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Lewis Knudson 



few inches of the bottom of the flask. The upper part of the glass tube 

 was bent at a right angle, and attached to it was a U-tube filled with 

 cotton. The side tube of the culture vessel was similarly provided with a 

 U-tube. The culture chamber, with the U-tube, was connected on one 

 side with a Friedrich gas-washing bottle containing a solution of potas- 

 sium hydroxide (KOH) of a specific gravitj^ of 1.27. This gas-washing 

 bottle was in turn connected with a large 10-liter aspirator bottle, from 

 which a large glass tube passed out of doors, whence the air was obtained. 

 The side tube of the culture vessel was connected by means of the U-tube 

 and glass and rubber tubing with a calcium chloride tower, which in 



Fig. 8. respiration apparatus, showing arrangement of whole 



turn was connected with a potash bulb ha\'ing a small calcium chloride 

 tube attached. Finallj^, the potash bull) was connected with a safety 

 gas-washing bottle, and this bottle was connected with a Hichard's pump. 

 All the usual technical precautions were observed in fitting the respira- 

 tion apparatus, eight series of which were set up side by side. Two large 

 10-liter bottles were employed, to each of w^iich four of the series were 

 connected. The purpose of the large aspirator bottle was to permit the 

 outside air to acquire the room temperature. The purpose of the cotton- 

 filled U-tubes was to prevent access of spores or bacteria to the culture 

 chamber. The entire apparatus is seen in figure 8, and an individual 

 respiration apparatus in which two Friedrich bottles were used is shown 

 in figure 7. 



