ALCOHOL. 65 



this in the cone of sunlight produced by a lens. 

 Examine tyrosine and leucine as directed under those 

 articles. 



11. Add to coagulated albumen some concentrated 

 hydrochloric acid, and heat or allow to stand for some 

 time. The albumen will dissolve and form a blue or 

 violet solution, which, before the spectroscope, shows 

 an absorption band in yellow and green. 



12. To coagulated albumen add concentrated nitric 

 acid ; it will slowly dissolve, forming a yellow solution. 

 To this add a small quantity of mercurous nitrite and 

 boil, when a crimson precipitate will form. 



Alcohol, C 2 H 6 0. 1. In order to obtain alcohol from 

 organic tissues, or fluids which may contain it, heat, 

 coagulate, and distil them or their cold prepared watery 

 extracts from a copper or tin retort. To urine add 

 some tannic acid before distillation. The distillate 

 obtained is to be made alkaline with caustic potash, and 

 again distilled. Observe, if desirable, volatile acids in 

 residue in retort. The distillate is now acidified with 

 sulphuric acid, to fix volatile alkali, and again distilled, 

 This third distillate contains all the alcohol, but no 

 volatile acids or alkalies. 



2. Produce a test solution by dissolving one part of 

 dichromate of potassium in three hundred parts of 

 sulphuric acid. 



3. Mix a portion of the distillate with twice its 

 volume of concentrated sulphuric acid. Pour a small 

 quantity of this mixture into a quantity of test solu- 

 tion, and perceive that where the one fluid touches the 



5 



