Q15 EXPERIMENTS ON LIGHT. 



diftinftata The experiment muft be made at a very fmall diflance from 

 little diftance, ^^^ -^^^ ^^^j ^,f f^^^ -^^^^^^ f^^j. example, to diftinguifti the 

 as 4 inches, but r » r ' o 



confounded to- two fpedrums, which become confounded together in propor- 



gedi^i when i\q„ ^q thejr diftance from the prifm. No doubt this is the 



farther oiF. ,- , , , . /- i r i i • r 



reafon why the phenomenon has lo long elcaped the notice ot 



And the chemi- philofophers. This obfervation was accompanied by another, 

 cai rays may be f^jji niore important; namelv, that the chemical rays may be 



completely fe- i , /• , ,• 1 , , rr i • ri i 



parated from the completely leparated Irom the coloured rays. It the mvnible 



coloured, with- f^ys of the violet fide be made to fall on the red part of the fo- 



them. ^^'^ fpeftrum, the procefs of oxidasioii may be completely fuf- 



pended there, and even difoxidation produced, without de- 



ftroying the red colour; and by means of feveral prifms we 



may even feparate all the coloured rays from the chemical 



So that we may rays. We may thus produce a coloured fpeftrum devoid of 



foureTf e(a° chemical a6lion ; and a feries of chemical rays, analogous to 



devoid of chemi- the fpedrum, without any mixture of coloured rays. 



caladion. -yy^g have not yel any accurate experiments, to determine 



rays have not whether the calorific rays be likewife feparable from the others, 



been p oved to particularly from the chemical rays: but the comparifon of dif- 



be feparabie '. . ... , ^ i i , 



from the che- lerent experiments madem winter and lummer, when the de- 

 mical; but it grees of heat are different, though no difference in the force of 

 they are'^finw ^^^ chemical rays at different feafons has been obferved, lead 

 the former difler to a belief that the calorific rays are feparable from the chemi- 



in degree in i 



wintei and fum« 



mer, the latter It may be aflced, why the different rays found in light fre- 



^, ""'^; quently accompany each other, though they can fubfift fepa- 



That they ac- ^ , -^ , , • n • , , i /- . . 



company each rately : and this queltion no doubt maybe aniwered, when 



other, though vvo are able to fay, why the diflTerent functions of electricity 

 greater d'ifficulty accompany each other, though they likewife are feparable. 



than attends 



dethicity. ■ 



xviir. 



On spontaneous Injlammatiom. Bj/G. C. Bartholdi, Fro- 



feff'r of Phyfic and Chejnijlrjj* 



Definition of ^PONTANEOUS inflammation is (hat which is manifefted 

 fpontaneous in acombuftible body, without the immediate confad of any 

 "~ ignited matter. 



* From the Annales de Chimie, Vol. XLVIII. p. 249, or 

 No. 144t 



Thefe 



inflammation. 



