HEAT. 



in a ftate of perfeft tranquillity, and have devoted their 

 attention to the cultivation of their refpeftive territories, and 

 to the civilization and improvement of their people. Schools 

 upon a Lancallerian plan have been cilablilhed. From the 

 zeal manifeiled by both chiefs in this noble caufe of pubhc 

 inflruftion, and the progrefs already made in carrying their 

 wife and benevolent defigns into eftett, there is p-reat reufon 

 to hope, that in a few years the illand of Hayti will exhibit 

 a population as generally educated as that of any country on 

 the lace of the globe. See Hiltory of the Illand of St. 

 Domingo, See. London, 8vo. 1818. 



HEARING, col. 2, 1. ult. infert after ear — (fee Eae.) 



HEAT, col. 2, 1. 2, infert after Calorimeter — ^in the 

 fequel of this article. 



Heat. Man)' important additions have been made to 

 our knowledge refpecTiing heat and its effedls, which our 

 limits will only permit us to inention very briefly here. In 

 doing this, we (hall follow the fame arrangement as that 

 adopted in the original article, and confine ourfelves chiefly 

 to the refults. 



Capacity for Heat, or fpecific Heat. — In the year 18 1 3, a 

 moll elaborate let of experiments was publilhed by Dela- 

 roche and Berard, on the fpecific heat of the gafeous bodies. 

 The refults of former experimeutalills reipe£ling this part 

 of the fubjett were not, as we remarked, very fatisfadtory ; 

 but from the care with which the prefent experiments were 

 made, philofophers in general appear inclined to admit their 

 accuracy. 



From the recent experiments of Dulong and Petit it ap- 

 pears, that the capacity of folid bodies follows the fame law 

 as that of liquids, that is to fay, it increafes with the 

 temperatures meaiured by an air-thermometer. They would 

 be even increafing according to thefe experimentalifts, if 

 vTe were to employ a mercurial thermometer. See the feftion 

 Espanfioit by Heat below. Thus, 



The mean capacity of iron, from 0° to 100'' = o. 1098 



o to 200 =0.1 150 

 o to 300 = O. I2l8 

 o to 350 = 0.1255. 

 In the following table, for the other metals they have 

 only given the meafures taken at 100°, and at 300°. 



Combuflton, Heat produced by — A great number of 

 laborious experiments were made by the late count Rum- 

 ford on this fubjedt, the general refults of which 

 we fliall briefly mention, as they differ in fome detrree 

 from thofe of his predeceflbrs. Thus, according to him. 

 I lb. of ^ ' 



lbs. fee. 



93-073 

 124.097 

 126.242 

 111.582 



67.470 

 107.027 



97-834 



Olive-oil when burnt melted 



Rape-oil 



Wax 



Tallow 



Alcohol 



Sulphuric ether 



Naphtha 



This philofopher likewife extended his experiments to 

 the combuition of woods, with the view of afcertainino- 

 which gave out moll heat, and under what circumftances'! 

 The general refults were, that the wood of the lime-tree 

 gives out moil heat, and that of the oak the lead, during 

 combuftion. The extreme limits of his long table, which 

 we regret we cannot give, were, tlwt 1 lb. of lime- 

 wood, highly dried over a chaffing-dilh, melted 54.210 

 lbs. of ice, while i lb. of oak, fimilarly dried, melted only 

 39.728 lbs. ■* 



Expanjwn of Bodies by Heat — The law, as recently 

 eftabhlhed by Dulong and Petit, refpefting theexpanfion of 

 the gafes has been given under Ga.s. We confine our atten- 

 tion here, therefore, to the expanfion of hquids and fohds. 

 The experiments of Dulong and Petit Ihew, that the expan- 

 fion of bodies by heat is not uniform, and that the lav.s of 

 expanfion, as laid down by Mr. Dalton, are not to be de- 

 pended upon. Thus in the following table of the abfolute 

 dilatation of mercury, it will be found that the expanfion 

 above the boiling point of water increafes as the temperature 

 increafes according to the air-thermometer, which from the 

 uniform expanfibility of the gafes is the only one that iiidi- 

 cates equal meafures of temperature. 



Table I. — Expanfion of Mercury, 



Table II Expanfion of Glafs. 



In the above table, on the dilatation of glafs, the third 

 column fliews that its expanfion is not uniform, but increafes, 

 except between 0° and 100°, where it is the fame as itated 

 by Lavoifier and Laplace. The laft column contains the 

 degrees which would be indicated by a thermometer formed 



of 



