\\'\\\\ tliose ol' l;il»lo I ol' this ( 'oiniiiiiiiicUioii, the (lirrercuccs fV)r 

 ~U):r\ J.S3 and 217^') respect ivolv are: 



+ O.iVI'A 4- 0.021 i\\u\ - 0.012 

 coiTespuiidiiijj, lo 



0\040, O .086 aiul 0^022. 



From lliis wc derive that down to — 217'^ the variations in the 

 temperature coelillcients owing to the new winding of the wire, thongh 

 not imperceptible are extremely small. 



2. A compai'ison between two resistance calibrations, for which 

 the same hydrogen and resistance thermometers were nsed, in the 

 neighbonrhood of the boiling point of hydrogen by means of the 

 determinations of March 19 and Jnly 1. The difference is 



0.0049 ii = 0^.046 and exceeds — deg. which has been derived as 



the limit of accnracy for measurements to — 217'. This must pro- 

 bably be ascribed to the fact that the measurements of the resistance 

 are less accurate l)ecause they are made with the Wheatstone 

 bridge and not with the dilferential galvanometer ^). 



3. A comparison between the indications of the thermometer 

 tilled with distilled hydrogen and the one used before and tilled 

 with electroiytical hydrogen, by means of the determination of 

 July 1, abstracting from the errors of obser\ation of the hydrogen 



1) For — 517° tills diffei-ence just reaches the limit of accuracy derived in Com m 

 N'. 95e and for the two other temperatures the ditïerence only little exceeds this limit. 



For — 183° another reason may be given for this difference. To a certain extent 

 it must probably be ascribed to the circumstance that the earlier determinations 

 (of June 30 and July 6 '06) like those at — 217° of June 30 '06 must be consi- 

 dered as less reliable. It appeared namely during an investigation started in Dec. 

 1906 that the steel capillary was no longer absolutely tight and this may also 

 have been the case when the measurements under discussion were made. The 

 latter becomes probal)ie when we direct our attention to the great variations of the 

 zero during these determinations, viz 0.33 mm., to which we alluded in § 11 

 of Comm. N '. 95c without being able to explain it then. 



The fault may have arisen because at the end of May '06 the thermometer has 

 partly been taken to pieces and the capillary was bent too much. The observations 

 made before June "06 were not intkienced by this fault. 



2) The accuracy of the WnEAXSTONE bridge is perfectly sufficient for higher 

 temperatures below O"" G. (comp. Comm. N'\ 99b % 2 for temperatures till — 217°), 

 but owing to the disadvantageous influence of the connecting resistances, it falls 

 short for measurements in hydrogen where the variation of the resistance becomes 

 so small. Therefore, simultaneously with the measurements of table I in hydrogen 

 made with the Wheatstone bridge, we have calibrated another thermometer 

 Ptu' with the differential galvanometer in order to fix the temperatures below 

 — 217° 



