322 On (he Chemual Evidence 



alteration except becoming darker coloured, and in a trifling 

 degree thickened ; that when the rubbish was cleared away after 

 the fire, the oil vessel was found standing in its original position, 

 the four-inch wall which was on one side of it was as perpendi- 

 cular as at first, and there was no fissure or rent in the oil- 

 vessel ; that the copper pipes could not possibly have burst from 

 the action of the pump, as they were larger in diameter than the 

 valves, and therefore there could be no pressure in them." On 

 being cross-examined by Mr. Scarlett, he stated, that ** he had 

 taken out three patents for boiling sugar, and had formerly been 

 engaged in chemical manufactures; that whale-oil does not boil 

 under 640°, or thereabouts ; that the thermometer was fixed in 

 the oil vessel, with its bulb about three inches beneath the sur- 

 face of the oil; that when the bulb of a thermometer is broken, 

 a portion of the mercury usually rises to the top of the tube ; 

 and although the fire was burning for a week in the ruins, the 

 oil-vessel was dug out in a perfect state, so much so that water 

 was afterwards boiled in it without its undergoing any repair." 



On the foregoing evidence, I am desirous of making a few 

 observations. Mr. Wilson stated " that sugar becomes de- 

 composed when heated to a temperature of 344°, and then 

 gives out inflammable gas." In the first experiment which I 

 made upon sugar, heated in a copper pan, the gas arising from 

 it would not ignite by a lighted match when the sugar had ac- 

 quired the heat of 370°, but at that temperature the sugar itself 

 burnt with a very strong and permanent flame. In a subse- 

 quent experiment, made also in a copper pan, I did not find the 

 gas inflammable until the sugar was heated to 386°, and the 

 sugar did not take fire of itself until the thermometer stood at 

 398° ; and in an experiment made in a small glass retort, the 

 gas did not ignite until the sugar was heated to 470°. This is 

 a remarkable fact, but I have found in other cases, that sugar 

 may be decomposed at a lower temperature in copper than in 

 glass. 



Mr. Wilson also stated that " when whale oil is heated to 

 600°, it gives out inflammable gas, but not under that tempera- 

 ture." When Messrs. Severn's first action was tried, my opinion 



