NUTRITION LABORATORY. 193 



tainer to absorb the moisture given up to the air by the soda-lime. The air 

 is then returned to the subject for breathing, after replacing the oxygen ab- 

 sorbed by fresh oxygen from a cylinder of the gas. Inasmuch as the inspira- 

 tion of the dry air would be irritating to the nasal passage, provision is made 

 to moisten the air by passing it through a suitable vessel containing water. 

 Thus the subject breathes the air again and again, the carbon dioxide being 

 absorbed by the soda-lime, the water by the sulphuric acid, and the oxygen 

 supplied from the cylinder. The increase in weight of the soda-lime con- 

 tainer and the sulphuric-acid vessel indicates the amount of carbon dioxide 

 produced, and the loss in weight of the oxygen cylinder the amount of oxygen 

 absorbed. 



The apparatus has been most critically controlled by a series of tests in 

 which different weights of ether were burned inside of a small supplementary 

 chamber, and likewise it has a physiological control in that subjects have 

 alternately been tested in the respiration chamber, and also with the new 

 apparatus. The results given by the apparatus are highly satisfactory, and 

 it is now in constant use in connection with a series of observations on the 

 influence of the preceding diet upon the respiratory exchange. 



(8) The metabolism of man during the work of typewriting. Thorne M. Carpenter 

 and Francis G. Benedict. Jour. Biol. Chem. (6), in, p. 271. 1909. 



This article discusses in a tentative way the muscular work involved in 

 typewriting. It is of general interest in that a large number of people gain 

 their livelihood by typewriting, and the muscular work involved therein has 

 never been definitely studied. Two experiments were reported in which the 

 subjects remained inside of the calorimeter for a preliminary period without 

 typewriting, and then during a final period wrote on an average some 1,600 

 words per hour. While the results given are of a tentative nature and should 

 be amplified by further researches, they show that in general the metabolism 

 of man is increased 25 calories per hour by the work involved in typewriting 

 on a machine at the rate of i,6oo words per hour. 



