264 Oil the VolatUilxj and InJiammubUii tj 



duced from oil was lighter tlian atmospheric air. The gas which 

 could have hcen formed in that apparatus, if it had been let 

 into the fdl-house, would not have set it on fire. The gas would 

 have escaped by the steam-vent. In those parts of Mr. Wilson's 

 evidence on which he could give an opinion, he entirely con- 

 curred. From examining the model, and viewing tlie premises, 

 the impression on his u.nid was, that it was much more likely 

 that the fire hroke out in anotlier place, and was not occasioned 

 by the oil in the retort. 



Cross-examined. — Supposing the fire, when first observed, 

 seemed to have broken out in that steam -vent, which appeared 

 all ill a blaze, what would you then conceive to he tlie probable 

 cause of the fire ? 



Witness. — I do not think, if gas escaped from the retort, that 

 it could set the place on fire, unless the ^erture or pipe which 

 communicated with the steam-vent were sliut. 



Mr. F. Accum stated, that he had made experiments to ascertain 

 at Vtfhat temperature oil would emit inflammable gas. He could 

 distinguish between new and old oil, having made his experi- 

 ments with both. He found that ncv/ oil emitted permanent in- 

 flamma!)le gas at a temperature of GOO degrees. It never emitted 

 gas of that kind at a lower temperature. He had seen the mo- 

 del, and was of opinion that, with the fire which it appeared was 

 placed under the boiler, itvvould take tlie man in attemlnnce eight 

 or ton hours of constant exertion to produce so great a degree of 

 heat as would generate inflammable gas, if he were called on to 

 do so. It was impossible to produce such an effect in half an 

 hour or twenty minutes. Old oil, used again and again, would 

 give an inflammable, but not a permanent gas, at 5S0. If gas 

 had been formed in A retort, it could not have been confined 

 there, but would have escaped through the pipe. If gas were 

 formed in that court, it would immediately mount to the cupola, 

 where it would remain, unless there happened to be ani opening 

 there. In that case it would escape, and the heavier atmospheric 

 air would take its place. All inflamma!)le gases were lighter than 

 common air. There was not, he believed, any gas of an inflam- 

 mable nature that was not lighter than common air. Looking 

 at the new plan and the old, he had no doubt that the former 

 was less hazardous. He iiad placed two vessels, one containing 

 a solution of sugar, and the other of oil, in a similar degree of 

 heat ; and when the temjicrature arrived at 350, the sugar pro- 

 duced a species of inflammable gas, which ignited when a lighted 

 body approached it. This could not he done with oil. One 

 great advantage in the new plan was, that the director had a 

 complete control over the heat, which was not so in the other 

 method. The danger attending the boiling over of sugar was 



immense; 



