LIQUID MEDIA. 



99 



temperature of the copper plate may be approxi- 

 mately that of the body, the lamp is so adjusted 

 that a fragment of cacao butter and wax placed 

 close to the preparation is melted. 



For more accurate observations, the apparatus 

 shown in Fig. 34 may be employed. The vessel/", 





FIG. 33. SIMPLE WARM STAGE SHOWN IN OPERATION. 



filled with water which has been boiled to expel the 

 air, is heated by means of a gas-flame at g. The 

 warmed water ascends the indiarubber tube c to the 

 brass box a. The box is pierced by a tubular 

 aperture to admit light to the object, and has an 

 exit tube c', by which the cooled water from the 





