190 PROCEEDINGS OF THE AMERICAN ACADEMY 



In the preparation of the sparingly soluble barium salt, we used 

 five or six molecules of baric hydrate to one of mucobromic acid. 

 When the reaction appeared at an end, we precipitated the excess of 

 baric hydrate with carbonic dioxide, and evaporated the filtered solu- 

 tion to a small volume. When this solution was slowly evaporated 

 upon the water bath, we found, in accordance with the statements of 

 Schmelz and Beilstein, that the salt separated in thin crusts which 

 had no visible crystalline structure. If, however, the solution was 

 boiled down rapidly over the lamp, at a certain point the salt suddenly 

 separated in fine, silky needles, which were still further increased as 

 the solution cooled. These crystals were well washed with cold 

 water, redissolved in boiling water, and precipitated with plumbic 

 acetate. In this way a granular lead salt was thrown down, which, 

 when examined under the microscope, was seen to consist of well- 

 formed rhombic plates. For analysis, the salt was dried at 110°. 



I. 0.5939 grm. substance gave 0.2434 grm. COj and 0.0470 grm. of 



H,0. 



II. 0.3459 grm. gave, by ignition with H^SO^, 0.3402 grm. PbSO^. 



Calculated for PbCiOj. Calculated for PbCsHjO^. Found. 



I. n. 



C 15.84 11.65 11.18 



H 0.65 0.88 



Pb 68.32 66.99 67.22 



It will be seen that the percentages found correspond closely with 

 those required by plumbic malonate, and differ widely from those re- 

 quired by the formula of Schmelz and Beilstein. 



The barium salt also agrees well with the description of baric 

 malonate given by Heintzel * and Finkelstein.f The analyses we have 

 made of the salt have given us too high a percentage of barium, 

 although materially lower than that found by Schmelz and Beilstein. 



I. 0.5212 grm. of the salt, dried at 120°, gave 0.5214 grm. BaSO,. 



II. 0.3455 grm. of the salt, dried at 100°, gave 0.3159 grm. BaSO,. 



III. 0.2139 grm. of the salt, dried at 100°, gave 0.1956 grm. BaSO<. 



Calculated for BaC3Hj04.H,0. Found. 



I. 11. III. Schmelz and Beilstein 



Ba 53.33 54.70 53.75 53.73 56.32 



* Ann. Chem. u. Pliarm., cxxix. 133. 

 t Ann. Clicm. u. riarm., cxxxiii. 343. 



