DOUGLAS METHOD. 67 



the clamp upon a burette standard. The latter has been of common 

 use in this laboratory, as all of the experiments made with this appa- 

 ratus have been with the subject lying upon a couch. With the bell 

 of the spirometer at zero, a reading is taken of the pointer, and the three- 

 way valve A is turned so that the expired air enters the spirometer 

 bell. The subject then breathes for a definite length of time, during 

 which period the air is collected in the spirometer. The valve is again 

 turned at the end of the experiment, a reading of the position of the 

 spirometer bell is made, records taken of the temperature and the 

 barometric pressure, and finally a sample of air is drawn from the 

 spirometer and analyzed. 



For the air analyses Tissot has used a special gas-analysis apparatus, 1 

 with a burette of about 100 c.c. capacity, in which he absorbs the 

 carbon dioxide over potash and the oxygen over phosphorus, or deter- 

 mines the oxygen by explosion with hydrogen. Personal experience 

 with this apparatus has shown that it is very complicated and difficult 

 to operate, and that it possesses no distinct advantage over the other 

 forms of gas-analysis apparatus used in this research. In connection 

 with the work on the Tissot method in this laboratory the accom- 

 panying gas analyses were almost exclusively made with the Haldane 

 gas-analysis apparatus subsequently described in this publication. 



DOUGLAS METHOD. 



The Douglas 2 method of determining the respiratory exchange is 

 of more recent origin than the other methods used in this investigation, 

 but it promises to be widely utilized because of its simplicity and the 

 portability of the apparatus required to make determinations of the 

 gaseous metabolism. In the researches of the Nutrition Laboratory 

 it has been employed by Mr. H. L. Higgins on a trip in the Alps. 3 

 During my visit to Oxford, Dr. Douglas demonstrated to me the tech- 

 nique of the method and subsequently gave me further information 

 regarding the details of the apparatus by correspondence and during 

 a visit to the Nutrition Laboratory. For these courtesies I wish to 

 express my thanks. 



The Douglas method may be briefly described as follows: The sub- 

 ject breathes through a mouthpiece by means of valves into a rubber 

 tube having an inside diameter of at least 20 mm. At a suitable 

 distance from the expiratory valve, a three-way valve of large bore is 

 attached which is connected with a wedge-shaped reservoir bag made 

 of rubber-lined cloth. The expired air collected in this bag is measured 

 at the end of the experiment by passing it through a meter and a 



Tissot, Trait6 de Physique Biologique, Paris, 1901, 1, p. 717. 



"Douglas, Journ. Physiol., 1911, 42; Proc. Physiol. Soc., p. xvii. Douglas, Haldane, Henderson, 

 and Schneider, Phil. Trans., 1913, 203, p. 217. 



3 Galeotti, Barkan, Giuliani, Higgins, Signorelli, Viale, Gli effetti dell'alcool sulla fatica in mon- 

 tagna. Reale Accademia dei Lincei, Rome, 1914, and Arch. d. Fisiol., 1914, 12, p. 277. 



