NUTRITION LABORATORY. 187 



surface. It is hoped by this means to obtain some information upon the 

 question as to whether a change in temperature in one portion of the body 

 is accompanied by a similar change in another portion, a question of funda- 

 mental importance in experiments on heat production. 



HEAT OF COMBUSTION OF ORGANIC COMPOUNDS. 



Considerable attention has been given during the past year to the deter- 

 mination of the heat of combustion of a number of organic compounds, par- 

 ticularly those which are very important in investigations in physiological 

 chemistry. The adiabatic bomb calorimeter previously mentioned was used 

 for this work and the most time was given to the determinations of the heat 

 of combustion of ethyl alcohol. Ordinary alcohol was used, i. e., about 90 

 per cent, in gelatine capsules, and also in glass bulbs according to the method 

 described by Richards. This alcohol has also been diluted in varying pro- 

 portions, and accurate determinations made of the heat of combustion. In 

 addition to the work on alcohol, some preliminary determinations have been 

 made of the heat of combustion of acetone, lactic acid, and some foods. It 

 is expected to continue this work in connection with other work in the labo- 

 ratory. 



ANALYSES OF DIABETIC FOODS. 



In connection with the study of diabetes carried on in cooperation with 

 Dr. E. P. Joslin, a number of diabetic foods, so-called, have been collected 

 and analyzed. Many of these foods are especially advertised as being excel- 

 lent for the use of diabetics, and accordingly particular attention has been 

 paid to the determination of the total carbohydrate content. A great variety 

 of foods was analyzed, not only breads, but also sugarless milk, sugarless 

 jelly, chocolate, vegetables of various kinds, and other materials recom- 

 mended for diabetics. The analyses of these foods have proved of great 

 value in connection with the treatment of diabetics, as such foods were some- 

 times found to contain more carbohydrates than stated. They could thus be 

 eliminated from the diet of a patient and the ingestion of carbohydrate prop- 

 erly controlled. 



NUTRITIVE VALUE OF SERVINGS OF FOOD. 



The average individual has little, if any, conception of the amount of nutri- 

 ment in food, and when we attempt to estimate the energy in a single meal, 

 or, indeed, in a single helping of food, we find that it is very difficult to 

 obtain any very accurate idea of the amount. Most people, including many 

 considered to be experts, when given the number of materials in a meal and 

 an approximate idea of the size of the helpings, are unable to tell how much 

 energy the materials should supply. When the weight and heat of combus- 

 tion of a material are known, the amount of energy can be calculated very 

 closely, but very few people are in a position to weigh every helping during 

 the meal or to know the heat of combustion of the different materials used 

 or the amount of protein contained in them. 



