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Publish On: 2019-05-19

Steeb more

Total Post: 416

Question: Describe different observations on heat by various scientists

Reply On: 2013-12-24

lala singh

Total Post: 22

ANS: Describe different observations on heat by various scientists

Generally, when two bodies isolated from heat sources at different temperatures are placed together and allowed to remain indefinitely in contact, they attain a final temperature which is somewhere between the two original temperatures. This was explained, up to the start of the nineteenth century, by assuming the existence of a weightless, invisible fluid called caloric which was produced when a substance burned and which could be conducted from one body to another. The caloric theory served surprisingly well. But, in time, evidence that heat could not be a substance was given by Benjamin Thompson (1753-1814), an American who became Count Rumford of Bavaria. In one of his many enterprises, Rumford supervised the boring of cannon. The operation produced heat, enough to boil water placed in the bore. The apparent production of caloric was explained according to the prevailing theory by supposing that when matter was finely divided (as by the boring tool) it lost some of its ability to retain caloric. The caloric liberated from the metal shavings caused the water to boil.

Rumford surrounded a cannon by a wood box in which he placed water. The rise in temperature of this water was a measure of the heat produced during boring. Rumford showed that even a dull tool which did not cut the metal was apparently an inexhaustible source of caloric as long as mechanical work was done to rotate the tool. Writing of this experiment (1798), he ruled out this possible caloric interpretations and concluded “It appears to be extremely difficult, if not quite impossible, to form any distinct idea of anything capable of being excited and communicated in the manner the heat was excited and communicated in these experiments, except it be motion”.

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