578 



üt' the purified doses the quanta iiiusi he much larger: 

 Minimum-doses of the purified preparations. 



Tlie iiiininHini-, optimum-, and higiiest practicable doses are for 

 the purified preparations of caesium in milligrammes of caesium- 

 chloride per Liter, on an average in the ratios of: 



1678 : 2760 : 4134. 



min. opt. highest pract. 



When comparing impure and pure caesium we obtained the 

 following mean results: 



Impure CsCl 



Pure CsCl 



in minimo 

 in optimo 

 highest pract. 



5.5 X min. KCl 

 1 1 X >■ ., 



10.7 X min. KCl 

 n-1 X „ „ 

 26.5 X „ „ 



So we see that in minimo the quantity of pure caesium must 

 be from 2 to 3 times larger than that of impure caesium. 



On the 16^'i of May 1923 it appeared that of the preparation, 

 purified to such a degree that no radiation whatever could be 

 demonstrated for a given heart, in minimo 39, in optimo 47 and 

 as highest practicable dosis 58 grs. had to be added per Liter of 

 circulating fluid. It is obvious that in such cases the quantities of 

 NaCl had to be largely diminished in order to prevent hjper-isotonia. 



One of us has set up for the radio-active substitutes of potassium 

 a working-hypothesis, viz. that in general isolated organs require 

 so mucii of a radio-active element in their physiological circulating 

 liquid as is necessary to generate per second the emission of a 

 number of ions that is equal for all substitutes. This hypothesis can 

 be expressed in a logarithmic graph. 



In such a grapii rubidium and caesium cannot be taken up directly, 

 since we do not know how many ions these substances emit per 



