Drushel — Estimation of Potassium in Animal Fluids. 555 



Art. LII. — The Volumetric Estimation of Potassium in 

 Animal Fluids ; by W. A. Djrushel. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — cxcii.] 



The distribution of potassium' in plant and animal tissues 

 has been studied by Macallum* and others. Macallum pre- 

 cipitated potassium in place as potassium sodium cobalti-nitrite, 

 an insoluble potassium salt which by its crystalline form and 

 color is easily recognizable under the microscope. To study 

 the function of potassium in the animal organism it is desirable 

 to have a simple and rapid method for its estimation in the 

 various tissues and fluids. A number of quantitative methods 

 have been proposed which, however, are not wholly free from 

 objections. 



M. Kretschy. m 1 876, after having . carefully studied the 

 several indirect methods for potassium and sodium in the 

 presence of each other, finally adopted a modification of the 

 chlorplatinate method for potassium in the presence of rela- 

 tively large amounts of sodium in physiological work. He 

 worked with quantities of potassium ranging from 3 mgrm. to 

 120 mgrm., precipitating it as the chlorplatinate in the usual 

 manner. The washed and dried precipitate was carefully 

 ignited, the residue extracted with water and the extract evapor- 

 ated to dryness. This residue was gently ignited and weighed 

 as potassium chloride. A small amount of platinum usually 

 passed through the filter, giving a result which was too high 

 for potassium chloride. To avoid error on this account the 

 weighed potassium chloride was dissolved in water, any residue 

 of platinum filtered off on ashless paper, ignited and weighed, 

 and the necessary correction made in the weight of the potas- 

 sium chloride. 



Some years later Lehmann, f Bunge,;}: Heintz,§ and Pribram 

 and Gregor|| used different modifications of the Fresenius chlor- 

 platinate method for the estimation of potassium in urine. In 

 the methods of Lehmann, Bunge, and Pribram and Gregor the 

 sulphate radical was removed by an excess of barium hydrox- 

 ide or barium chloride ;. subsequently the excess of barium was 

 removed by ammonium carbonate and ammonium hydroxide, 

 or in case of barium hydroxide by carbon dioxide. Lehmann 

 evaporated .the urine with ammonium sulphate before ashing 

 the residue, while Bunge treated the urine directly with bar- 

 ium hydroxide. Pribram and Gregor oxidized the organic 

 matter by heating the urine, acidified with sulphuric acid, to 



* Jour, of Physiol., xxxii, 95 (London). f Zeitschr. physiol. Chem., viii, 508. 

 % Zeitschr. Biologie, ix, 139. §Pogg. Ann., lxvi, 133. 



|| Zeitschr. anal. Chem., xxxviii, 409. 



