324 On the Chemical Evidence 



for if that is wide the gravity of the mercury will overcome the 

 capillary attraction of the tube, and the fluid metal will oscillate 

 freely, as it does in a barometer. 



Mr. James Harris, a sugar-refiner of Liverpool, was the next 

 evidence of any consequence that was called. This gentleman 

 deposed that he had been a sugar-refiner fourteen years ; that he 

 had employed two processes ; — the common process of boiling 

 with a fire under the sugar-pan, and that of boiling by means of 

 oil heated in an open vessel ; that the danger of fire was lessened 

 by the adoption of the oil process, because the sugar might at 

 any time have been raised out of the heated oil in an instant ; 

 that there is great danger in boiling sugar by the common 

 process, as it is apt to boil to excess, until the sugar becomes 

 ignited by the heat below; that, in consequence of this danger 

 he erected three sugar-pans, which he boiled by means of 

 melted tallow, and afterwards by heated oil ; that in six months 

 he abandoned both these processes in consequence of the dis- 

 agreeable smell which they occasioned, and reverted to the 

 ancient method of boiling over a naked fire ; but that he 

 thought he should not continue that process much longer, but 

 adopt the new one invented by Mr. Wilson. 



Observations. — This gentleman, in describing the process 

 which he employed, stated it to be conducted in an open pan, 

 like the one in common use, but immersed in another pan con- 

 taining melted tallow, or heated oil. Having seen a model of 

 this apparatus, the nature of it will, perhaps, be more generally 

 understood, if I add, that the vessel containing the oil or tallow, 

 was fixed in brick- work, over a common close fire-place, well 

 contrived for heating the said vessel ; that the sugar to be re- 

 fined was put into a copper pan, suspended by three strong 

 chains, so as to allow it to sink sufficiently within the heated 

 oil ; that the upper rings of these chains were hung upon the 

 short arm of a powerful lever, which was permanently fixed 

 over the pans above-mentioned ; and that, by this arrangement, 



