TABLE 237. 



CHANCE OF THERMOMETER ZERO DUE TO HEATING.* 



When a thermometer is used for measurements extending over a range of more than a few degrees, its indications are 

 generally in error due to the change of volume of the glass lagging behind the change of temperature. Some data 

 are here given to illustrate the magnitude of the change of zero after heating. This change is not permanent, but 

 the thermometer may take several days or even weeks to return to its i.ormal reading. 



TABLE 238. 



CHANCE OF THERMOMETER ZERO DUE TO HEATING. 



* Allihn, " Zeits. fiir Anal. Chem." vol. 29, p. 385. 



t W. Fresenius, "Zeits. fiir Anal. Chem." vol. 27, p. 189. See also, for this and following table, Wiebe in the 

 " Zeitschrift fiir Instrumentenkunde," vol. 6, p. 167, from which Fresenius quotes. The thermometer referred to i 

 this table belonged to the Kaiserlichen Normal-Aichungs Commission. 



SMITHSONIAN TABLES. 



230 



