COLOBTNO MATTER. 



193 



Extraction of fruit colors with amyl-alcohol and with etfier. 



It will be seen from these two tables that auiyl-alcohol, as a rule, extracts 

 fruit-coloring matter from acid solution, while ether does not. Neither amyl- 

 alcohol nor ether extracted any color from alkaline solution of the fruit juice. 



4. Detection of Acid Magenta Girard's Methods 



Add to 100 cc of solution to be tested 2 cc of potassium hydroxid (5 to 100). 

 If this does not neutralize the acid, add enough to do it. Then add 4 cc of 

 mercuric acetate (10 to 100), agitate, and filter. The filtrate should be color- 

 less and slightly alkaline. Acidify with a slight excess of dilute sulphuric acid, 

 and if the solution remains uncolored there is no acid magenta present. If it 

 becomes a light violet-red and there has been no other dye shown by the amyl- 

 alcohol extracts, the presence of acid magenta is shown. 



Acid magenta in acid solution dyes wool a magenta red. Wool dyed with 

 it is turned yellow by strong hydrochloric acid, decolorized by ammonium 

 hydroxid and regains its color when washed with water. 



5. Test for Martius Yellow or Naphthalene Yellow. 



Extract with 95 per cent alcohol from an acidulated sample. Evaporate the 

 alcoholic solution to dryness with a piece of wool, which will be dyed a bright 

 yellow, and test the dyed wool. Both sulphuric and hydrochloric acids com- 

 pletely decolorize it. 



6. Beta's Method of Identification of Organic Coloring- Matter. & 



The coloring matters are divided into four groups by the use of stannous 

 chlorid and hydrochloric acid and of caustic potash. 



The reagents are a 10 per cent solution of stannous chlorid and a 20 per cent 

 solution of caustic potash. 



Dilute the aqueous or alcoholic solution of coloring matter to about 1 to 

 10,000. This strength is not of vital importance, but the color must not be too 

 deep, as it will mask the reduction in some cases, as with safranins, where it 

 is slow and not complete. Add to the solution a few drops of stannous chlorid 



Girard and Dupre", Analyse des matieres alimentaires, etc., p. 

 Agr. Exper. Stat. Kept., 1899, part 2, p. 132. 



6 Chem. Ztg., 1898, 22: 437-442; Analyst, 1899, 24: 41. 



; Winton, Conn. 



