CONTRIBUTIONS FROM THE ZOOLOGICAL LAB- 

 ORATORY OF THE MUSEUM OF COMPARA- 

 TIVE ZOOLOGY AT HARVARD COLLEGE. 

 E. L. MARK, DIRECTOR.— No. 139. 



A PARAFFIN E BATH HEATED BY ELECTRICITY. 



Under the stimulus of disastrous explosions of gas in other 

 museums and some unpleasant experiences in our own, it was 

 decided somewhat over a year ago to replace, as far as practica- 

 ble, heating by gas in the Museum laboratories with heating by 

 electricity. The greatest danger from the use of gas is incurred 

 where two or more lights are kept constantly burning in the 

 same room. All of our constant burners for heating water- 

 baths, warm ovens, etc., have been for many years supplied with 

 the Koch automatic cut off, so that in case of accidental extin- 

 guishing of the flame, the cooling down of the burner would 

 automatically shut off the gas supply. But the lever of the 

 Koch burner will not always work, even though loaded with a 

 weight greater than that which it carries when it comes from 

 the maker ; moreover, the metal, on the expansion and contrac- 

 tion of which the tripping apparatus depends, after a time loses 



release the lever and cut off the gas. 



The Departments of Botany and of Zoology were already in 



desirable to retain if they could be provided with a suitable 

 electric heating apparatus. With the aid of suggestions from 



tion of constructors of electrical apparatus, a plan was finally 



ordinary paraffine water-baths 



