VKGA-EXrEDlTIONENS VETENSKAPLIGA ARBETEN. 255 



Ermann] a series of determinations from 1845 — 1846 by the 

 Pulkova astronomers Schumacher, Porth and Moritz. 

 They fonnd ^ 



the linear coefficient of dilatation of ice = 0.oooog424 (Schumacher) 

 » ■* > > ,> > - 0.00006387 (Porth) 



" » » » » .) j = 0.000064CO (Moritz) 



The coefficient of ciibic dilatation of the ice was determined 

 by Brun ner - 



coefficient of cubic expansion of ice — 0. 000113 



This number is decidedly too small. More exact deter- 

 minations on pure ice were made in 1852 by Pliicker and 

 Geissler. ^ The average results from 4 series of experiments 

 executed with dilatometers of diminutive size but admirable 

 workmanship Avere: 



1) coefficient of cubic expansion of ice ^ 0.000155 



2) » j » » , 5, — 0.000153 



3) > . » i , « = 0.000150 



4) '^ )> » i i :, — 0.0 0170 



Pliicker and Geissler concluded from their experiments, 

 that the coefficient of expansion by heat of pure ice is con- 

 stant and its dilatation regular at all temperatures (from O"" 

 unto —20-^ or —24° C). 



In 1879 the author, in company with H. Larson*, tried 

 to trace out the curve of volumes of the ice for every centi- 

 grade from O" to — 12°.75 C. We found it easy to verify, that 

 the average coefficient of expansion given by Pliicker and 

 Geissler was right, but we found serious reasons to doubt, 

 that the dilatation of ice was uniform. On account of the 

 imperfect construction of my dilatometer at this time and in 

 want of a balance adapted for exact weighing of great quanti- 

 ties of mercury, we were obliged to postpone the verification 

 of this observation. 



In the folloAving it will be sliown, that we were not mis- 

 taken, though we then considerably overrated the irregularity 

 of the dilatation of the ice. 



But we certainly did not then expect to find, that the 



* Kecueil des Memoires des Astronoms de Pulkowa. 18öo. 



- Ann. chim. et phys. (3) 14. (184ö). 



=' Pogg. Ann. LXXXVI. 



< Öfvers. K. V. A. Förhandl. 1870. 



