VEGA-EXPEDITIONENS VETENSKAPLIGA ARBETEN. 



277 



Every substance, as a rule, ought to expand its volume 

 when heated and contract it on cooling. Every exception to 

 this rule either in the apparent or in the real change of vo- 

 lume is in this and subsequent tables denoted by the sign — . 



As starting-point for my dilatometric experiments ^ I have 

 always chosen 0° C. The reason is obvious. This temperature 

 can be maintained steady as long as you please, if the appa- 

 ratus are surrounded with pure snow moistened with distilled 

 water. I consider it to be the natural starting-point of all 

 practical volumetrie investigations, determinations of spec. 

 gravity, calibrations etc. Therefore the unit of all volumes 

 enumerated in this paper is 1 cc. of the liquid or solid sub- 

 stance at 0° C. The specific gravity was always determinecl 

 by the Sprengel pycnometer at O" C hut afterwards referred 

 to that of pure water at + 4° by calculation. I denote this 

 by the sign 



I take a special pleasure in mentioning, that I bad the 

 advantage of securing the assistance of my former companion 

 Mr. Larson in a part of the foregoing and also of the sub- 

 sequent series of determinations. At my wish Mr. Larson 

 undertook the leading of experiment I and likewise of V in 

 the next chapter. With the assistance of Mr. Larson I found 

 it possible to take the observations at regular thermometric 

 intervals of temperature. 



* In order to give a clear view of the experimental proceeding, I will 



here enumerate the weighing results belonging to I. 



Weight of the mercury, which fills the dihitometer entirely 



at 0° C 676.1150 grm. 



Weight of mercury in the capillary tiibes, the stern, stop- 

 eocks etc. which are not exposed to changes of tempera- 

 ture 7.4136 s 



L 668.7014 grm . 



After the chjse of the exi)eriments the weight of that mer- 

 cury, which together with the water filled the instrument 



entirely at 0°, was found = 189.63 90 grm. 



therefrom to deduct 7.4136 » 



Qt 182.2254 grm. 182.2254 grm. 



"Wi 486.4 700 grm. 



Weight of mercury imbibed through sb» at melting 44.1144 grm. 



