1914] Woodivorth: A New Self -Regulating Paraffin Bath 41 



A piece of cardboard may be placed over the flask to keep the dust 

 out of the paraffin and a towel is usually thrown over it to conserve 

 the heat when warming up the bath. It takes about half an hour in 

 a room with a temperature of about 16° C to melt the paraflSn. If a 

 thicker covering were used the bath would heat up more quickly and 

 if less chloroform were used or the flask were made smaller, it would 

 also get hot sooner. The same would be true if a lamp of more than 

 sixteen candle power were used. After it is once warmed up it main- 

 tains an invariable temperature, whether covered or not, except on our 

 cold days (5° C), when the cover may be necessary to prevent a ring 

 of paraffin graduallj^ crystallizing around the edge or even a complete 

 fllm forming over the surface after a time. 



Fig. 2. Cross-section of the paraffin bath shown in figure 1. The shaded 

 portion below near the electric lamp shows the chloroform; that in the cup 

 above indicates the paraffin. 



The heat of the sixteen candle power lamp (110 volts) is not suf- 

 ficient to cause the chloroform to boil vigorously when the flask is of 

 the size shown in the illustration, indeed the liquid scarcely seems to 

 boil at all. The sixteen candle power lamp has proven ample to main- 

 tain the proper temperature and to cause on the average about eight 

 centimeters of the vertical tube to warm up. 



An important feature of this form of bath is the illumination of 

 the cup which insures the keeping of the paraffin clean because the 

 presence of dirt will be noticed at once. 



