( 623 ) 



3. p-Bromohenzoic acid, lu.p. 252' was obtained by me in tiny 

 crystals from ethyl acetate -|- benzene but they were very badly 

 formed. They are monoclinic and probably quite isoraorphous with 

 (he two other acids. The angle of inclination amounts to about TS'/,". 



4. p-Iodobenzoic acid has not as yet been obtained in measurable 

 crystals owing to its little solubility in most of the organic solvents. 

 Its melting point is situated at 2t?7°, therefore higher than that of 

 the J5/'-derivative. A direct isomorphism with the three other halogen 

 benzoic acids is not improbable. 



Physiology. — "On catalases of the blood". By L. van Itallie. 

 (Communicated by Prof. C. A. Pekelharing.) 



(Communicated in the meeting of December 30, 1905). 



The discovery made by Thenard that bloodtibrine possesses the 

 pi'operty of decomposing hydrogenpero.xide has also been extended 

 to defibrinated blood, by Schönbein {Joum. f. pi'akt. Chemie 89, 

 22). It has found a practical application in the judicial investi- 

 gation on bloodtraces and has been the object of manifold scientitic 

 investigations. A resuming report precedes the investigations by 

 Senter {Da^ Wasserstofsupero.vyd zersetzende Enzym des Blutes. 

 ZeiUchr. f. physik. Chemie 4A [1903] 257 — 318) to whose work we 

 refer the reader. Senter calls the enzyme which he has isolated 

 from blood Haemase whereas I myself prefer to use the name 

 of catalase, which has been given by LoEW {Catalase, A nen: enzym 

 of general occurrence, Report N". 68 V. S. Depart, of Agriculture. 

 Washington). 



Although the catalases, those enzymes which are able to split 

 H5O2 in water and oxygen, are universally scattered in the vegetable 

 and animal kingdom, it has as yet not been possible to isolate one 

 of these bodies in state of purity. 



Althougli different phenomena indicate that there exist more than 

 one catalase (apart from Loew's «- and f?-varieties) it has been 

 impossible as yet to discern them. 



The following communication gives a new contribution to the 

 properties of the catalases of the blood, which may perhaps lead to 

 a differentation of the catalases, and which at least gives an opportunity 

 of dividing the catalases of some animals into two groups. 



To Mr. C. J. Koning at Bussum I owe the communication that 

 human-blood diluted from 1^1000 heated at 63° for half an hour, 



