24 August Krogh and Marie Krogh. 



Certain food stuffs the composition of which is very constant 

 viz. sugar, butter, alcohol and coffee were not included in the dayly 

 samples, but special samples were preserved for analysis and the quan- 

 tities given weighed each time. 



The samples of food have been analysed in the Nutrition Labora- 

 tory. "The partially dried material was ground as best could be in 

 a small hand mill, but it was necessary in some samples to pulverize 

 as finely as possible in the mortar. The sticky, gluey nature of some 

 of the materials made this very difficult and the excessive amount of 

 fat in certain of the foods made it difficult to secure a fair composite 

 sample. Every precaution was taken however to secure as even 

 a sample as possible in taking out the portions for weighing for 

 analysis. 



The analyses were made on the partially dried basis and then 

 computed on to the fresh weight as determined in Greenland. Deter- 

 minations were made of nitrogen, heat of combustion and crude fat 

 (ether extract). The crude fat determinations are of course much 

 less reliable than the determinations of nitrogen and heat of com- 

 bustion". 



From the analytical data a table (p. 27) has been compiled showing 

 the quantities of the separate food stuffs for each day and the corre- 

 sponding amount of nitrogen, fat and available energy. As the energy 

 of the urine has been determined on a few samples only we have de- 

 duced 10 Calories per gr. nitrogen in order to obtain the available 

 energy of the nitrogenous substances. The accuracy of the final energy 

 values is of course comparatively small. 



We could not induce our subjects to void urine at prescribed 

 intervals which would have simplified the calculations a great deal 

 but it was fortunate that they almost invariably did it simultane- 

 ously. The quantities were each time measured accurately and samples 

 of at least |4 the volume were preserved in medicine bottles the corks 

 of which were soaked in paraffin wax. To these were added about 

 1 volume %o of the commercial 40 "/o solution of formaldehyde. We 

 experienced at first some difficulties from the growth of moulds in 

 the urine samples, but heating to about 60° in stoppered bottles did 

 away with this. The samples were analysed in the Nutrition Labora- 

 tory. Nitrogen determinations were made on all of them and on some 

 the heat of combustion was also determined after drying in vacuo 

 at ordinary temperature. A number of the samples sent were distri- 

 buted on two bottles labelled a and b. These were analysed as separate 

 samples. The discrepancies are extremely small, ranging from to 

 0.05 gr. N in the whole quantity of urine, which shows both that the 

 analyses have been very accurately made and also that the preserva- 

 tion has had either a constant effect or no effect at all upon the ni- 

 trogen percentage. 



