—— 
259 
Solid bodies begin to be— 
1. A little lower than a Tron, red hot, visible in 
dull red visible in dark a Fae er 932° 
the dark ... ..» 320° 608° Iron red hot, visible in 
2. Dull red in the dark 335° 670° daylight ... Pop eee ee hs 
3. Very dull red visible Cherryredheatofiron ... 1292° 
in the dark .. 360° 680° Full red heat of iron... 1472° 
4. Of adecided red heat 380° 716° White heatof iron... ... 2372° 
5. Bright red ... .. 400° 784° 
(Sorby) (Carnelley) 
In the course of the discussion in the preceding Paper on 
granite, &c., some degrees of temperature were cited, and are 
approximately as below :— 
1. Probable mean temperature attained in Newnham 
Church by granite, 320° C. 
2. In Experiment I, first described, when granite was 
brought to cherry red, 900° C. 
_ 8. In Experiment III, the degree to which the granite 
was raised was orange red, 1000° C. 
4, In the second trial the granite reached to a low white 
degree of heat, 1200° C. 
5. The granulites in tanks at the Dresden Glass Works 
melt at about 1100° C. : 
In this appendix on the higher temperatures, are inserted 
the approximate values of certain colour names of temperatures, 
or states of heat; for some of these data the writer desires to 
acknowledge his deep sense of the favour so generously given 
by Dr Sorby, F.R.S., and Professor Carnelley, D. Se. of Uni- 
versity College, Dundee, F.R.S., both eminent as specialists in all 
that pertains to the action of heat and this branch of research. 
