OPTICAL-LEVER RESPIROMETKY 



401 



this writing production of the instrument has not yet been resumed. 

 The apparatus is rather complicated, mechanically, and since there 

 are other more available instruments which have simpler construc- 

 tion and greater sensitivity the use of the optical-lever manometer 

 will probably be limited. Therefore, only a cursory description of 

 the apparatus will be given. 



Fig. 140. Details of revolving frame. 

 From Heatley (1940) 



The respiration chamber (Fig. 137) consists of a "cup" which is 

 a 25 mm. square of glass, 3-4 mm. thick, in which cavities are 

 ground and then coated with a paraffin film. Drops placed in these 



