+44 
When we consider that the unchanged citrate both in '/,,, and 
in ‘/,, N solution delays the curdling more than 2 hours, it appears 
from the above table, that the action of citrate is very much weakened 
as soon as we substitute one of the active groups of the citricacid- 
molecule, that it totally stops as soon as we make 2 or 3 groups 
inactive. In the case of tartaric salts we find the same influence of 
groups; when the aleoholgroups are made inactive (by acetylation) 
or one of the carboxylgroups (by esterification), the inhibiting action 
has disappeared (has fallen to the order of magnitude of all kinds 
of indifferent substances. as is shown by the following figures). 
When one group which is substituted, is an alcoholgroup, we get 
a delay of 3°/,’ with an .*/,,,N and of 9°/, with */,, N. If seems 
very remarkable that the compared 3-basie acids without alcohol- 
group give a delay of the same order of magnitude, viz. 24 —3’ 
with Si. Nand, 97 Me wiken IN: 
When the one group that has been substituted, is a carboxyl 
group, we get a delay of 1°/,’ with */,,, N and of 6’/,’ with */,,.N. 
while with the bibasie acids compared, with 2 carboxylgroups and 
1 or more alcoholgroups, these figures are 1—1'/,’ with '/,,, N and 
6—61/,’ with '/,, N. Here also we find a remarkable agreement. : 
When 2 or more of the active groups of the citrates are taken 
away, the lengthening of curdling-time diminisbes to 0 a. '/,/ with 
1} 4, N and, ’/, a 17/,’ with ‘'/,, Ny figures which can be obfamied 
also with the compared substances but are in the same order of 
magnitude as with various indifferent salts. It is therefore better to 
say, I think, that when 1: or more groups are taken away, the 
characteristic action of citrate has quite disappeared. 
We can get a better insight into the relations here described, if 
we calculate what would be the concentration of citrate, necessary 
to give the same lengthening of curdling-time as a substituted citrate. 
For according to the figures on page 441 this lengthening increases 
much faster than in proportion to the concentration. 
We find then that a !enethening of curdling-time 
of 9'/,—9*/,’ corresponds with a citrate-concentration of 0.0023 N. 
» 6—6'/,’ on ais Ep °° O.OO2DNE 
EE) Ie EE LE) D0) EE) EE) PE) 0.0003 N. 
We can state therefore, that the characteristic citrate-action is 
diminished to about 6°/, of its original value, when one group has 
been taken away and is diminished to about 1°/,, when two groups 
are substituted. We have found, that an analogous influence on the 
curdling-time belongs to all salts which possess either three carboxy l- 
