388 On the Heat developed in Combustion 



occurred to me, even after I had my new apparatus, and 

 of the means I employed to surmount them. I even 

 found myself exposed to dangers, which it is necessary 

 for me to mention as a caution to those who may under- 

 take the same inquiry. 



When I made the experiments with highly rectified 

 alcohol, and more particularly with ether, I found it very 

 difficult to prevent a portion of these volatile liquids 

 from escaping in the state of vapour from the bulk of 

 them remaining in the lamp. I procured a small lamp, 

 resembling in shape a small round snuff-box, with a noz- 

 zle rising from the centre of the circular plate, which 

 closed it atop ; and on this plate was fixed a small pan, 

 to hold cold water, for keeping the nozzle cool and pre- 

 venting the heat from being communicated to the body 

 of the lamp. But this precaution was not sufficient, 

 when I burned ether, as I found to my cost; for, though 

 the pan was twice the diameter of the lamp, and filled 

 with very cold water, the water was so heated in a few 

 minutes that an explosion took place from vapour of 

 ether kindling in the air with a flame that rose to the 

 ceiling. Indeed it was near setting the house on fire. 



Warned by this accident, I procured a new lamp, much 

 smaller than the former, being only an inch in diameter 

 and three quarters of an inch deep ; and its nozzle, which 

 was only two lines in diameter, was three quarters of an 

 inch high. To keep this small lamp cool while burning, 

 it was placed in a small pan, and kept constantly im- 

 mersed in a mixture of water and pounded ice to within 

 a quarter of an inch of the extremity of the nozzle. 

 These precautions were sufficient to prevent any explo- 

 sion, though not the evaporation either of the ether or of 

 the alcohol. This fact I learned from observing that, as 



