378 DISCOVERY REPORTS 



In a few cases the solubility of air nitrogen in the urine at atmospheric pressure was 

 estimated at various temperatures. The procedure consisted in shaking the urine in a 

 flask open to the air with a thermometer dipping in the Hquid, the whole operation being 

 performed in a water bath. The urine was pipetted ofl^ and introduced into the gas 

 burette in the usual way. In order to form a standard of comparison, the technique was 

 as far as possible the same as in treating the sample originally. As will be seen from the 

 figures in column 3, Table I, the solubility of nitrogen in whale urine is low both at 

 36° C. and at room temperature. Hill quotes two figures for normal nitrogen content 

 in human urine at atmospheric pressure, 1-14 and 0-90 vol. per cent, of which he prefers 

 the latter. The corresponding figure for whale urine is o-6o vol. per cent. Whale urine 

 contains more salt than human urine, which should not have much eff'ect on the solu- 

 bility of a gas ; but whale urine also contains considerable quantities of protein. ^ Every 

 sample produced a thick precipitate when boiled ; a few samples were estimated gravi- 

 metrically and an average of 7 g./iooo cc. was obtained. It was apparent from the 

 appearance of many samples which were boiled that the protein content varied con- 

 siderably, reaching in one case (no. 56) 30 g./iooo cc. The eff'ect of protein would 

 be to reduce the solubility of gases in the liquid, but there may be other reasons for the 

 low figures obtained. The technique of estimating the solubility was the same as that of 

 estimating the original gas content, and the results can therefore be taken to be relative. 

 The conclusion is then that the urine is supersaturated with nitrogen in some cases and 

 not in others, though the balance is in favour of supersaturation of a low order. The 

 average content of forty-one samples was 073 vol. per cent, while the solubility was 

 0-62 at the temperature of the living whale. The issue may have been clouded by the 

 presence of numerous small organisms in the urine, further reference to which will be 

 made in dealing with blood. 



The carbon dioxide content of the urine is of interest. In column 4, Table I, some 

 large volumes of total carbon dioxide are recorded in fresh urines ; considerable variation 

 is shown, and there is also a variation in the amount of combined carbon dioxide present 

 in those samples which were estimated. Large amounts of combined carbon dioxide are 

 rare and probably have no connection with the balance of respiratory gases. Specimens 

 20 and 56 had large combined carbon dioxide, especially no. 56, which is an exceptional 

 specimen in several other ways — high specific gravity, very low salinity, and very high 

 protein. 



Control experiments were made with human urine, which was treated in exactly the 

 same way. Variable results were obtained from the same subject, and the dissolved 

 carbon dioxide ranged from 1-24 to 5-40 vol. per cent. The combined carbon dioxide 

 was below i-o vol. per cent. 



In Fig. I the volumes of carbon dioxide found in whales' urine have been arranged 

 along a line which represents the solubihty graph of water at 36° C. Each volume found 



1 A number of specimens were examined under the microscope and found to contain millions of organisms 

 identical in appearance with those referred to in the section on blood. It is possible that these organisms 

 are excreted through the kidneys. 



