330 On the Chemical Evidence 



the oil before the oil attains the temperature of 500° ; but at a 

 short distance from the surface it will not continue to burn. 

 This accounts for the vapour not burning with an unintermitting 

 flame when issuing from a tube, unless the oil be heated to 

 about 600°. The cooling of the vapour is so rapid that its tem- 

 perature is diminished more than 100° in passing through a 

 pipe only a few inches in length. 



Respecting the construction of the furnace under the oil- 

 vessel at Whitechapel, I am desirous of remarking that the 

 size of a fire-place is not an accurate criterion of the quantity 

 of fuel which may be consumed in it, as that depends almost 

 entirely upon the nature of the draught. In many cases the 

 enlarging of the fire-place has a direct tendency to lessen the 

 consumption, by checking the rapidity of the current of air. 

 Thus, in the Scotch and Iiish distilleries, the quantity of fuel 

 which is burned by concentrating the draught within a mo- 

 derate-sized fire-place, is very great. Under a fifteen hundred 

 gallon still, the bottom of which is nine feet in diameter, 

 twenty-four tons of coals per day are consumed, three-fourths 

 of which, at least, are wasted, and might be saved by a more 

 judicious application of the heat. In this case, however, my 

 object was to find by the size of the fire-place, whether it would 

 hold fuel enough at once to do any harm if neglected, and al- 

 lowed to burn away under it. Any one who will take the 

 trouble of estimating the heat necessary to raise a hundred gal- 

 lons of oil from a moderate temperature to that of 600°, will, I 

 think, agree with me in my answer on this subject. 



* William Thomas Brande, Esq., Secretary of the Royal 

 Society, &c. &c., was next examined. This gentleman, who is 

 also Professor of Chemistry at the Royal Institution, stated, 

 that he " had examined the model of the new apparatus with 

 the view of giving evidence in court ; that he had made a few 

 experiments on the preceding day to prepare himself on one or 

 two points ; and that, as far as his experiments went, he could say 

 that the apparatus in question was less dangerous than the old 

 mode.'' When asked the grounds upon which he had founded 



