HANDBOOK FOR BIO-CHEMICAL LABORATORY. 77 



HEYNSIUS'S Test (Albumin). Strongly acidify the solution 

 with acetic acid and add a few cubic centimetres of a satu- 

 rated solution of sodium chloride and boil. In the presence 

 of albumin a flocculent precipitate is produced. 



Test (Albumin). Add solid meta-phos- 

 phoric acid to the liquid to be tested, when a cloudiness or 

 precipitate is formed if albumin is present. 



HIPPURIC ACID. See Lilcke. 



HOFMANX'S Test (Ty rosin). Add a few drops Millon's 

 reagent to the solution to be tested and boil for a time. In 

 the presence of tyrosin the liquid becomes a beautiful red and 

 then yields a red precipitate. The test may also be applied 

 by first adding mercuric nitrate and boiling, and after this 

 adding nitric acid containing some nitrous acid. 



HOFMEISTER'S Test (Peptones). A solution entirely free 

 from albumin gives a precipitate with an acetic acid solution 

 of phospho-tungstic acid. The phospho-tungstic acid may 

 be prepared by dissolving commercial sodium tungstate in 

 hot water and adding phosphoric acid until acid in reaction. 

 This liquid is strongly acidified with hydrochloric acid after 

 cooling and filtered after 24 hours. 



HOFMEISTER'S Test (Leucin).0n warming a solution of 

 leucin with mercurous nitrate a deposit of metallic mercury is 

 formed, 



HOPPE SEYLER'sTest (Carbon Monoxide in Blood.) Treat 

 the blood with double its volume of caustic soda solution of 

 1.3 sp. gr. Ordinary blood is converted into a dingy brown- 

 ish mass, which when spread out on porcelain is brown, with 

 a shade of green. Carbon monoxide blood gives under the 

 same conditions a red mass, which if spread out on porcelain 

 shows a beautiful red color. 



