I9I4] A. W. Thotnas 213 



crystallized in the form of waxy leaflets melting at 45-48° C. Its 

 empirical formula is C24H48O2. 



(12) The filtrate from (8) is freed from lead salts by treat- 

 ment with hydrogen sulfide and, on evaporation, fatty glycerides 

 may be obtained. 



(13) The original filtrate (2), is shaken out with ether and the 

 ether sol. (14) evaporated in a beaker over about 75 c.c. of water. 

 The water sol. may contain, besides di-hydroxy stearic acid, nitric 

 acid and other Compounds soluble in ether. The nitric acid is elim- 

 inated by repeated washing of the ether extract with water and sub- 

 sequent evaporation of the ether, as before, over water. The water 

 is boiled, conc. to a small volume and filtered while hot through a 

 small wet paper, thus separating the di-hydroxy stearic acid'*^ which 

 is soluble in hot water from insoluble oily and resinous impurities. 

 On cooling, and standing for several hours, the di-hydroxy stearic 

 acid crystallizes out in star-like Clusters of leaflets which can be 

 identified with the microscope and from their melting point. 



Di-hydroxy stearic acid: C1SH36O4; m.p., 98-99° C. ; very 

 slightly soluble in cold water, quite soluble in hot water; very sol- 

 uble in alcohol and ether; water sol. is acid to litmus and decom- 

 poses carbonates of barium and calcium ; barium salt crystallizes in 

 somewhat characteristic globular concretions of radiating struc- 

 ture ; silver salt is amorphous and quite insoluble in water. 



(15) The sol., after extraction with ether, is neutralized with 

 sodium hydroxide and filtered. The precipitate which may be 

 formed during the neutralization is saved for treatment under (25). 

 The neutral filtrate is divided into three aliquot portions. One of 

 them (16) is precipitated with lead acetate, which removes much 

 coloring matter, and the precipitate is discarded. To the filtrate 

 (17) ammonia is added until slightly alkaline, and the Solution is 

 filtered. The precipitate (18) is decomposed with hydrogen sulfide, 

 filtered to remove lead sulfide, and the filtrate boiled down to a 

 small volume. After cooling, three volumes of alcohol are added 

 and the mixture is allowed to stand over night. If a gelatinous 

 precipitate (19) be formed, it is filtered off, washed with alcohol, 

 and tested for pentosans^'^ by the following methods (A-C) : 



1° Schreiner and Shorey: The Isolation of di-hydroxj' stearic acid from soils, 

 Journ. Amer. Client. Soc, 1908, xxx, p. 1599. 



11 Shorey and Lathrop : Pentosans in soils, ibid., 1910, xxxii, p. 1680. 



