1821.] Dr. Bostvck on Whale Oil. 4T 



of the boiler. The oil occupied about two-thirds of the vessel - 

 it had a concave bottom, and was closed air-tight, except that a 

 tube of half an inch diameter was inserted into its uppeppart. 

 The temperature employed was 360°, and the oil was carefully 

 kept at that degree of heat during 12 hours each day. In the 

 different trials the process was continued for 22, 23, 26, 38, and 

 66 days respectively, until, in one instance, it was extended to 

 68 days. The substance employed was the whale oil of conw 

 merce^ in the state of purity in which the article is usually exhi- 

 bited for sale. 



When the oil was examined, after having been kept at the above 

 temperature for the periods above stated, its physical properties^ 

 , were considerably altered, its colour was nearly black, its con- 

 sistence thick and tenacious, and its odour empyreumatic. 

 When heat was applied to it in this state, after it had beeii 

 cooled down to the temperature of the atmosphere, the firsfc 

 effect was to render it more fluid ; and at higher degrees of heat 

 its consistence seemed to be considerably less than that of recent 

 oil. While the oil was in the boiler, and at the temperature of 

 360°, an internal motion took place among its parts, that seemed 

 to arise from some portion of it being converted to the aeriform 

 state, and suddenly condensed : this was indicated by a peculiar 

 sound emitted from the vessel analogous to the simmering of 

 water before it is raised to the proper boiling point. It was 

 observed that the simmering, if we may so term it, diminished 

 as the oil exceeded the temperature of 400°; and after it had 

 acquired the heat of abcut 450° was no longer heard. 



But the most material alteration in the oil was the property* 

 which it had acquired of emitting vapour when it was subjected 

 to temperatures which would have had no effect of this kind 

 upon recent oil. Both the quantity of the vapour, its chemical 

 composition, the mode of its generation, and the degree of the 

 thermometer at which it first appeared, were very different in./ 

 the different experiments ; and there does not appear to be suffi- 

 cient data for forming a correct opinion upon any one of these 

 points. One of the circumstances which seemed the most 

 favourable for its production was the rapidity with which the 

 fluid passed through a certain range of temperature. Oil, for 

 example, which was steadily kept at 360°, although it had 

 acquired the dark colour, seemed to produce little aeriform fluid 

 of any kind, with perhaps the exception of a portion of carbonic 

 acid ; and there is some reason to suppose that it might bear 

 even a higher temperature, provided the heat be cautiously 

 applied. But if, on the contrary, the heat be more rapidly raised, 

 a copious discharge of an aeriform fluid takes place, which 

 essentially consists of inflammable and aqueous vapour mixed in 

 , variable proportions. The total amount of vapour emitted, the 

 proportion of the a^jueous to the inflammable part, and the che- 



