228 Oogch ajn>$ Kobayashi 1)<I< rmiiiation of 



of thorium nitrate and the mixtures were allowed to stand 

 on the steam bath for intervals varying from fifteen to 

 thirty minutes. The precipitated oxalate was filtered off 

 on asbestos in the perforated crucible and washed with 

 cold water containing in every "J.") cm 3 a drop of concern- 

 ed sulphuric acid. The oxalic acid in the filtrate and 

 the thorium oxalate of the precipitate were oxidized sep- 

 arately, by the standard permanganate. In the former 

 ease the amount of permanganate measured directly the 

 oxalic acid radical of precipitated oxalate; in the latter 

 case the amount of permanganate used measured that 

 part of the known amount of standard oxalic acid which 

 remained uncombined, the difference between the amount 

 of oxalic acid taken and that found in the filtrate repre- 

 senting also the combined oxalic acid radical. 



In the treatment of the precipitate, the crucible and 

 precipitate were put into a beaker containing 100 cm 3 of 

 water, the whole was heated to a temperature of about 

 85°, sulphuric acid (5 cm 3 of the 1:1 acid) added, the 

 measured permanganate solution run in until the larger 

 part of the precipitate had been oxidized, the mixture 

 again heated to. facilitate the oxidation of the precipi- 

 tate (retained by the cooling of the mixture during the 

 titration) and the - titration continued to an end-point 

 (which is very sharp if the liquid is kept hot). The 

 coloration was matched with that obtained by adding a 

 definite amount of N/10 permanganate (0-02 cm 3 to 

 0-04 cm 3 ) to an emulsion of asbestos in 100 cm 3 of water. 



The filtrate from the precipitated thorium oxalate was 

 diluted to a volume of 200 cm 3 , heated to about 85°, and 

 sulphuric acid (10 cm 3 of the 1:1 acid) was added. The 

 titration with permanganate was continued to the end- 

 point, since in the titration of the soluble oxalic acid in 

 the filtrate there is no need of reheating as is the case in 

 the titration of the insoluble oxalate. 



In the experiments of Series I, A, in which the oxalic- 

 acid was added to the hot solution of thorium nitrate, 

 the results show a deficiency amounting in the average to 

 2-75 r /c of the oxalate radical which should be in com- 

 bination with thorium, upon the hypothesis that the pre- 

 cipitate is the normal oxalate Th(C ? 4 ) 2 . 



The results of the experiments in Series I, B, in which 

 the oxalic acid was added to the cold solution of the 

 thorium salt, though more regular, point to a deviation of 



