LIQUID MEDIA. IO3 



right angle to the side (Fig. 37). The former, 2, 

 is of metal, and the latter, a, of glass fitted with 

 a thermometer, the bulb of which, k, is contained 

 within the box. A partition, s, keeps up a current 

 between the openings of the pipes, which are 

 supported on a stand and connected by tubing 

 with the hot water supply (Fig. 38). 



A mixture of paraffine and vaseline is recom- 

 mended for indicating the temperature of the 

 chamber, and experience has shown that if a tem- 



FIG. 39. SIMPLE GAS CHAMBER. 



perature of 37 C. be required the temperature of the 

 water in the box must range between 42 and 47 C. 



Gas Chambers. To investigate the action of 

 gases or vapours upon micro-organisms, a modi- 

 fication of the simple moist chamber (Fig. 31), 

 may be employed (Fig. 39). 



A piece of glass tubing is first fixed to the slide 

 by means of sealing wax, and the ring of putty is 

 so placed as to include the end of this, leaving 

 a small interval at the side, or a little notch is 

 made in the putty opposite, so as to afford an exit 

 for the gas or vapour (Fig. 40). 



