i68 
THE ENERGY OF THE LIVING PROTOPLASM. 
aluminium chloride in the synthesis of hydrocarbons, that of 
zinc chloride in the transformation of glycol into aldehyde, and 
the accelerating action of iron and copper salts upon the 
oxidation of phenol by peroxide of hydrogen. (I) 
The genuine katalytic actions may be divided into three 
groups : 
1. Katalysis by labile organic compounds, 
2. Katalysis by mineral acids, caustic lyes, and certain salts, 
3. Katalysis by finely divided metals. 
In regard to the first group may be mentioned the conversion 
of dicyanogen into oxamide by a dilute solution of ethylic 
aldehyde, a reaction observed by Liebig ; the transformation of 
thiourea into the isomeric ammonium thiocyanate by an alcoholic 
solution of ethyl nitrite (Claus) ; the facilitating action of acetic 
ester upon the combination of hydrocyanic with hydrochloric acid 
(Claisen and Mathews ). Maleic acid transforms ketazines into the 
isomeric pyrazolines with liberation of heat, (2) whilst fumaric 
acid can only accomplish this at a temperature of 100. 0 To this 
group of actions belongs evidently not only the action of the 
living cells, but also the action of the enzymes, which have a 
high degree of lability and betray, by their easily passing into an 
inactive state, as well as by their proteic nature, a certain rela¬ 
tion to the proteids of the living protoplasm. The fact that 
dilute formic aldehyde destroys their activity even in perfectly 
neutral solution at the ordinary temperature, makes the presence 
of highly labile amido-groups probable. (3) 
(1) Chem. Centralbl. 1885, p. 224. In certain cases the apparently katalytically 
acting substance is mainly a suitable medium to bring two compounds into more 
intimate contact with each other, or by combining with one of two compounds pre¬ 
sent to help to loosen somewhat certain affinities in the molecule, and thereby bring 
about combination with the second compound. 
(2) Curtins and Foersterling, Ber. D. Chem. Ges. 27 , 770. F. Stohmann deter¬ 
mined the thermic value of maleic acid to be 326.3 cal. and that of fumaric to be 319.7 ; 
the latter possesses, therefore, less energy than the former. Stohmamb recognised by 
direct experiment, in determining with great exactness the heat of combustion, that 
labile compounds always have a higher thermic value than the isomeric stable ones. 
(3) O. Locw , Jahresber. f. Thierchem. 1888. I have observed also that a solution 
of prussic acid of 25 °/ 0 destroys in twelve hours the diastatic but not the pro¬ 
teolytic enzyme of the pancreas (Pflüg. Arch. 27 , 208). Cf. also Schär and Fichtcr, 
Jahresber f. Thierchem. ,3, 269. Certain bacterial enzymes are rendered inactive by 
sulphuretted hydrogen (Fermi and Bcrnossi. 1894). Chloroform retards enzyme-action 
(Salkowski). According to Arsonvale (1894) enzymes are rendered inactive by a 
temperature of—I50°C. 
