210 



Dr. G. Senter. 



[June 2, 



Phenylhydrazine acetate does not retard the action quite so 

 strongly as hydroxylamine ; the constants decrease considerably during 



the action : 



Table X. 



Substance used. Constants. 



Phenylhydrazine acetate, m/5,000 0*0040 O'OOIO 



?7i/10,000 0-00610-0025 



m/20,000 0-00930-0041 



As in the former case, the free acid present retards the action, but 

 only to a small extent. 



Both hydroxylamine and phenylhydrazine are exceedingly poisonous 

 to the lower organisms, much less so to the higher animals.* They both 

 retard the catalysis of hydrogen peroxide by platinum to a considerable 

 extent, f Very few observations of their effect on enzymes have been 

 made. 



Formaldehyde. As is well known, this substance is very poisonous 

 for the lower organisms, and is now largely used as an antiseptic. 



According to Effront,| very minute amounts slow down the 

 hydrolysis of starch by diastase, on the other hand, it has little 

 influence on the activity of rennet. From the results given it is 

 clear that formaldehyde only slightly affects the activity of hsemase : 



Table XL 



Constants. 



Formaldehyde, m/1000 0-0300 



w/2000 0-0337 



Without formaldehyde 0'0372 



It may be mentioned that hydrogen peroxide does not appreciably 

 oxidise formaldehyde in the dilution used in these experiments. 



Effect of Mercuric Salts on the Reaction. 



Experiments have been carried out with mercuric chloride, bromide, 



and cyanide. The two former have an exceedingly toxic effect, while 



the latter has very little action : 



Table XII. 



Salt used. Constants. Salt used. Constants. 



HgCl 2 , w/250,000. . . -00200 -0004 HgBr 2 , w/80,000 ... '00400 0009 



m/600,000... 0-00330-0006 " w/200,000.. 0-00780-0032 



m/1,000,000 -00520 -0018 Hg(CN) 2 , m/400. ... -0154 



w/2,000,000 0-00980-0054 m/800. . . . '0213 



HgBr 2 , w/40,000 '00250 -0013 



Control experiment without mercuric salt -. '0250 



* Loew, loc. cit., pp. 39, et seq. 

 t Bredig, loc. cit., p. 76. 

 I Effront, ' Enzymes,' p. 117. 

 Oppenheimer, loc. cit., p. 114. 



