546 



d. One alcohol group raid one cavhoxyl yroup made inactive. 

 Methylene citric acid 43.4 cm' 5| 7« 



Compared with : 

 Ambric acid 

 Glutaric acid 

 Acetone dicarbonic acid 



e. Two carhoxijl groups made imictiue. 

 Citric acid dimethyl ester 

 Citro diamide 



f. Three groups made Inactive. 

 Citraniide 

 Di ethylester of citric acid monoamide 



Various indifferent salts of monovalent acids (sodium chloride, 

 cyanide, formiate, acetyl-salicylate etc.) consume 44.6 to 44.9 cm' 

 of titration liquid ; hence also three per cent less than water. 



I refer for the structure formulae of the examined compounds to 

 my previous publication '), where I have indicated them all. 



It appears from these experiments that substitution in the citrates 

 very considerably diminishes the action. If one group is made 

 inactive (it seems to be immaterial whether it is the alcohol group 

 or one of the carboxyl groups), about 11 or 12 V, of the calcium is 

 not found back in the titration (instead of 96 '/„). This quantity is, 

 therefore, bound in complexes in the Ca-ion concentration which 

 corresponds to the solubility of calcium oleate in an aicoliol-water- 

 mixture of about 17 volume percentages of alcohol (per 100 volume 

 percentages of liquid mixture). In these solutions the compared 

 citrates and substituted citrates are present in the same molecular 

 concentration. 



When two active groups are removed at the same time, about 

 5 or 57, 7o <jf '''® calcium appears to l)e bound in complexes, in 

 three groups only 3 '/,. 



To be able to ascertain to what concentrations of the not-sub- 

 stituted citrate these values correspond, I have carried out some 

 determinations with citrate of much weaker molecular concentration 

 (all this expressed in the same units as in the experiments described 

 before). 



citrate (0.0050 N) 35.9 cm' 24 "/„ 



citrate (0.0025 N) 42.55 cm' 7.7 "/„ ■ 



citrate (0.00125 N) 44.3 cm' 3.4 V„ 



citrate 45.7 cm' — 



I) These Proceedings. Vol. XV, p. 434. 



