on the Oil Questmi. 113 



immersed in the oil, while the other was made to rest directly 

 upon the bottom of the oil vessel, and both dipped into that 

 part of the vessel which was immediately over the fire. 



When every thing was thus arranged, Mr. Cooper undertook 

 the management of the fire; and, by close attention thereto, 

 the heat was brought up as rapidly as possible ; while another 

 of our party attended to note down the increasing temperature 

 of each thermometer every five minutes. At similar intervals 

 one or two of us attended to the leaden tube, which issued per- 

 pendicularly from the top of the oil vessel to the height of twelve 

 feet, in order to examine the nature of the vapour which issued 

 from it. It is necessary to observe, that this tube was originally 

 sixteen feet long, but the end of it having been accidentally 

 injured by the workmen, we cut off four feet before we com- 

 menced our operations. 



In consequence of the great fire which was kept up, the oil 

 very soon began to give out a large quantity of vapour, the 

 nature of which was examined every five minutes, by the appli- 

 cation of lighted candles and pieces of ignited deal ; but in no 

 instance did we find any thing that was inflammable issuing 

 from the tube ; but, on the contrary, every ignited substance 

 was immediately extinguished. 



When the oil attained the temperature of between 400° and 

 500°, the smell became very offensive, and the vapour which 

 issued from the leaden pipe was very abundant, but it was still 

 uninflammable. 



All this time the fire was urged as much as possible, and was 

 so intense, that the door of the furnace was continually red- 

 hot. Every five minutes the temperature of the oil, as indi- 

 cated by the two thermometers, was noted down, and two of 

 us went up stairs to examine the safety-tube connected with the 

 oil vessel, and though vapour was constantly passing ^hrough 

 it, in no instance did we find it inflammable, but the reverse. 



When the temperature of the oil was raised to something 

 under 550°, I was obliged to desist from trying the inflamma- 

 bility of that which issued from the tube, as the large room, 

 which is fifty-four feet by sixty feet, and nearly twelve feet 



Vol. XI. I 



