40 MEASUREMENT OF HIGH TEMPERATURES. 
made the basis of measurement. Both methods give the same result. 
The thermal comparisons are based on the porcelain air-thermometer 
of Deville and Troost. Furthermore, Erhard and Schertel 1 at about 
this time made elaborate re-determinations of the melting points of very 
pure Prinsep's and other precious alloys, by simultaneously exposing 
these alloys and a porcelain air-thermometer in a large muffle. Having 
obtained a series of silver- gold and gold-platinum alloys, melting be- 
tween 984° and 1,408°, they apply these data practically, determining 
by means of them a table of meltiug points of known silicates (1,208° 
to 1 ,444°). Coneehy, 2 at the suggestion of Carnelley, used fusing points 
to find the temperature at which arsenic volatilizes. Silicious mixtures 
of gradually increasing fusing points have been investigated by Seger, 
in Germany, and his tables are printed in full by Lauth, 3 who also gives 
some attention to alloy fusions. Seger's mixtures are made of feldspar, 
chalk, and kaolin, substances easily obtained, and they fuse between 
1,100° and 1,700°. Finally, the data of LeOhatelier 4 must be mentioned, 
by whom fusing points, as well as temperatures of chemical decompo- 
sition, have been measured. Tables of melting points are published 
in great fullness by Carnelley. 5 Excellent and serviceable tables of this 
kind are also to be found m Landolt and Boernstein's 6 Physikalisch- 
chemische Tabellen. 
Specific heat.—T\iQ measurements of temperature calorimetrically 
dates as for back as Guyton-Morveau, 7 in whose pyrometric researches 
it is definitely proposed. Schwarz 8 used both iron and water as well 
as platinum and mercury. Coulomb, 9 in studying the relation between 
hardness aud permanent magnetization, determined the temperatures 
before quenching or annealing, by submerging the rods in water under 
known conditions. Clement and Desormes 10 use iron and water for tech- 
nological temperature measurement, as was proposed also by others. 11 
In general, however, neither is any attention given to the variation 
of specific heat and temperature, nor is allowance made for errors 
by radiation. 
1 Erhard u. Schertel : Jahrbuch fur das Berg u. Hiitten-wesen im Konigr. Sachsen, 
1879, p. 154. 
2 Conechy: Chem. News, London, vol. 41, 1880, p. 189. 
3 Lauth: Bull. Soc. chim., Paris, vol. 46, 1886, p. 786. 
4 Le Chatelier: Ibid., vol.47, 1887, p. 300. 
s Thomas Carnelley: Melting aud boiling point tables; London, Harrison & Sons, 
two vols., 1885. 
6 Landolt u. Bornstein: Physikalisch-ehemische Tabellen, Berlin, Julius Springer, 
1883. 
7 Guyton-Morveau : Ann. ch. et phys., vol. 46, 1803, p. 276; vol. 73, 1810, p. 254 ; vol. 
74, 1810, pp. 18, 129 ; vol. 90, 1814, pp. 113, 225. 
8 Schwarz: Bull. Soc. Mulhause, 1827, p. 22; Pogg. Ann., vol. 14, 1828, p. 530. 
9 Coulomb : Pogg. Ann., vol. 14, 1828, p. 530. 
10 Clement and Desormes: Dingler's Jour., vol. 33, 1829, p. 145. 
11 Anonymous: Pogg. Ann. 2d series vol. 39", 1836, p. 518. 
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