The Catalytic Action of Platinized Asbestos 223 



In all cases where the presence of suspected micro-organisms is to 

 be demonstrated, it is necessary to make both aerobic and anaerobic 

 cultures. For routine work of this kind, this method of Wright is 

 probably the most convenient yet suggested. 



6. The Catalytic Action of Platinized Asbestos upon Hydrogen 

 and Ojcygen. — This method seems to have originated with Laidlaw 

 (British Medical Journal, March 20, 1915) who tried porous platinum, 

 colloidal platinum, and colloidal platinum and sodium formate in 

 vaxious ways for the absorption and combination of the oxygen. 

 His preference was for the method in which porous platinum was 

 used as a catalysant, which is, briefly, as follows: 



■ "Short pieces of platinum wire are fixed into glass holders at the blow-pipe 

 and the free ends are wrapped tightly round small pieces of gas carbon or other 

 porous material which will char readily and secured by twisting round the main 

 piece of wire. These pieces of carbon are then heated 

 in the flame from a Bunsen burner to expel the air, and 

 dipped while still hot into a strong solution of platinic 

 chloride. After soaking for some time, they are removed 

 and dried over the flame. They are then heated red 

 hot and redipped and the process repeated two or three 



times. It will be found theii that, on removal from the / ;:.i j o 



flame, the reduced platinum on the surface of the carbon < '' " ^ — i 

 will absorb sufiScient oxygen from the air to keep the \ / 



mass a dull red until all the carbon is burned away. . . \ I — c 



The glass is cut short and pushed into the center of a 

 cork. . . . Suppose that an anaerobic culture is desired 

 on a blood agar slope in a test-tube. The tube is infected 

 in the usual way. It is turned upside down and the 

 cotton-wool plug removed. A sterile glass capillary tube 

 connected with a hydrogen apparatus (Kipp's apparatus) 

 and with a cotton-wool plug in it is introduced from 

 below, and a brisk stream of hydrogen run into the 

 test-tube. No precautions are necessary to keep the 

 hydrogen from (Uffusing out of the test-tube except that 

 the remaining operations are carried through rather 

 quickly. The capillary is removed and the platinum 

 armed cork, which has been sterilized by passing through 

 a flame is pushed home. If an ordinary cork is used it is 

 advisable to paint the joint with melted paraffine wax. 

 If the right amount of hydrogen has been introduced Fig. 64. — Sketch 

 the platinum will glow dull red as soon as it is intro- of anaerobic appara- 

 duced and continue to do so until all the residual oxygen tus for the cultivation 

 is used up in forming water. If two little hydrogen has of absolute anaerobes 

 been led into the tube, the platinum will burn white hot in test-tubes (Smillie). 

 and an explosion will result. Using this method the 



organisms of tetanus, botulismus and malignant edema grow with great freedom 

 and nearly the whole surface of the agar was covered with growth in forty- 

 eight hours. Transplants from these gave visible growths in fourteen hours." 



The method was somewhat modified and amplified by Mcintosh 

 and Fildes (Lancet, Lond., April 8, 1916) who used asbestos wool 

 impregnated with palladium black, in the place of the platinized 

 carbon. It has also been amphfied and considerably improved by 

 Smillie (Jour. Exp. Med., 191 7, xxvi. No. i, p. 59), who found that 

 Laidlaw's tubes did not always prove to have had the oxygen com- 

 pletely removed. SmiUie's improvement is described as follows: 



