DIET, NUTRITION AND EXCRETION 61 



nitrate; the excess of silver nitrate used is determined by adding 

 standard solution of ammonium sulphocyanate in the presence of a 

 ferric salt. The Chinese excretes 5.27 grammes, the Tamil '5.21, 

 the Malay 8 and the Brahmin 6.34. An European excretes about 

 11 (Table I). On experimental diets individuals have been kept 

 in good conditions when the total content in sodium chloride is 

 reduced to 1 or 2 grammes per diem. Bunge has called attention 

 to the fact that among men and animals the desire for salt is 

 limited for the most part at least to those that use vegetable food. 

 The potassium salts of the vegetable food react with the sodium 

 chloride forming potassium chloride and a sodium salt, both of 

 which would be excreted by the kidney. The blood will thereby 

 lose some of its supply of sodium chloride, whence the craving for 

 more in the food (3). 



Urea. — The method employed calculates the amount of urea 

 by measuring the amount of nitrogen liberated from the urine by 

 sodium hypobromite. Doremus-Heinz ureometer is employed. 

 This method only gives approximate results. The Chinese excretes 

 16 grammes per diem, the Tamil 11.11, the Malay 13.35, the 

 Brahmin 11.08 whereas the average figure for an European is 35 

 (Table I). It is well known that the amount of urea depends 

 upon the amount of protein absorbed so that the greater the quan- 

 tity of absorbable protein in the diet the greater the quantity of 

 urea in the urine. About 80% of the total nitrogen in the urine 

 is excreted in the form of urea. 



Total Xitrogen. — This is estimated by Kjeldahl's method. 

 The Chinese excretes 9.25 grammes per diem, the Tamil 8.21, the 

 Malay 8.0, the Brahmin 6.61, the European figure being 16 (Table 

 I). It is considered accurate to take the nitrogen excretion as 

 an indicator of the amount of protein actually metabolised or used 

 by the body in performing its work. Since nitrogen forms about 

 16% of protein, the amount of nitrogen excreted multiplied by 

 6.25 gives the amount of protein metabolised. The figures thus 

 obtained are 57.8 grammes of protein for the Chinese, 51.5 for the 

 Tamil, 50 for the Malay, 11.5 for the Brahmin and 100 for the 

 European. We have seen that the Brahmin eats a good deal more 

 protein than the other Asiatics (Table II), nevertheless he uses a 

 smaller amount in metabolism, so that evidently a smaller propor- 

 tion of the protein of his food is absorbed. This is due to its bulk 

 and its in digestibility. 



Ammonia Coefficient. — This is the amount of nitrogen, ex- 

 creted as ammonia, expressed in terms of percentage of the total 

 nitrogen. In an European it is 3.6%, in the Chinese student 5.4%, 

 in the Tamil 6.3%, in the Malay 6.8%, and in the Brahmin 7.1% 

 (Table I). It is higher in the Asiatics than in the European 

 because the protein intake is greatly reduced in the Asiatics so 

 that there is a low total nitrogen excretion. Of the Asiatics the 

 Brahmin has the highest coefficient because he excretes the smallest 



R. A. Soc, No. 76, 1917. 



