NOVEMBEE 1, 1901.] 



SCIENCE. 



691 



Die Krystallisation von Eiweissstoffen und ihre 



Bedeutung fur die Eiweisschemie. Von Dr. 



Fb. N. Schulz. Jena, Gustav Fischer. 



Pp. 43. 1901. 



Not many years have passed since it was cus- 

 tomary for physiological chemists, following the 

 suggestion of Thomas Graham, to class proteid 

 substances as colloids, in distinction from the 

 crystalloids which readily pass through diffusion 

 membranes. The fact that native proteids are 

 indiffusible no longer necessarily implies that 

 they are not capable of crystallization. The 

 achievements of recent years in the preparation 

 of various proteids, both animal and vegetable, 

 in crystalline form have marked a great ad- 

 vance in the study of this important group of 

 organic compounds. The prominent role which 

 the proteids assume in the life-processes of all 

 organisms has long made them conspicuous ob- 

 jects of investigation ; and now that the pos- 

 sibility of separating them in crystalline form 

 has given promise of improvements in the 

 methods of purification and identification, a 

 new impetus has been given to the investiga- 

 tion of the chemistry of the proteids. 



Professor Schulz' s monograph is a comprehen- 

 sive compilation of the literature on the crys- 

 tallization of the proteids. It includes a re- 

 view of the occurrence of proteid crystals 

 ready-formed in animal and plant tissues, and 

 a more extensive description of the separa- 

 tion and properties of crystalline preparations 

 from non-crystalline native proteid mixtures. 

 This includes in particular the crystallization 

 of egg- and serum-albumin and the readily 

 obtained vegetable proteids. Other less cer- 

 tain instances (fibrin, casein, heteroalbumose, 

 etc.) are considered in the light of the evidence 

 at present available. Hsemoglobin and re- 

 lated compounds are treated in somewhat 

 greater detail, which their earlier discovery 

 justifies. It is a matter of historical interest 

 to note that Schulz names B. Reichert as the 

 discoverer of the blood crystals (1847), whereas 

 this honor is usually assigned to Otto Funke 

 (1851). 



In the concluding pages of Schulz's mono- 

 graph brief reference is made to the crystallog- 

 raphy of the proteid crystals and the signifi- 

 cance of crystallization for the chemistry of 



the proteids. It is a satisfaction to American 

 readers to find the American contributions to 

 the literature of the subject adequately re- 

 ported by a German writer. Dr. Schulz is a 

 professor at Jena. 



Lafayette B. Mendel. 

 Sheffield Scientific School of 

 Yale University. 



SOCIETIES AND ACADE3IIES. 

 chemical society of WASHINGTON. 



The 128th regular meeting of the Washing- 

 ton Section of the American Chemical Society 

 was held at Cosmos Club Hall, Thursday even- 

 ing, October 10. The following program, was 

 presented : 



Dr. H. N. Stokes, ' Pyrite and Marcasite.' 

 Dr. Stokes stated that the physical character- 

 istics by which these geologically important 

 dimorphous forms of iron disulphide are dis- 

 tinguished are not always applicable, especially 

 when they occur in the form of concretions. 

 The paper describes a method by which they 

 can always be determined, which consists in 

 boiling an excess of the carefully prepared 

 mineral with a standard solution of ferric am- 

 monium alum, under absolute exclusion of air, 

 until the alum is completely reduced. The re- 

 action takes place in two stages : 



(1) FeSj-l-Fe^ (804)3 = 3 FeSO, + 2 S. 



(2) 2 S + 6 Fe2 (80^)3 -|- 8 H^O = 12 FeSO^ 



+ 8 H^SO,. 



The second reaction is always incomplete, 

 only a portion of the sulphur being oxidized to 

 sulphuric acid. Under the standard conditions 

 the percentage of sulphur oxidized is 60.4 in 

 the case of pyrite and 18 in that of marcasite. 

 The percentage of sulphur oxidized, or the oxi- 

 dation coefficient (p), is obtained from the equa- 

 tion 



8.333 6 



P 



-25, 



which is deduced from the above equations, 

 and in which a, b and c represent the perman- 

 ganate equivalents of the standard solution and 

 of the ferrous iron and total iron of the re- 

 sulting solution, respectively. The proportion 

 of the minerals in a mixture of both can be 



