The international temperature scale between 0° and 100° C

Source abstract

Abstract The aim of the work set out in the following paper is to secure as accurate as possible a knowledge of the difference between the scales defined by the platinum resistance thermometer and the mercury in verre dur thermometer. The readings of the former are reduced by the customary quadratic equation of CALLENDAR, and the latter by using the corrections to the constant volume hydrogen scale, as determined by CHAPPUIS.* The reasons for undertaking the intercomparison may be set out briefly as follows :— In 1887 the International Committee of Weights and Measures adopted as the standard scale of temperature that of the constant volume hydrogen thermometer set up by CHAPPUIS at the Bureau International at Sevres. In order to make this scale available to investigators elsewhere, primary standard mercury in verre dur thermometers were prepared by TONNELOT of Paris to the specification of the Bureau International, and CHAPPUIS made a careful comparison between eight of these mercury <MathsOCR>thermometers</MathsOCR> and his hydrogen thermometer over the range — 24° C. to 100° C.