]5(5 



ADVENTUBES IN RADIOISOTOPE RESEARCH 



that of the phosphoriis found in the faeces about 20 per cent was not 

 undigested material but was phosphorus which had already had a share 

 in building up the organism and had left it by entering the digestive 

 liquids and thus getting into the faeces. 



In the case above, 22.3 per cent of the radioactive P left through the 

 kidneys within 6 days and in other cases values varying between 20 

 and 25 per cent were obtained. 



Table 2. — Radioactive Phosphori s Injected 

 INTO the Blood of a Patient 



In carrying out experiments like those described above, the most 

 satisfactory procedure would be to replace by radioactive labelled 

 phosphorus atoms the normal phosphorus present in all the foodstuffs 

 administered. By bombarding the material in question with a strong 

 source of slow neutrons w^e could turn some of the phosphorus atoms 

 into radioactive phosphorus; but such a process always leads to a dis- 

 ruption of the molecular bonds of the phosphorus atoms which become 

 activated and so to a destruction of the chemical compound. We must 

 therefore content ourselves with adding inorganic radioactive phosphate 

 to the food consumed and try to obtain a mixture of radioactive inor- 

 ganic phosphate and food as uniform as possible. In our experiments 

 carried out with human suljjects the sodium radiophosphate was admi- 

 nistered in a large volume of milk. Milk contains 0.0795 per cent of 

 inorganic phosphorus and about half that amount (0.036 per cent) 



