CULTIVATION IN HYDROGEN 



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^K Such an apparatus — a modification of that originally devised 

 ^»r Dr Roux for use at the Pasteur Institute — is shown in Fig. 17, 

 ^and can be set up without difficulty by any furnisher of bacterio- 

 logical or chemical apparatus. It consists of three two-necked 

 Wolff flasks — two, " a " and " d " as figured, of 4 to 5 litres capa- 

 city, with intercommunication by means of two glass syphon tubes 

 extending almost to the bottom of each and joined together at the 

 top by a short length of india-rubber tubing "/"" furnished with a 

 screw pinchcock, and the third " c " of smaller size (500 cc.) connected 



Fig. 17. 



up with the flask " d " by means of a length of S-shaped glass tub- 

 ing ^ returned on itself, and fitted with an india-rubber connection. 



Of the two larger flasks the one " a " serves as the reservoir of 

 dilute acid, and is furnished with a stoppered inlet tube "d" to 

 which is connected a short length of india-rubber tubing, whilst in 

 the other " d" a layer of sheet zinc clippings reposes on a bed of 

 broken glass tubing extending to about one-half the height of the 

 flask. The smaller flask is filled to about one-third its capacity 



* As there is a tendency to regurgitation from the flask "r" to the flask 

 " 5," when working with the vacuum pump, this tube should be as long as pos- 

 sible, and have at least a double return. 



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