162 



Scientific Proceedings (120). 



The compound crystallizes from water, dilute alcohol and 

 dilute acetone, in shining white microscopic plates or rosettes of 

 rather indefinite crystal form. As a criterion of puiity, amino 

 nitrogen determinations were carried out aftei successive crystalli- 

 zations until constant values were obtained. At this time the 

 proportion of N to S was 2:1, and it w T as assumed that the prep- 

 aration was pure. Analyses of this product indicated the 

 formula C11H23SN2O4. Unfortunately, when most of the amino 

 acid had been used up, it was found that the remaining material 

 contained as an impurity a substance forming a hydrochloride 

 relatively insoluble in concentrated HC1. Since the entire prep- 

 aration had not been crystallized at the same time, and only the 

 first portions, used for quantitative analyses, had been checked 

 up by amino nitrogen and sulphur determinations, it is possible 

 that the impurity was not present in the material which was 

 analyzed. From the few tenths of a gram remaining, the insoluble 

 hydrochloiide was removed as completely as possible by dissolving 

 in boiling HC1 and allowing to crystallize on ice for several days. 

 The filtrate, containing the sulphur compound, was freed from 

 HC1 by evaporation and by Ag 2 S0 4 , and the sparingly soluble 

 copper salt prepared by boiling the solution with Cu(OH) 2 and 

 filtering. The salt separates as microscopic, pale blue platelets. 

 About 0.25 gram of this salt was obtained, and a single combustion 

 and amino nitrogen determination gave the formula CnH 2 i- 

 SN 2 O^Cu, corresponding exactly with that obtained foi the amino 

 acid in the earlier analyses. The combustion was done by the 

 Dennstedt method, permitting the simultaneous determination 

 of carbon, hydrogen, sulphur and copper. 



The nitrogens are both in the form of amino groups, and since 

 the solution of the compound in water is practically neutral, it is 

 probable that two COOH groups are present. A single formol 

 titration gave results which were slightly low, but in fair con- 

 formity with this supposition. The sulphur is not in the lead- 

 blackening form, and is not readily split off as sulphate by boiling 

 with acids or alkalis." The number of hydrogen atoms present 

 suggests a straight chain compound, but no direct evidence of the 

 structure has been obtained. 



In order to rule out the possibility of the mateiial used for 

 analyses having been impure, it is planned to prepare another lot 



