236 ALBUMINOIDS. 



rapidly filtered off with the help of a filter-pump, washed with 40 

 to 50 per cent, spirit, finally vdth. absolute alcohol and with ether, 

 dried and weighed. 



§ 227. Isolation, of Väell in, etc. — Grains of vitelhn^ (aleurone, etc.) 

 may be frequently isolated from substances containing them in 

 large quantities, by a process of elutriation Avith olive oil,- or a 

 mixture of oil and petroleum spirit. ^ Freed from oil with 

 petroleum spirit, vitellin dissolves in water at 30° to 40°, and can 

 be precipitated from such a solution by a current of carbonic acid. 

 To obtain it in crystals the precipitate is digested with calcined 

 magnesia at 35°, filtered whilst warm and cooled. Schmiedeberg 

 considers these crystalloids, as well as aleurone itself, to be 

 compounds of vitellin Avith alkalies or alkaline earths. The 

 crystals are doubly refracting. 



§ 228. Sejmration of Vitellin from Myosin. — According to Weyl,'^ 

 vegetable vitellin may be distinguished from vegetable myosin by 

 requiring, in a solution containing 10 per cent, of common salt, a 

 temperature of 75° for coagulation, whilst myosin coagulates at 

 bo^ to 60°. The latter, Avhich has also been found in potatoes, 

 j)asses into solution when the residue, after treatment with water, 

 is macerated with 10 per cent, solution of salt. Small pieces of 

 rock-salt suspended in such a solution (previously neutralized with 

 carbonate of soda) cause the gradual precipitation of the myosin, 

 which, however, can be redissolved by the addition of a little 

 water. Myosin may be separated from vitellin by diluting the 

 solution largely with water, i)recipitating both with carbonic acid, 

 dissolving in dilute salt-solution and coagulating at the tempera- 

 ture stated. 



^5 229. Estimation. — Experiments made by Liborius,^ Girgen- 

 sohn,^ and Taraskewicz,^ have shown that the albumen of blood- 

 serum, eggs, etc., can be estimated with tolerable accuracy by 



' A similar substance occurs in the seeds of I'inus cembra. See Schuppe, 

 Pharm. Zeitschr. f. Kussland, .'520, 1880. 



- Compare Maschke, Chem. Centralblatt, 864, 18.''»8, and Sachsse, ibid. 583, 

 1876 (.Journ. Chem. Soc. xxxii. 200). 



•* Compare Schmiedeberg, Zeitschr. f. phys. Chem. i. 206 ; Ritthausen, 

 Archiv f. die ges. Phys. xvi. 301 (.Journ. Chem. Soc. xxxiv. 518). 



•* Loc. cil. 



■'■ ' Beitr z. quant. Eiweissbest. Diss. Dorpat, 1870. 



'' 'Beitr. z. Albuminometrie und z. Kenntnissd. Tanninverb. d. Albuminate. 

 Diss. Dorpat, 1872. 



^ Einige Methoden z. Werthbest d. Milch. Diss. Dorpat, 1873. 



