NUTRITION LABORATORY. 195 



measured by the respiratory exchang-e and the heat elimination was deter- 

 mined with the subjects at rest and when typewriting, the work period fol- 

 lowing immediately the rest period. Duplicate experiments were made with 

 3 of the subjects. It was found that the typewriting at rates from 57 to 115 

 words per minute resulted in increasing the metabolism above that of rest 

 from 30 to 70 per cent, while the increase in the energy output per 1,000 

 words was about 7 calories, and the increase in the carbon dioxide and the 

 oxygen was about 2.5 grams. Considered on the basis of 1,000 strokes, there 

 was an increase of 1.6 calories of energy^ and 0.57 and 0.54 gram of carbon 

 dioxide and oxygen respectively. In the experiments in which the increase 

 was measured by periods, it was found that there was a gradual decrease in 

 energy expenditure per 1,000 strokes, which was most marked with those 

 subjects whose fingers became fatigued. The variation in the increase in 

 metabolism for the different subjects was considered to be due to the differ- 

 ence in individual facility and technique. 



(7) Some energy factors of the urine excreted after severe muscular exercise. Harold 



L. Higgins and Francis G. Benedict. Amer. Jour. Physiol., 28, p. 291. 1911. 



The determinations of carbon and energy in urine, always of great im- 

 portance in total metabolism experiments, have become of added interest in 

 recent years in that the relationships of the total nitrogen, carbon, and energy 

 in the urine, i. e., the carbon-nitrogen and the calorie-nitrogen ratios, have 

 acquired a pathological significance. By a study of these ratios, a perturbed 

 metabolism may be easily detected and much information secured with regard 

 to its character, since under such conditions there are almost invariably 

 present in the urine intermediate metabolic products which contain consider- 

 able amounts of carbon, and relatively small amounts, if any, of nitrogen, 

 thus increasing the carbon-nitrogen and calorie-nitrogen ratios. The use of 

 these ratios for detecting and studying cases of perturbed metabolism not 

 only does away with the necessity for an elaborate estimation of amino-acids, 

 purine derivatives, etc., but is of especial value when the volume of urine is 

 too small to admit of tests for these products. In a study made of urines 

 excreted immediately following an exhaustive running race, these ratios 

 were used to find whether or not a perturbed metabolism resulted from the 

 severe muscular exercise. Some 18 urines were studied, and the results are 

 presented in this paper. The values for 12 out of the 18 urines were normal ; 

 the remaining 6 urines gave high ratios which were probably due to per- 

 verted protein metabolism. The method used for the determination of the 

 heats of combustion is given in some detail, and in view of the fact that the 

 calorie-carbon ratio is constant, the advantage is pointed out of the develop- 

 ment of either a volumetric method or a wet process by which determinations 

 of carbon in urine can be simply, quickly, and accurately made. The paper 

 also includes a brief review of previous study of the carbon-nitrogen and 

 calorie-nitrogen ratios. 



(8) The heat of combustion of compounds of physiological importance. Albert G. 



Emery and Francis G. Benedict. Amer. Jour. Physiol., 28, p. 301. 191 1. 



The researches conducted at the Nutrition Laboratory on the metabolism 

 of matter and energy in the human body brought out the desirability of more 

 specific information regarding the heat of combustion of many organic com- 

 pounds of physiological importance. Accordingly, specimens of a consider- 

 able number of these compounds were obtained with as high a degree of 

 purity as possible, and the heats of combustion determined. For these deter- 

 minations, an exceedingly exact adiabatic calorimeter was used, of which the 



