INVESTIGATIONS ON HARMFULNESS. 53 



the numbers in italics are those of the permitted list of Food Inspec- 

 tion Decision 76: (55) Ponceau 2 R, (65) Fast Red B, (434) Light 

 Green SF bluish, (56) Ponceau 3 R, and (106) New Coccin. 



The following precipitated in all but the fifth strength: (107) 

 Amaranth. 



The following precipitated only the first three strengths: (14) 

 Orange G and (85) Orange I. 



The following precipitated only the first two strengths: (462) Acid 

 Magenta. 



For the basic colors the method of testing was different from that 

 described for the acid colors and the amounts employed were not so 

 definitely set forth. A 1 per cent solution of serum albuminoid was 

 employed; the solution of coloring matter used varied in strength 

 from 0.5 to 1 per cent (&), a "very dilute solution" (a) being also 

 employed. The annotations given by the author (p. 1 14) are herewith 

 reproduced in full : 



(17) Chrysoidin Y. (a) In a very dilute solution the yellow base is at once liber- 

 ated, and when sufficient color is added albumen precipitation takes place. No color 

 change on heating. (6) Turns yellow at once. Further additional color produces a 

 brown and albumen precipitation. 



(201) Manchester Brown, (a) Becomes yellow at once, due to separation of the 

 free base. On heating no change, (b) Becomes a discolored brown, and produces a 

 nice brown albumen precipitate. 



(425) Auramin O. (a) No change. (6) Precipitates albumen strongly. 



(427) Malachite Green. (The oxalate of the color was used.) (a) Color changes 

 from a blue-green to a more pure green. (6) Cold, no precipitation of albumen; 

 heated, sudden precipitation of albumen. 



(428) Brilliant Green. (A sulphate of the color was used.) (a) Becomes milky. 

 (6) Immediate precipitation of albumen. 



(448) Magenta. (Acetate and nitrate were used, and in both acted the same.) (a) 

 Color changes from yellowish-red to rose-red. (6) Albumen precipitation abundant, 

 even in the cold. 



(451) Crystal Violet, (a) The color loses its reddish cast and changes to pure blue. 

 (6) Albumen precipitated by the use of much color. 



(4) Naphthol Yellow S was tested as the free-color acid and not as the sodium or potas- 

 sium salt, which is its commercial form. It precipitated the albuminoid from the 

 following solutions: 1. 1 per cent serum albumen in water. 2. 0.5 per cent serum 

 albumen in 10 per cent acetic acid. 3. Casein, 0.5 per cent in 10 per cent acetic acid. 

 4, Serum albumen; 5, Casein; 6, Nuclein, all in 0.5 per cent solution in 0.2 per cent 

 sodium hydroxid. 7. Nucleinic acid in 0.5 per cent water solution. 



The relationship between the amounts of color-acid and albuminoid 

 solution here used does not appear definitely in the book. 



Having reference now to the literature and the physiological 

 action, as compiled herein, it will be observed that the ability to pre- 

 cipitate albumen, or not to precipitate it, under the conditions of 

 Heidenhain, appears not to have any direct connection with the 

 results obtained by actual physiological test on animals or man. 

 For instance, among the five that precipitated all five strengths of 



