21 
four hours, again salted out by ammonium sulphate, and washed well 
by a concentrated solution of this salt. Upon redissolving it in 20 ce. 
rater and adding 10 cc. hydrogen peroxid, it still developed 92 ce. , 
oxygen in fifteen minutes, while in the control case 98 cc. were 
obtained; hence the enzym itself is not injured by potassium nitrate. 
The depressing influence of nitrates is seen from the following test: 
Two portions of an extract of sweated tobacco received an addition of 
5 per cent potassium nitrate and 5 per cent magnesium sulphate (cryst.), 
respectively. Immediately afterwards 20 ce. of each of these liquids 
were mixed with 10 cc. hydrogen peroxid. The result was: - 
Oxygen developed in five minutes. 
cc. 
In ‘presence. pr potasaiuen maiie Soe oh ne oF 2 2s 3 28 oe 3S oe eee 15 
in presence of maceesinm silphate... = 9 2's.2 - eke. 1S eee 88 
Control 222-22 ee ee ee A ee ee Bane eS Sak seme oe eka eR 105 
Nitrates have no such depressing influence upon the corresponding 
action of finely divided platinum. A mixture was prepared of 5 ce. 
hydrogen peroxid, 20 cc. water, 2 grams potassium nitrate, and a trace 
of platinum black. Here 28 cc. oxygen were developed in fifteen 
minutes, while in the control case 31.6 cc. were evolved. This shows 
that the contact of the nitrate with the enzym itself can be the only 
cause of the retardation just mentioned. 
In some other tests the time necessary to develop a certain volume 
of oxygen was observed. One gram of crude /-catalase, prepared by 
salting out a concentrated extract of sweated tobacco and drying at 
the ordinary temperature, was dissolved in 500 cc. water. To differ- 
ent portions, each containing 5 cc., of this highly diluted solution, 20 
cc. water and 0.5 gram of various salts were added. After a further 
addition of 5 ce. of nearly neutral hydrogen peroxid the time neces- 
sary for the production of 40 cc. of oxygen was observed. The mixture 
was frequently shaken. The number of minutes required to produce 
40 ec. of oxygen in the presence of various salts was as follows: — 
Minutes. 
Pe aocaertipe nlOnitmes nee ere, ee ae Me eo NS Sie chs sc aks Se oe 43 
Pils DOL MI ChOnyiy = areas ke Fee ci ee oe sade le eee 4¢ 
MeEbosipotaissmiml pplorpmates. Yee te he ne eee eee 43 
See pntancinina alata ee Se ed ree oh Low b eo oa a ee eee 83 
Pe cOaatia pr Ae Ahi ee, oe 8 a tye Sa tale egels Fie woe Bee ee 63 
Uae ePROOGMISTIV ARIA LEE as iota he aco he Ss ds ale Sonn Je ee he ee 103 
eRe Riticd Ue ISMENIGR ALE OS Pa a ok nn ae a ad oe * ROM om eee 33 
Puntent aeaiion or salte—control. 2. 5.2252 k.20 el ec. Le +5 
While in this case the mixtures had a weak acid reaction, they had 
in the following experiment a weak alkaline reaction. The enzym, 
furthermore, was applied in double the concentration used before, 
and, with one exception, the amount of salts applied was increased to 
' The depression of the catalytic power of pancreas and almond extract by potassium 
nitrate was also observed by Jacobson in 1892. 
