1912.] B. cloacae (Jordan) on Citric and Malic Acids. 3 



receiver (d) being slightly lowered to create a partial vacuum in the burette 

 tube (a). At intervals of 24 hours, the air in the burette (b) is swept 

 through the apparatus into the burette (a) through the tube (m) by raising 

 the receiver (e) and simultaneously lowering the receiver (d). Then, by 

 reversing the taps, it is returned to the burette (5) through the tube (c). 



By thrice repeating these manipulations, the carbon dioxide produced by 

 the growth of the organism in the medium is removed from the tube (/), 

 and absorbed by the caustic potash solution in (g). At the conclusion of the 

 experiment, indicated by the non-diminution of the volume of air in (b), the 

 flask (g) is disconnected, and the carbon dioxide determined by double 

 titration with N/IO H 2 S0 4 , using phenolphthalein and methyl orange as 

 indicators. The experiments were carried out at an approximate tem- 

 perature of 37°. 



It is essential that the burette taps be perfectly gas-tight. The form 

 shown in the diagram was found to be the most satisfactory and the taps 

 used were tested against a vacuum. As a lute, resin ointment proved to be 

 the best for a temperature of 37°. 



In making the readings, of which the initial and final are, of course, all 

 important, it is essential to be quite sure that no marked alteration of 

 temperature has taken place previous to observation. To obviate any error 

 from this source, three readings were made in each case at intervals of 

 30 minutes, and their agreement showed that the experiment was being 

 satisfactorily carried out. 



To test the apparatus, a blank experiment was made, 10 c.c. of water being 

 placed in the tube (/). 



Internal capacity of apparatus = 176"8 c.c. 





Burette 

 reading. 



Temperature. 



Barometer 

 reading. 



Volume of air 

 at N.T.P. 



June 17, 12.30 p.m 



2.30 „ 



5.0 , 



„ 19, 10.30 a.m 



The door of the hot room was 

 ris 



3.0 p.m 



c.c. 

 83 -2 

 83-0 

 83 -0 



82 -8 



allowed to rema 

 ing quickly on a 



80 -2 



83 -0 







37 -6 

 37 -4 

 37 -4 

 37 -8 



in open for 5 mi 

 gain closing the 



35 -4 

 37 -6 



mm. c.c. 



756 -6 213 -0 



757 -0 213 -2 



757 1 213 -2 



758 -7 213 -0 



lutes. Fall in temperature 4 '2°, 

 loor. 



758 -7 214 -3 

 757 -6 213 -1 



From this test it is seen that the apparatus described is quite satisfactory, 

 provided that due precaution is taken that the burette readings are made 

 while the apparatus is not subject to fluctuations of temperature. 



B 2 



