504 REPORT— 1888. 



as to the relation of voluine to temperature for liquids generally see foot- 

 note.' 



The more or less successful attempts of Kopp and of Schroder to find 

 relations connecting the volumes of liquid compounds at their boiling- 

 points, with volumes of their component atoms, were based on the idea 

 that liquids should be comparable among one another at their boiling- 

 points (or at points equidistant from these). 



Volume and Temioerature. Liquids — Recent Investigations. 



Ramsay ^ made a number of determinations by a new and ingenious 

 method in which the liquid was heated to the temperature of its boiling- 

 point in a small glass vessel from which, by the expansion of the liquid, 

 drops of it overflowed, as the temperature rose, into a larger vessel sur- 

 rounding it. This latter vessel had a small portion of the liquid to 

 be examined, which was kept boiling vigorously by a flame under it, so 

 that the inner vessel was kept constantly surrounded by the vapour at 

 the boiling-point of its own liquid. By this arrangement the density of 

 a volatile liquid at its boiling-point is determined. 



Thorpe ^ made a most extensive series of determinations of a large 

 number of liquids for temperatures at intervals between 0° and over 10t'° 

 (air-thermometer), every precaution being taken to secure against sources of 

 error, the results being expressed by equations of the form V=l -f-ai+ hf^ 

 -f ci^, where V is the volume at temperature t. 



To find a Simple Relation between Y and tfor Liquids. 



The question arises whether — out of all the abundant and accurate 

 material at hand as the result of experiments made on large numbers of 

 liquids at such a range of temperature for each liquid that its expansion 

 may be expressed generally with great accuracy in terms of the tempera- 

 ture by formulae like that just written — it is not possible to find some 

 simple approximate expression for the expansion which could be applied 

 to each liquid by giving to a constant in the expi-ession a number corre- 

 sponding to each. In respect of the expansion of gases such an expres- 

 sion is supplied by Gay-Lussac's law, which is an ideal law to which 

 bodies conform in the gaseous state, and is such that bodies in the ideal 

 gaseous state expand equally for equal increments of temperature. In 

 respect of liquids, as will be seen at once by inspecting tables of volumes 

 of bodies in this state, the expansion is very obviously different for differ- 

 ent liquids. Any expression, therefore, for their expansion must involve 

 some constant which is special to each. 



Bosscha '' has proposed V^ = Vq x e"' in which a is a constant charac- 

 terising each liquid. Avenarius ^ proposed another formula ; and others 

 before these dates have made attempts to find simple formulas. In 



' Despretz, Ann. Chim. (2), 73, 1840, p. 5. Pierre, Ann. Cliim. (3), 15, 1845, 

 p. 325 ; 19, p. 193 ; 20, p. 5 ; 21, 1847, p. 33G ; 31, p. 118 ; 33, 1851, p. 119. Drion, 

 Ann. Chim. (3), 56,1859, p. 5. Andreef, Ann. Chim. (3), 56, 1859, p. 317. H. 

 Kopp, Pugg. Ann. T2, pp. 1 and 223. Liebiy's Ann. 94, p. 257 ; 95, p. 307 ; 96, pp. 153 

 and 303. Elsiisser, L. Ann. 218, p. 302. 



2 a S. J. Trans. 1879, p. 463, and 1881, p. 49. 



» Ibid. 1880, pp. 141, 327. 



♦ Pogg. Erg. 5, 1871, p. 276. 



» Bull. Ah. Pctcrsb. 24. 1878, p. 525. 



