Emmctt and McKim56 state that the yeast vitamin is not absorbed by kieselguhr or infusorial earths, but Brill57 found that the curative principle from rice polishings is extracted by infusorial earth, although not by as small a proportion of the earth as was used of the Lloyd reagent by Seidell. Brill considers this partial extraction to be due to the character of the extract. There appears to be a loss of antineuritic power in the extract as it ages. He regards the method inapplicable, because of the quantity of earth needed completely to extract the total vitamin content.

The water-soluble vitamin appears to be stable towards acids.58 Alcohol saturated with hydrochloric acid is frequently used to extract it from the food substances in which it is contained.59 McCol-lum and Simmonds60 found some indication that it may be slowly inactivated by this acid, but the evidence is not conclusive, and the action is certainly inconsiderable. Similarly with nitrous acid, 81 the vitamin may be destroyed to some slight extent, but very slowly if at all, and the same may perhaps be true of sulphuric acid.62

On the other hand, after hydrolysis with mineral acids, extracts of rice polishings have been found to be more efficacious as an antineuritic factor than before such treatment,63 a result which may be due to the liberating of the active constituent from a less active compound present in the original extract.64

56 Emmett and McKim, J. Biol. Chem. 3a, 409.

57 Brill, Phil. J. Sci. 12, 199, 1917.

58 Punk, 1. a; Voegtlin, Wash. Acad. Sci. Oct. 4, 1916; Abstr. in Nature, 98, 373; Steenbock, Proc. Am. Physiol. Soc. Am. J. Physiol. 4a, 610, 1917; Whipple, J. Biol. Ch. 44, 175, 1920.

59 Funk, 1. c; Eddy, J. Biol. Chem. 37, 113, 1916; Brill and Alcaatre, Phil. J. Sci. 12A, 127, 1917; Myers and Voegtlin, J. Biol. Chem. 42, 199, 1920.

60 McCollum and Simmonds, J. Biol. Chem. 33, 55, 1918.

61 McCollum and Simmonds, J. Biol. Chem. 33, 55, 1918. 62 Drummond, Bioch. J. 11, 255, 1917.

63 Vedder and Williams, Phil. J. Sci. B. 1913, 8, 175; Williams and Sa-leeby, Ibid, 1915, zo, 99; Sullivan and Voegtlin, Proc. Soc. Biol. Chem. 1915, J. Biol. Chem. 24, xvii, 1915-16.

Osborne and Wakeman 65 prepared an extract from yeast by running washed brewers yeast into boiling 0.01 N. acetic acid, the ex-tract thus prepared being said to contain almost all the growth-promoting vitamin of the yeast. An attempt to precipitate the vitamin fractionally from the evaporated filtrate by means of increasing concentrations of added alcohol was, however, only partially successful.

It is said 66 to be stable to concentrated alkalis at room temperature, but the evidence regarding its sensitiveness to dilute alkalis at boiling temperature is conflicting. Boiling for an hour with 0.28 per cent sodium hydroxide solution destroyed the antineuritic content of wheat embryo almost entirely.67 Fraser and Stanton68 inferred from their experiments with rice polishings that 0.5 per cent sodium hydroxide solution destroyed the antineuritic substance.

Voegtlin and Lake69 produced typical symptoms of polyneuritis in cats and dogs by feeding meat which had been treated with a 10 per cent sodium carbonate solution until distinctly alkaline and then heated to 120° C. for three hours. Meat which had been heated to this temperature for three hours without the addition of alkali had not completely lost its antinueritic power. Commenting on this work,70 Osborne and Mendel say:

Voegtlin and Lake assume that their ground beef muscle which was treated with 10 per cent sodium carbonate solution until the tissue reacted strongly alkaline to litmus and then heated at 120° under pressure for three hours, was free from B, but six rats whose sole food consisted of meat thus treated, lived for more than three months and gained in weight, one even living for about seven months and gaining 150 per cent in weight. Osborne and Mendel71 found that dried lean round of beef (untreated) furnishes so little of this vitamin that animals fail almost as quickly when this is the sole source of protein as when the extracted meat residue is used. Contrasting Voegtlin and Lake's results with those obtained by Osborne and Mendel with meat which was extracted with boiling water only, it is difficult to believe that the treatment with alkali was responsible for loss of vitamin. They cannot account for the good results with rats on this diet.

64 Williams and Seidell, J. Biol. Ghem. a6, 431, 1916; Daniels and Mc-Clurg, Ibid. 37, 201, 1919.

65 Osborne and Wakeman, J. Biol. Chem. 40, 383, 1919.

66Steenbock, 1. c; Williams and Seidell, J. Biol. Chem. 36, 431, 1916.

67 McCollum and Simmonds, 1. c.

68Fraser and Stanton, Lancet 1915, i, 1021.

69Voegtlin and Lake, J. Pharmacol. II, 167, 1918; Am. J. Physiol. 47, 558, 1918.

70Osborne and Mendel, J. Biol. Chem. 39, 42, 1919.

71Osborne and Mendel, J. Biol. Chem. 32, 309.