 

 it swells up slightly. 2. In boiling water, it dissolves. On 

 cooling, it forms a jelly. 3. In acetic acid it is insoluble. 

 When dry, it swells very little in acetic acid. 



50. Chondrin. /'/// /-(///OH Boil the costal cartilages or 

 trachea of a sheep or ox in water till the perichondrium strips 

 easily oil'. Hi-move the perichondrium. Cut up the cartilages 

 into very small pieces, and boil them with water for several 

 hours. If a Papin's digester is at hand, boil them in it under 

 a pressure of 2-o atmospheres. Filter while hot. The fil- 

 trate will be strongly opalescent. Put part of it into a beaker 

 and allow it to cool. It will form a jelly. To the remainder 

 of the filtrate add acetic acid, and the chondrin will be pre- 

 cipitated. 



Solubility. Test the solubility of chondrin, using either 

 that precipitated by acetic acid, or the jell}' which formed on 

 cooling, in the following reagents: 1. In cold water it is in- 

 soluble. Heat it, and it is dissolved. It is soluble in 2. Solu- 

 tions of alkaline salts, as sodium sulphate, and is easily solu- 

 ble in :>. Dilute mineral acids, L Liquor potassjv, and .">. Liquor 

 ammonia*. It is insoluble in ('. Alcohol, and 7. Ether. 



7V r//;//r///o/,. Add to a warm solution of chondrin in 

 water, f 1. Acetic acid. It will be precipitated, f 2. Add to 

 this ;i little sodium chloride or sulphate. The precipitate will 

 n-dixxolvu. ;*. Add sodium sulphate to a, watery solution of 

 elioinlrin. and afterwards acetic acid. No precipitate will fall. 

 4. Pilule hydrochloric or other mineral acid. The chondrin is 

 precipitated and is dissolved by excess of acid. 5. Alum pre- 

 cipitates chondrin ; excels dissolves it. G. Lead acetate, 7. Sil- 

 ver nitrj.te, s. Chlorine water, all precipitate chondrin. 



/;//V, / ,,/' llnilintj. Boil a watery solution of chondrin for a 

 long time. Let it cool, and it will be found to have lost its 



