i(j6 Mr. Morgan's Ohfervatlom and Experiments ort 



The moH fingular phenomenon attending a burning body 

 iS, perhaps, the red appearance it aflumes in its lafl: ftage of 

 coiribiiiLlon. The preceding fatls and obiervations may, I 

 think, help us to explain it. 



1. After a body has continued to burn for fome time, its 

 external lurface is to be regarded as having loft a great portion 

 if not the whole of thofe rays which the firfl application of 

 heat was able to feparat'e. Bat thefe rays w^ere the indigo, the 

 violet, the blue, and perhaps the green. Nothing, therefore, will 

 remain to be fepa rated, buttbe yellow, the orange, and the red, 

 C^onfequently, the combuftion of the body, in its lafl: ftate of de- 

 compolition, can afllime no other than a reddifli appearance. But 



2. Let us con-fide r the external fur face of the combuflible 

 as annexed, to an inner furfaee, which may be partly, but not fo 

 perfectly decompoled as itfelf : for the violence of the heat will 

 be found to lelien in its effeds the nearer it approaches to the 

 center of the fubftance which is expofed to it. Hence we are 

 to confider the parts which are juft covered by the external fur- 

 face as having loft lefs of their component light than the exter- 

 nal furfaee itfelf. Or the former may retain the green rays 

 when the latter has loft both indigo, violet, blue, and green. 



3. Thofe parts which are nearer the center of the body 

 than either of the preceding muft, as they are further from 

 the greateft violence of the heat, have loft proportionably 

 fewer of tlieir rays. Or w^hile the more external parts may 

 have loft all but the red, thefe may have loft only the indigo 

 snd viokt. 



4» The moil central parts may be unafFeded by the heat ; 

 and whenever the fire does reach thefe parts, they will imme- 

 diately difcharge their indigo rays, and be decompofed in the 



gradual 



