( 370 ) 



its position of equilibrium. So far as it proved necessary, a correc- 

 tion curve was plotted of these oscillations (see Plate III Conini. N". 83, 

 December 1902). As a rule, however, these deviations were so slight, 

 that they could be neglected. 



Part of the capillary glass stem of the thermometer has the 

 same temperature as the liquid bath. The length of this part is 

 derived from the indications of a float ^) in the cryostat, which is 

 omitted in the drawings, not to render them indistinct. In order 

 to find the distribution of temperature in the other parts of the 

 capillary within the cryostat, special determinations are made, 

 viz. a. by means of a resistance thermometer placed by the side of 

 the capillary, (see Comm. N°. 83 Plate II ')), b. with the aid of a 

 thermoelement, whose place of contact was put at different heights 

 in the cryostat, the distribution of temperature in the cryostat was 

 examined for the case that liquid air, liquid ethylene or liquid 

 hydrogen was used as bath, and finally c. the distribution at other 

 temperatures of the bath was derived from this distribution. This 

 may be deemed sufllicient, as the volume, the temperature of which 



is determined, amounts only to of the reservoir, and as an error 



^ 3000 



of 50° in the mean temperature of the capillary corresponds to 

 only 0°.01 in the temperature of the bath, while the agreement of 

 the observations sub a and b show that an error of more than 20° 

 is excluded. 



§ 5. Calculation of the temperatures. 



The calculation of the zero point is made by reducing the observed 

 pressure of the gas to that under fixed circumstances, the same as 

 taken in Comm. N". 60. Put: 



Vq the volume of the reservoir at 0°. 



M, the volume of that part of the glass capillar}^ that has the same 

 temperature t as the reservoir. As such is considered the part 

 immerged in the liquid bath, to which is added 2 cm. of the 

 part immediately above it. 



M,' and ?/," the volumes of the parts of the glass capillary in the 

 cryostat outside the bath at temperatures t^ and t^'. 



w, the volume of the part of the glass capillary outside the cryostat 

 (Wj'") and of the steel capillary at the temperature t^. 



^) For determinalious on liquid hydrogen no float was used. The level of the 

 liquid in the bath was derived from the volume of the evaporated gas. 



-) The lowest part from f^ to ^12 with close windings is 9 cm., the part where 

 the windings are farther apart (about 20 cm.) reaches up to in the top of the 

 cryostat. 



