254 PKTTEIiSSON, OX WATEH AND ICE. 



graphy, I felt convinced beforehaiid, that no valuable observa- 

 tion of this kind could have escaped the notice of my prede- 

 cessors, and consequently was prepared to repeat their deter- 

 rainations merely in order to verif}^ the exactness of the new 

 raethods, which I wished to introduce. In many respects I 

 found this opinion confirmed — not in all. 



On the dilatation of pure liquid water there have been 

 published many treatises by prominent authors. The nnmbers 

 derived from my own researches in Table I, B. do not claim 

 any superiority to those already published by Hällström, 

 Kopp, Pierre a. O. On the contrary, I expressly wish to 

 call attention to th.e fact, that my dilatometer [see page 268], 

 if once adjusted for attaining the greatest possible accuracy 

 of determinatioii of the volumes of ice, performs its functions 

 under somewhat unfavorable circumstances, if used to measure 

 the dilatation of the melted ice, but nevertheless I think, that 

 the close coincidence of the numbers in Table I, B. with the 

 results of Pierre, Kopp, Rossetti a. O. will testify, that 

 the new instrument is not inferior to any hitherto used in 

 investigations of this kind. 



Also with regard to the change of volume of pure water, 

 when transformed into ice [at 0° C], my experiment is to be 

 considered only as a repetition of the determinations of Bun- 

 sen. ^ This might be foreseen, because in this peculiar case 

 the dilatometer performs its functions exactly in the same Avay 

 as the instrument described by Bunsen in Pogg. Ann. CXLL 



The measurements of the dilatation of pure ice hitherto 

 published cannot be compared to the determinations of Kopj) 

 a. O. on liquid water in point of exactness — naturally on 

 account of the difficulty of the problem, whatever method 

 maj^ be cliosen for the experiment. Some of these previous 

 determinations may be mentioned here. It must be observed, 

 that the result is found to be different, if the measurement is 

 made on ordinary ice, which contains air (the determinations of 

 the coefficient of linear expansion) or on ice, Avhich is entirely 

 free from air [the measurements of the cubic expansion]. 



Of the former kind there exists [besides some ancient 

 observations b v Placidus Heinrich- 'and more recent bv 



1 The previous determinations [by Er man n. Kopp, Brunner a. O.j 

 can be safely omitted here. The only result. which really can compete with 

 the determination of Bunsen, is that of Pliicker and Geissler (Pogg. 

 Ann. LXXXVI), who found the increase of vohime at 0° O = 0.09195. 



^ Bair. Acad. Phys. Abh. 1806; coefficient of exp. = O.o 00024. 



