78 SCIENTIFIC NEWSj 



gree proportioned to their illuminating power, the greatest 

 effect on the thermometer being produced half an inch be- 

 yond the visible spectrum. Indeed Dr. Herschel*8 several 

 papers, published in the Ph. Trans, for 1800, render it, at 

 least, extremely probable, that the colorific rays themselves 

 do not affect the temperature of bodies. Now it is matter 

 of little consequence, whether we terra the invisible heat- 

 making rays light or caloric. If we are pleased to call them 

 light, we must yet admit, that they are invisible ; and can- 

 not therefore, because the candle's flame is luminous, object 

 to its being used as a source of heat in experiments on ra- 

 diant caloric. 

 or may be It may still be urged, that, although light, strictly so 



der bodies called, is not possessed of a heating property, yet its asso- 

 more pervious ciation with caloric may cause this agent to pass through 

 media, which under other circumstances would be impervi- 

 ous to it. It is only possible to conceive the transmission of 

 caloric through dense media to be facilitated by its associa- 

 tion with light, by supposing an attraction to be exerted by 

 these fluids for each other. But all the phenomena of 

 phosphorescence show, that the very opposite to attraction, 

 namely repulsion, prevails between light and caloric. All 

 objections, however, to the source of heat will be removed, 

 when we consider, that the experiments in which the flask 

 with a boiling mixture of sulphuric acid and water was used 

 afforded results similar to those obtained from the combus- 

 tion of a candle. 



(To be concluded in our next. J 

 +—> ■ ■ , | i 



SCIENTIFIC NEWS. 



AWernerian Natural History Society. 

 T the meeting of this Society on the 10th of March, 

 Siroatian the Rev. Dr. Macknight read a paper on the mineralogy of 



Strontian and Ben Nevis. The rocks which compose the 

 districts of Strontian are mica slate, gneiss, and granite; 

 and the lead-glance, which occurs in gneis6, is associated 

 with iron-pyrites, cross-stone, calc-spar, foliated zeolite, 

 andBenNe\Lv strontian, and heavy-spar. Ben Nevis is an overlying mas- 

 sive formation, which rests on gneiss and mica-slate, ap- 

 proaching in some places to clay-slate. In this formation, 

 compact feldspar is the leading ingredient. The inferior 

 Uias* consists of sieuite, passing from the simple-gianular to- 



the 



