120 W. M. Wallace, W. B. Weil and A. Taylor 



indicated that its nitrogen content multiplied by 6-25 plus 

 the weight of its ash very closely approximated 100 per cent 

 of the material. Consequently, fat has been calculated in all 

 of the data by the relation: Fat = dead weight— water 

 weight— (nitrogen X6-254- ash weight). All of the constitu- 

 ents shown in Table II have been calculated as g., m-mole or 

 m-equiv. per 100 g. of protein plus ash (i.e. fat-free dry solids). 



Ash. A sample of carcass powder was weighed after in- 

 cineration at 600° in platinum. 



Nitrogen. Determined by macro-Kjeldahl analysis using 

 selenium as a catalyst. 



Chloride. A micro modification of the method of Lowry and 

 Hastings (1942) was used with cold nitric acid filtrates. 

 Samples of the homogenized powder were also analysed 

 polarographically for chloride, using sulphuric acid filtrates, 

 with excellent agreement between the two methods. 



Sodium, Potassium and Calcium. These were determined on 

 the ash after separation of calcium using methods previously 

 described (Bergstrom and Wallace, 1954). 



Magnesium. Determinations were done on the ash using the 

 method of Fister (1950). 



Phosphorus. This was determined on the ash by the method 

 of Fiske and Subbarow (1925). 



All electrolyte and nitrogen analyses were in duplicate. 



Results 



The analytical data obtained in the experiments are shown 

 in Table II. For comparative purposes the whole body 

 analyses on the albino rat of Light and co-workers (1934) and 

 of Cheek and West (1956) are included. Also shown are the 

 average data of Widdowson and Spray (195 IB) for six normal 

 human newborn babies and the data for single whole adult 

 human bodies of Widdowson, McCance and Spray (1951^), 

 Forbes, Cooper and Mitchell (1953) and Mitchell and co- 

 workers (1945). The data for water, protein and ash have been 

 calculated per kilogram of fat-free body weight. The water 

 and electrolytes are also shown using as a reference standard 



