( 181 ) 
more rapidly so that addition of very little hydrochloric acid suffices 
for the complete conversion. 
The substance was again dissolved in glacial acetic acid and 3 ce. 
of a solution of dry hydrogenchloride in glacial acetic acid were 
added. The quantity of HCl thus introduced into 500 ec. of the 
solution amounted to only 0.0135 gram or not quite '/,,, part of the 
quantity present in the experiment with aqueous acetic acid. 
The progressive change of the reaction was as follows: 
t in hours ee Nao 5,0, 
0 ale 
oy 29.7 
1 28 
En 24 
2 22.6 
Di 19.8 
3 WED 
ot. 14.2 
4 12.4 
4'/, 10.5 
: 5 1 A 
On calculating A according to the formula == ae ee it will 
be seen that it keeps on increasing; this shows that the amount of 
the catalyser increases. On repeating the experiment it was found 
that, after the reaction, more hydrochloric acid existed (weighed as 
Ag Cl) than corresponded with the quantity added. 
A graphic representation of the above figures plainly shows that 
we are dealing here with a reaction the velocity of which has been 
accelerated by an increase of the catalyser *). In the experiment with 
20 per cent acetic acid the small increase of the relatively large 
amount of HCl is not perceptible. 
Even when we do not add hydrochloric acid but set the acetic 
acid solution aside in the dark we meet with the same type of 
progressive change of the reaction. 10 ¢.c. of a solution in glacial 
acetic acid were titrated from day to day and took: 
13,12, 9, 6,7 72,6 TD ands Ll 6.¢, Nas POE 
which figures again reveal the character of a reaction accelerated 
by a catalyser. It moreover shows that it is not the glacial acetie 
acid which starts and continues the reaction, but that the conversion 
is due to the catalyser formed from the product itself; in the first 
1) Osrwatp, Lehrb. d. allgem. Chem. Bd. Il, T. Il, 266. 
