vii HALOGEN-ALBUMINS 235 



From the biological point of view it is interesting that sponges, 

 corals, and the thyroid glands of mammals possess the power of 

 de-ionising and of storing in large amounts iodine, which is offered 

 them in minimal quantities and in the state of an ion. That 

 gorgonin and iodo-spongin are by no means examples of maximal 

 iodisation is shown by the observations of Hundeshagen, 1 who found 

 in tropical horny sponges 8 to 14 per cent of iodine, while the 

 ordinary bath sponge contains on the whole only 1'5 to 1'6 per cent. 

 Young sponges and corals, and the thyroid glands of young animals, 

 contain considerably less iodine. 



Other Halogen-Albumins 



Blum and Vaubel 2 and Hopkins 3 have shown that the other 

 halogens bromine, chlorine, arid fluorine may be introduced into the 

 albumin -molecule quite analogously to iodine. Generally speaking, 

 the method was the same as in iodising ; chlorination was performed 

 at room - temperature ; Blum has introduced chlorine also electroly- 

 tically. The halogen -content of albumins prepared in this way 

 corresponds with that of iodine ; for egg-albumin were found by 



Hopkins. Blum. 



6 '2 per cent Iodine. 6-7 per cent Iodine. 



3'84 Bromine. 4-5 . Bromine. 



1-93 Chlorine. 2 Chlorine. 



1-2 Fluorine. 



A number of fluorine compounds have been prepared by Gans. 4 

 In addition to the bromine-albumins just mentioned, Hopkins and 

 Pinkus have also prepared more highly halogenated bodies with more 

 loosely bound bromine, corresponding to the per-iodo-casein. They 

 found the following maximal percentage values 



Egg-albumin, crystallised . ^ 12 '6-1 6 '4 3 



Serum-albumin . . . 12 '15-1 2 '94 



Serum-globulin . . 13'53-14'03 



Casein . . . . 11-17 



Albumoses .... 16 '3-1 7 '6 3 



| ; According^to Harnack many of the technically prepared halogen 



1 F. Hundeshagen, Zeitschr. f. angew. Chem. 1895, p. 473 ; according to Chem. 

 ZentraM. 1895, p. 570. 



2 F. Blum and W. Vaubel, Journ. f. praU. Chem. [2] 56. 393 (1897), 57. 365 

 (1898). 



3 F. G. Hopkins, Ber. d. deutsch. chem. Ges. 30. II. 1860 "(1897) ; F. G. Hopkins 

 and S. N. Pinkus, ibid. 31. II. 1311 (1898). 



4 L. W. Gans, Patentschrift, Chem. ZentralU. 1901, I. p. 148. 



