38S 



Prof. Draper on the Production of Light by Heat 



TABLE IV. 



Relative -proportions of water and solid constituents in 1000 parts. 



Water, .... 

 Sulphate of lime, 

 Chlorid of calcium, 

 Chlorid of sodium, . 

 Chlorid of magnesium, , 

 Carbonate of lime. . 

 Carbonate of magnesia, . 

 Alumina and iron, 

 Alumina, 

 Silica, .... 



Carbonate of soda equiv. to 

 Magnesia combined with 

 Lime, .... 

 L 



crenate, 

 do. 



No. 1. 



999-289 

 •069 

 •112 

 •191 

 041 

 •225 

 •0J9 

 •004 



•018 

 •022 



No, 2. 



No 3. 



No. 4. i No. 5. 



999-449 999-G69 999-364 



OSS 



010 



061 

 •070 



023 

 131 



038 



060 

 109 

 013 



046 



030 

 039 



022 

 021 



079 



014 

 014 

 119 



076 



excess. 



081 

 148 



004 



004 

 235 

 044 

 023 

 018 



998-81 >' 

 •08 



•179 



•267 



•041 



' 151 



traces. 



•010 

 •267 



178 



1000-000'1000-000 l< 1(10-004 1000-000 1000-dOO 



Vale College Laboratory, New Haven, Aug. 9th, 1847. 





Art. XXXV. — On the Production of Light by Heat; by John 

 William Draper, M.D., Professor of Chemistry in the Univer- 

 sity of New York * 



Although the phenomenon of the production of light by all 



solid bodies, when their temperature is raised to a certain degree, 



is one of the most familiar in chemistry, no person so far as I 



know has hitherto attempted a critical investigation of it. The 



difficulties environing the inquiry are so great, that even among 



the most eminent philosophers a diversity of opinion has prevailed 



respecting some of the leading facts. Thus Sir Isaac Newton 



fixed the temperature at which bodies become self-luminous at 



635°, Sir Humphry Davy at 812°, Mr. Wedgwood at 947°, and 



Mr. Darnell at 980°. As respects the nature of the light emitted 



there are similar contradictions. In some philosophical works ol 



considerable repute, it is stated that when a solid begins to shine 



it first emits red and then white rays ; in others it is asserted that 



a mixture of blue and red light is the first that appears. 



I have succeeded in escaping or overcoming many of the diffi- 

 culties of this problem, and have arrived at satisfactory solutions 

 of the main nnint.s • and ^ tUa ov™..;,™™** «««r tn hp described 



points 



perhaps 



^v* w duuw Buuwijg atiu pernaps unexpected analogue u»»~- 

 light and heat, they commend themselves to our attention as 

 having a bearing on the question of the identity of those impon- 

 derable principles. It is known that heretofore I have been lea 



* Extracted from the London, Edinburgh 



an 



d Dublin Philosophical Maga»«>«» 



