Frontispiece. 



FIG. 1. Compound microscope with thermo-stage. The heating plate is clamped 

 on the stage of the microscope and is warmed by means of an alcohol lamp 

 or small gas burner. The temperature is indicated on the thermometer. 

 The thermo-stage is almost indispensable in the examination of proximate 

 principles, especially organic substances where differences in melting-points 

 may be used in their identification. 



Thermo-stages are also constructed which are electrically heated. These 

 are provided with an adjustable electro-thermostat that automatically main- 

 tain a constant temperature. These are usually made for the study of 

 living organisms, but can be obtained to register as high as 100 C. 



