23 
assume a very acid reaction. In the latter case a considerable rise of 
temperature is noticed." 
BEHAVIOR TOWARD MERCURIC CHLORID. 
Two grams of cured tobacco containing a@- and f-catalase were 
left two days in 2 ce. of a 0.1 per cent solution of mercuric chlorid. 
While the filtrate showed no reaction whatever on hydrogen peroxid, 
the insoluble part still showed a slight reaction. Suspended in 30 ce. 
water, it yielded on addition of 10 cc. hydrogen peroxid: 
Oxygen in thirty minutes. 
A Slee, CECAmieis Wabi tot ise es ewes os ee 2 6 
CRRREGE ey en ee ese So AS st eee. Seer 158 
This reveals a highly injurious influence of mercuric chlorid on both 
kinds of catalase. The f-catalase of one gram of the sample yielded 
16.5 ce. oxygen in thirty minutes. Hence, even on the assumption 
that all (-catalase had been merely precipitated by the mercuric 
chlorid and thus withdrawn from the solution, and further assuming 
that it was in the first place the a-catalasé that had been killed by that 
salt, an injury due to 4-catalase would still be evident. 
Catalase is probably also injured by various salts of other heavy 
metals, but the results obtained upon addition of hydrogen peroxid to 
such mixtures would be misleading, since many salts of these metals 
themselves bring on decomposition of hydrogen peroxid. 
BEHAVIOR TOWARD ACIDS AND BASES. 
It isa noticeable fact that while highly dilute acids retard the action 
of a- and f-catalase, dilute alkaline solutions promote it. In one case 
it was shown that on addition of 1 per cent sodium carbonate to a 
mixture of 10 ce. cold-prepared tobacco extract with 10 ce. hydrogen 
peroxid, 165 cc. of oxygen were developed in five minutes, while it 
took fourteen minutes to develop the same amount of oxygen when 
sodium carbonate was absent. 
When the amount of acids in the solutions reaches more than 0.5 per 
_ cent, the a- and f-catalase are very soon killed. The following obser- 
vations may be mentioned: Two grams of finely powdered sweated 
tobacco were shaken with 40 cc. of a 2 per cent solution of oxalic 
acid and the mixture neutralized after thirty minutes, with caustic 
soda. The catalytic power was entirely destroyed. No trace of oxy- 
‘Jacobson’s inferences as to the injurious influence of potassium sulpho-cyanide 
upon the ‘‘catalytic property of diastase, emulsin, ete.,’’ must be corrected accord- 
ingly, since it is the acid reaction of mono-potassium sulphate formed by the hydro- 
gen peroxid which interferes with the result, and not the sulpho-cyanide as such. 
Furthermore, it is not diastase and emulsin, but a separate enzym, that causes the 
‘‘catalysis of hydrogen peroxid”’ as here set forth. 
