466 ADVENTURES IN RADIOISOTOPE RESEARCH 



of the latter converted into water, and the density of this deter- 

 mined. The preparation of water from the oxygen of the sulphate 

 was carried out in the following way. The barium sulphate preci- 

 pitate was dried at 400° ('. in a stream of nitrogen and then reduced 

 with purified carbon at 900° C. ; the gases evolved were mixed with a 

 great excess of hydrogen and stored over oil in a gasometer ; and, 

 finally, the gas mixture was led over a nickel catalyst at 310° C. and 

 the water formed collected. The density determination was kindly 

 carried out by Mr. O. Jacobsen, using Linderstrom-Lang's floating-drop 

 method. 



Should the sulphate oxygen, during its stay in the animal, enter into 

 exchange reactions with other oxygen atoms present in very great 

 excess in the body, the oxygen of the heavy radicals would be replaced by 

 normal oxygen atoms and the water prepared from the sulphate re- 

 covered from the urine would show the density of normal water. If, on 

 the other hand, the sulphate ions injected retain the oxygen atom 

 with which they start, the water prepared from the urine sulphate 

 should show an excess density of 370 parts per million if no secretion 

 of normal sulphate took place. The water prepared from the sulphate 

 isolated from the urine after injecting heavy-oxygen sulphate has shown 

 a very appreciable density excess — 240 parts per million. When com- 

 paring this value with the one calculated on the assumption that no 

 exchange of sulphate oxygen took place, we must consider the following 

 fact. Besides the heavy-oxygen sulphate — 0.84 gm of sodium sulphate 

 being secreted in all during the day following injection — the urine 

 contains also sulphate, even when no injection is given, the amount 

 of which we found to correspond to 0.23 gm per day. The latter is 

 normal sulphate and its presence reduces the density excess of the 

 water prepared from the urine sulphate. 



From the high density found for the water prepared from urine sul- 

 phate, one must conclude that most of the individual sulphate ions 

 injected into the rabbit are recovered in their original form, and from 

 this it follows that at least the greatest part of the sulphate administered 

 leaves the body unchanged. 



References 



1. Blxjmenthal and Herbebt, Trans. Faraday Soc. 38, 849 (1937) 



2. S. C. Datta, J. N. E. Day and C. K. Ingold, J. Chem. Soc. 1968 (1937). 



3. HuFFMANN and Ubey, Ind. Eng. Chem. 29, 531 (1937) 



4. Manian, Ubey and Bleakney, J. Amer. Chem. Soc. 56, 2601 (1934) 



