ELASTIC TISSUE. 113 



trine with dilute sulphuric acid, it will be converted into 

 glyJcose. 



Elastic Tissue. 1. From the neck-band and middle 

 coat of arteries and veins. Remove extraneous 

 matters by boiling with alcohol, ether, water, strong 

 acetic acid, dilute potash, water, dilute hydrochloric 

 acid (10%), and again with water and dry at 100 C. 

 The residue, elastine, is a brittle, yellowish, fibrous, 

 mass, swelling up, but insoluble in water, insoluble in 

 alcohol, ether, and acetic acid. Examine as follows : 



2. Soak in dilute acetic acid; it will recover its 

 elasticity and fibrous appearance. 



3. Boil a long time with water; it will remain in- 

 soluble and will not be converted into gelatine. (See 

 Connective Tissue.) 



4. Digest with strong caustic potash ; a brown 

 solution will be formed. Neutralise with sulphuric 

 acid and add tannic acid, a precipitate will ensue. No 

 other acid will produce a precipitate, and the solution 

 will not form a jelly when evaporated. 



5. Chemolyse by boiling with dilute sulphuric acid ; 

 it will yield nearly the same products as albumen (q. v.). 



6. Heat on platinum foil ; it will burn away entirely 

 without ash. 



7. Fuse with caustic potash, dissolve in water, and 

 add potash-acetate of lead. No black precipitate will 

 form, proving absence of sulphur. 



Excretine. C 78 H 156 S0 2 (Marcet). 1. Extract dried 

 human fasces with boiling absolute alcohol, on evapo- 



8 



