NUTRITION LABORATORY. 



225 



important role or to determine in any degree the marked rise in metabolism 

 so frequently noted after the ingestion of various food materials. 



(3) The influence on the respiratory exchange of varying amounts of carbohydrate in 



the diet. Francis G. Benedict and Harold L. Higgins. Amer. Jour. Physiol., 

 30, p. 217. 1912. 



The character and amount of body metabolism before food is consumed 

 in the morning (i. e., after active digestion has ceased) is dependent to large 

 extent upon the character and amount of the diet on the preceding day. 

 This paper gives the results of a study of the effect on the respiratory ex- 

 change of variations in the carbohydrate content of the diet of the preceding 

 day. It was observed that the same diet, with the same individual, always 

 led to essentially the same respiratory exchange the next morning before 

 food was taken; also with different normal individuals the same diet led to 

 essentially the same respiratory quotient, showing that similar body material 

 w^s being metabolized. Daily diets were calculated having a constant pro- 

 tein content (105 grams) and a constant energy value (3,000 calories) but 

 varying amounts of carbohydrates (100, 125, 200, 400, and 600 grams re- 

 spectively), the fat content being regulated to make the required energy 

 content of the diet. A carbohydrate-free diet was also used. The average 

 respiratory quotients following diets with varying amounts of carbohydrates 

 are given in the table. 



When little or no carbohydrate had been taken, 

 the respiratory quotient is seen to approximate con- 

 ditions indicating the combustion of pure fat (res- 

 piratory quotient 0.71), while with larger amounts 

 of carbohydrates in the diet the respiratory quotient 

 was nearer that for carbohydrates alone (respiratory 

 quotient i.oo). The conclusion is drawn that the 

 supply of body carbohydrate bore a distinct relation 

 to the quantity of carbohydrate in the preceding 

 diet. For determining the respiratory metabolism, 

 use was made of the small respiration apparatus devised in this laboratory. 



(4) The sources of error and the electrolytic standardization of the conditions of the 



iodide method of copper analysis. Amos W. Peters. Jour. Amer. Chem. Soc, 

 34, p. 422. 1912. 



The conditions were determined for the standardization and use of so- 

 dium thiosulphate when intended for the measurement of copper, especially 

 in sugar analyses. A method was devised for the rapid electrolytic deposi- 

 tion of copper by simple means with the use of a tartrate-cyanide electro- 

 lyte ; also a general method for the preparation of solutions of metallic cop- 

 per or of its compounds for the iodide method. It was shown that the 

 results by the iodide method are affected by varying concentrations of min- 

 eral acid and by the presence of salts with or w^ithout acetic or mineral 

 acid, and how these effects can be compensated quantitatively. The con- 

 ditions of accuracy of the iodide method were determined for both sugar 

 analysis and for general purposes. 



(5) A critical study of sugar analysis by copper reduction methods. Amos W. Peters. 



Jour. Amer. Chem. Soc, 34, p. 928. 1912. 



This paper, which embodies the examination of the iodide method of cop- 

 per analysis elaborated in the previous paper, involves a study of the various 



