Nutrition Investigations. 319 



solution. 1 The extracts, strained through cheese cloth, were digested 

 24 hours with malt diastase to free from starch, then concentrated to 

 a thick syrup on a water bath, and poured into three times their 

 volume of 95 per cent alcohol. A voluminous, flocculent, and some- 

 what fibrous, snow-white precipitate formed, which was filtered off, 

 pressed free from alcohol, redissolved in hot water, and reprecipitated. 

 (This was done largely to free it from sugar produced by the diges- 

 tion of the starch.) It was then transferred to absolute alcohol and 

 allowed to stand three or four days, after which it was washed with 

 ether, and dried in a vacuum desiccator. A somewhat coarse white 

 powder resulted, containing 6.94 per cent moisture and 0.74 per cent 

 ash. 2 It swelled up very readily in water, but dissolved exceedingly 

 slowly to a colorless, semi-transparent mucilaginous solution, which 

 did not reduce Fehling's solution, and examined in the polariscope, 

 after clarification with alumina cream, appeared optically inactive. 

 However, on reprecipitating the carbohydrate with alcohol, and 

 examining the alcoholic filtrate, sugar was found to be present in 

 small amount. A solution absolutely sugar-free became optically 

 active. A sample in which the sugar had been removed by fermen- 

 tation with yeast, was used to determine the specific rotation. The 

 following results were obtained: (1) A 2 per cent solution in a 200 

 mm. tube read —1.59°; applying corrections for moisture and ash, 

 [all, = —43.1°. (2) A sample containing in 100 cc. 0.5868 grams 

 mannan dried to constant weight at 105° C. read —0.48°; corrected 

 for 0.4 per cent ash, [a]^ = -43.8°. According to Thamm (276), 

 salep extract is inactive. In the above experiments, the levo-rotatory 

 nature of the mannan was at first obscured by the presence of traces 

 of reducing sugar formed by the hydrolysis of the starch, which could 

 not be detected by testing directly by FehHng's solution. Thamm, 

 however, in several ways carefully tested salep hydrolysis products 

 for dextrose with negative results, so that the only way to account for 

 these conflicting results seems to be to attribute it to difference in the 

 specimens of Orchis which furnished the mannan. 



Salep-extract is readily precipitated by Fehling's solution in floccu- 

 lent white masses. It is not precipitated by lead acetate in neutral 

 solution (nor, according to Thamm [276], in solutions of other neutral 

 salts), but is precipitated by basic lead acetate. 



A furfurol test was faintly positive, verifying the report of traces of 

 pentosans by Tollens and Widtsoe (163), and also by Thamm (276). 



45 liters of water to 100 grams salep powder, according to Thamm (276). 

 -Thamm found 0.483 per cent. 



