§ 120. FIXED OIL, ETC- 99 



IX. 



Special Methods for the Estimation of certain Consti- 

 tuents OF Plants, Supplementary Notes to the Pre- 

 ceding Experiments. 



fats and their constituents ; CHOLESTERIN, FILICIN, ETC. 



§ 120. Estimation of Fixed Oils. — For reasons given in § 8, I 

 recommended the use of benzene some twenty years ago^ for 

 extracting fixed oils. Petroleum spirit, which I subsequently 

 introduced for the same purpose, has the advantage over benzene 

 of being more volatile and possessing a lesser solvent power for 

 resins, etc. (Cf. § 36.) The xise of benzene was afterwards 

 advocated by Hoffmann- also, who gave it the preference over 

 ether and bisul})hide of carl)on. Other methods for estimating 

 fixed oils have been described by Munch. ^ Various forms of 

 ajiparatus that may be used have formed the suljjects of commu- 

 nications from Storch,"* Wagner/^ Simon,*5 Toliens,^ Schulze,^ 

 Tschaplowitz,^ Medicus,^*^ Siewert,^^ Hirschsohn,^- Keyser,^^ and 

 others. 



The apparatus represented in Fig. 5 is that last devised by 

 Toll ens. It consists of a weighed fiask. A, holding about 100 cc, 

 to which is tightly fitted, by means of a perforated cork, a glass 

 tube B ; the latter is altout 30 mm. in diameter at its upper, and 



^ Pharm. Zeitschr. f. lliissland, i. 44, 1862 ; Anm. Zeitschr. f. anal. Chem. 

 i. 490. 



^ Zeitschr. f. anal. Chemie, vi. 368, 1867. 

 =* N. Jahrb. f. Pharm, xxv. 8, 1866. 



* Zeitschr. f. anal. Chemie, vii. 68, 1868. ^ jbid. ix. 354, 1870. 



6 Ibid. xii. 179, 1873 (Journ. Chem. Soc. xxvii. 293). 

 ^ Ibid. xiv. 82, 1875, and xvii. 320, 1878. « ib;(j_ ^vü. 174, 1878. 



9 Ibid. xviii. 441, 1879. " Ibid. xix. 163, 1880. 



^1 Landw. Versuchsst. xxiii. 317, 1879 (Journ. Chem. Soc. xxxvi. 558). 

 1- Archiv d. Pharm. [3], x. 486, 1877. " Farm. Tidskr. 1880, Nos. 9 and 19. 



7—2 



