VITAMIN B (B,) 65 



The silica gel-vitamin complex was washed at pH 3, suspended in 

 6 liters of water, and the vitamins were extracted at pH 9.8. This 

 vitamin-rich solution was neutralized and concentrated, inactive mate- 

 rial was precipitated by adding an equal volume of 95 per cent alcohol, 

 and the supernatant fluid was poured into acetone. The resulting pre- 

 cipitate contained a high concentration of vitamin B (Bi) and some 

 vitamin G (B2). This preparation, of which 2.2 milligram daily, or 0.07 

 milligram when supplemented with the heat-stable factor, supported 

 normal growth (18 to 24 days) was apparently about 30 times as 

 rich in vitamin B (Bi) as in vitamin G (B2). It was soluble in water 

 and partly soluble in alcohol. It gave negative biuret and Millon tests, 

 and reduced Fehling's solution only after hydrolysis. Upon heating 

 with strong alkali, hydrogen sulfide was evolved, as demonstrated 

 by means of lead acetate, and a strong odor of indole or skatole 

 was developed (Cf. Guha and Drummond, 1929). It showed the 

 following composition: C, 31.54; H, 4.99; N, 8.92; NH2, 1.9; P, 8.92 

 per cent. 



Levene also reported at this time that by deaminizing the starting 

 material with nitrous acid before adsorption on silica gel it was pos- 

 sible to obtain a concentrate of Bi containing no detectable quantities 

 of the heat-stable material (B2). 



Williams and Eddy (1927-28), in their investigation already re- 

 ferred to in the previous section, compared the activity of various yeast 

 concentrates on pigeons and rats by conducting 60-day feeding experi- 

 ments on young rats with the materials being tested as the source of 

 vitamin B and determining the minimum protective dose against poly- 

 neuritis in adult pigeons on a polished rice diet in a 30- to 40-day test, 

 and concluded that per unit weight young rats used about 10 times 

 as much vitamin Bi as adult pigeons. 



As has also been noted in the previous section, Guha and Drummond 

 (1929) followed the various steps in the concentrations of vitamin 

 Bi by tests on both rats and pigeons. 



The rat tests were carried out by studying the influence of the sup- 

 plement on the growth of rats whose development had been inhibited 

 by a diet deficient in vitamin Bi. Young rats averaging 50 grams in 

 weight, kept in separate cages with screened bottoms, were fed a basal 

 diet consisting of 75 per cent rice starch, 21 per cent commercial 

 casein and 4 per cent salt mixture (McCoUum), with a daily supple- 

 ment of 1 drop of cod-liver oil, and 1 cubic centimeter of a 50 per cent 

 solution of marmite (a commercial yeast preparation) autoclaved for 

 3 hours at 14 to 15 pounds pressure in an alkaline medium. Compari- 



