154 PURE CULTURES FROM PATHOLOGIC MATERIAL 



the purification of the hydrogen is much simpler. The first wash 

 bottle may then contain a solution of iodine and iodide of potash and 

 the second one concentrated H 2 SO 4 . These bottles will wash and 

 then dry the gas. 



In order to replace the atmospheric air in the tubes, flasks, or Petri 

 dishes containing the anaerobic cultures by hydrogen, special arrange- 

 ments are always necessary to lead the gas in and then to close the 

 culture medium container in an air-tight manner. The Novy jar is 

 the apparatus easiest to handle. It comes in a high pattern adapted 

 for tubes and flasks and in a low pattern adapted for Petri dishes. 

 This jar has an inlet and an outlet tube which can be closed by air- 

 tight glass stopcocks. After a Novy jar, containing culture tubes or 

 plates, has been filled with hydrogen, it is well to seal the lid and the 

 stopcocks with melted paraffin as an additional precaution. In 

 order to see whether all atmospheric air has been displaced from the 

 Novy jar or other apparatus used the following test should be made 

 from time to time. The outlet tube of the jar is connected with a 

 small rubber tube which carries at its outer end a small glass tube 

 bent at right angles. The free limb of this rectangular glass tube 

 is lead into a test-tube held with its closed end upward. After a short 

 time the glass tube is withdrawn; the mouth of the test-tube rapidly 

 closed with the thumb and the tube now inverted so that its mouth 

 points upward. A match is lit and held at the mouth of the test-tube, 

 and if the gas is pure it burns with a blue, non-luminous flame; if 

 still mixed with atmospheric air there will be a slight explosion. 

 This test, which should be repeated until the result indicates pure 

 oxygen, must be made at some distance from the Kipp apparatus. 

 The latter is best rigged up under a hood. Where none is present the 

 escaping hydrogen can be let out of the room by the following simple 

 arrangement: A small hole is made with an auger in a window frame 

 and a glass tube passed through the hole. This glass tube is con- 

 nected with the outlet tube of the Novy jar by a piece of small caliber 

 rubber tubing and the hydrogen gas flowing through the apparatus 

 is carried out of doors. 



Removing the Oxygen from the Air by Chemical Means. This 

 method, first used by Buchner for the cultivation of anaerobic bacteria, 

 is based upon the principle of absorbing the oxygen of the air in a 

 closed vessel by an alkaline solution of pyrogallic acid. Applied to 

 single-culture tubes the method is practised as follows : A large test- 

 tube, into which the much smaller culture tube fits easily, is provided 

 with a tightly fitting rubber stopper. One gram of pyrogallic acid 

 and 10 c.c. of a 10 per cent, solution of potassium hydrate are placed 

 in the large tube. The inoculated culture tube, with a piece of thin 

 string fastened around the mouth, is suspended in the large tube and 

 the string is held in place by the rubber stopper of the large tube. 

 The latter is then sealed by pouring paraffin on top of the rubber 

 stopper and around it. After this the tube can be incubated. If a 



