1894 



THE MICROSCOPE. 



41 



Fahr. and in three days he found 21 of the 23 flasks 

 opened in the hay mow crowded with life. After three 

 weeks of exactly the same conditions to which the 23 

 were subjected not one of the 27 had given way. The 

 inference here is that it was not the air of the loft but 

 something present in the air which produced the results 

 observed in the 23 flasks. 



For nearly 10 years, as he was able, Professor Tyndall 

 was engaged in a study of the efl'ects of radiant heat and 



I 



> 



=s 



light upon gasses and his studies led to an important dis- 

 covery. In a beam which illuminated the dust in his 

 laboratory, he placed an ignited spirit lamp and around 

 its rim were seen rims of darkness like an intensely black 

 smoke but which was proved not to be smoke for a hot 

 poker and a smokeless alcohol lamp produced the same 

 appearance. The blackness was that of stellar space or 

 the blackness resulting from the absence of all matter 

 which could scatter light. The flame destroyed the float- 



