82 operativp: technique. 



piston being then replaced b}- a column of air. Man}' methods and 

 jnaterials for rendering instruments aseptic have been recommended. 

 Immersion in carliolic or creolin solution is advised by man}' surgeons, 

 but carbolic solutiou attacks the cutting edge of bistouries, and creolin 



Fig. 6o. 



Fig. 68. 



Fig. 70. 



Fig. 72 



Figs. 68 — 73. — Scalpt-l.s. 



renders instruments slipper}', while the opacity of the emulsion prevents 

 instruments being distinguishable one from another. Immersion in 

 boiling water is a simple and practical method. The boiling-point is 



Fig. 74. — Dissecting forceps. 



raised by the addition of common salt, car'nonate of soda, carbpnate of 

 potash, or chloride of calcium, and an}' detrimental effect on metallic 

 instruments can be prevented by adding i per cent, of caustic soda. 

 Where a higher temperature of 250*^ to 260° F. is required the bath may 



