

Boiling-point. 



Chloroform 





60-6° 



Methylic alcohol . 





64-5 



Methylic ethylic 



alcohol 





1:1 





69-8 



Methylic ethylic 



alcohol 





3:7 





72-4 



Ethylic alcohol .. 





78-1 



Ethylic propylic 

 16:3 



alcohol 



79-8 



Benzole 





79-9 



Ethylic propylic 



alcohol 





7 :4 





82-2 



Isobutylic bromide 

 Ethylic propylic 





87-4 



alcohol 





1:8 





91-5 

 96-0 



Propylic alcohol . 





Isobutylic alcohol 





105-7 



396 Intelligence and Miscellaneous Articles. 



place in two ways — either by comparison with a standard thermo- 

 meter at different temperatures, or by calibration and determina- 

 tion of the thermometric constants. The comparison of the thermo- 

 meters is made between 0° and 50° in water-baths ; above 50° 

 in boiling-point apparatus with reversing condensers, in which 

 liquids of various boiling-points are used for the determinations. 

 The following liquids were found to be especially suitable : — 



Boiling-point. 



Toluole 1094° 



Isobutylic acetate 114'1 



Paraldehyde 124'6 



Amylic alcohol 129-8 



Xylole 139-4 



Amylic acetate 14O0 



Bromoform 148"9 



Turpentine about 1600 



Aniline 184-3 



Dimethylamine 194-0 



Methylic benzoate 199-3 



Toluidine 199-5 



Ethylic benzoate 212-3 



Chinoline 235-9 



Amylic benzoate 259*5 



Glycerine 2901 



Diphenylamine 301*9 



By boiling various liquids under diminished pressure constant 

 temperatures may be obtained, and this method is also used in the 

 Imperial Institute between temperatures of 50° and 140° (compare 

 Beibldtter, vol. xvi. p. 507). The statement as to the correction 

 refers to thermometers completely immersed, and corrections must 

 be introduced afterwards for the projecting thread (compare also 

 Eimbach, Beibldtter, vol. xvi. p. 417). 



The second kind of investigation which is indispensable for 

 accurate instruments consists in calibrating them, determining the 

 distance of the fixed points, &c. The methods for this are described 

 in the Trav. et Mem. du Bureau inter national, &c. The position of 

 the freezing-point at f is, according to Bottcher, 



E* = E 100 + 0-0055 (100-0 +0'0 6 3 (100-* 2 ). 

 The reduction of the data of the mercurial thermometer of Jena 

 glass 16'" to those of the air-thermometer, according to Wiebe and 

 Bottcher, are calculated from the formula 



S= -0-0,280 (100-0-0-0 6 299 (100-* 2 ), 

 in which t stands for degrees of the mercury- thermometer, 8 the 

 reduction to the air-thermometer (see Beibldtter, vol. xvi. p. 352). 



For testing the thermometers at low temperatures mixtures of 

 salts are used to— 33° ; for still lower temperatures mixtures of solid 

 carbonic acid with mixtures of alcohol and water in various pro- 

 portions (to — 78 0, 8). Above 300° baths of fused nitre are used ; 

 the best is a mixture of potassium and sodium nitrates in equal parts 

 melting at 230°. Thermometers of Jena glass filled with nitrogen 

 may be used after a previous continuous heating to about 480° 

 to 450°. — ZeitscJvrift fur analyt. Chemie, vol. xxx. p. 1 (1891) ; 

 Beibldtter cler Pliysxk, vol. xvii. p. 100. 



