J32 "^- Lindhard. 



As will be seen, these results agree well with the English. 



In this country Hasselbalch has briefly discussed the alveolar 

 carbonic acid tension in his work on the chemical light-bath'. He 

 puts forward the hypothesis, that the chemical light-bath may 

 increase the percentage of carbonic acid in the alveolar air, and the 

 results given are apparently in favour of this view; but only appar- 

 ently. If we study his Table II closely, it is seen that the series is 

 irregular, but not that it shows an increase in the percentage of 

 carbonic acid after the light-baths. The average of the series is 

 4"47. The first 9 values, thus about the first third of the series, all 

 have negative deviations from the average; on the 10th day, in the 

 morning before a light-bath, the carbonic acid percentage suddenly 

 rises simultaneously with a rise of 2 degrees in the temperature of 

 the room. In the following period, almost the second third of the 

 series, the distribution seems more according to chance, the fluc- 

 tuations being small and distributed on both sides of the average 

 (calculating with 2 decimals instead of with one would certainly 

 give a more regular series); but after 14' light-bath the value sud- 

 denly rises and we now have a series of large, positive deviations; 

 at the same time the temperature in the room again rises. When 

 we consider that no rise can be seen after the first light-baths, and 

 just as little after the light-baths in Table III, we may well conclude 

 that special conditions have been operative after the 14' light-bath^. 

 What these conditions may be does not appear from the table. The 

 connection indicated with the air-temperature cannot be the deter- 

 minating influence; both in Haldane's and my own investigations 

 temperature variations such as those in question here produce quite 

 the opposite movement in the carbonic acid contents of the alveolar 

 air. But it is not excluded that changes in the air-pressure may 

 occur at the same time, which would explain the phenomenon. A 

 second factor, which must be taken into consideration after Hal- 

 dane's investigations, is the blood-pressure; but there is no infor- 

 mation about this point in these last experiments. A remark to 

 experiment 45, noting a painful reaction on the face, leads one to 

 think of the last-named possibility. Lastly, it must be remembered, 

 that it is the percentage of carbonic acid, not the tension, which is 

 given; the recalculation of the series in terms of mercury pressure 

 would certainly make some change. 



1 Hospitalstidende Nos. 45, 46, 47, 1905. 



' According to conversation with Hasselbalch, two longer experimental series on 

 a different individual have not been successful in showing any support for the 

 view, that the alveolar carbonic tension rises after the light-bath. It seems 

 quite uninfluenced by the latter. 



