382 Messrs. Wanklyn and Cooper on the Determination 



the flame-temperature, and would therefore take place on all 

 sides of the rod. 



(3) A strongly heated surface also becomes covered with a 

 deposit of soot. This would not be possible if the deposit 

 were the result of the cooling action of the surface upon the 

 flame. 



(4) The carbon particles present in the luminous flame 

 become visible ivhen the flame is caused to rush against another 



flame or against a heated surface. The separated particles are 

 rolled together into larger masses, so that the luminous mantle 

 becomes filled with numerous glowing points. The soot of such 

 a flame is very coarse-grained. 



(5) The luminous mantle of a flame is not altogether 

 transparent : the thicker the flame-layer and the greater the 

 number of solid particles contained therein, the less trans- 

 parent does it become. The transparency of a luminous flame 

 is no greater than that of the {approximately) equally thick 

 stratum of soot which rises from the flame of burning turpen- 

 tine^ and which is universally alloived to contain many solid 

 carbon particles. The luminous* flame of hydrogen, containing 

 solid chromic oxide, is as transparent as the hydrocarbon- 

 flame. 



(6) Those flames which undoubtedly owe their luminosity 

 to the presence of finely divided solid matter, produce charac- 

 teristic shadows when viewed in sunlight. The only luminous 

 flames which do not produce true shadows are those which 

 consist of glowing vapours and gases. Luminous hydrocarbon- 

 flames produce strongly marked shadows in sunlight ; these 

 flames therefore contain finely divided solid matter. That this 



solid matter can be nothing but carbon is evident from the 

 fact that other, substances, capable of remaining solid at the 

 temperature of these flames, are absent. 



These proofs are, I think, sufficient to convince every one 

 that the luminous flames of hydrocarbons actually contain solid 

 carbon particles. 



Darmstadt, Chemisches Laboratorium des 

 P oly teclinicums . 



LT. On a Method of determining the Amount of Proteine 

 Compounds in Vegetable Substances. By J. Alfred Wank- 

 lyn, Corresponding Member of the Royal Bavarian Academy 

 of Sciences, and W. J. Cooper *. 

 rjlHE physiological doctrine that the animal does not pro- 

 J- duce proteine compounds, but simply transforms those 

 proteine substances which it has taken in as food, lends great 

 * Communicated by the Authors. 



