818 FRAGMENTS OF SCIENCE 



disintegrating his tissues, or poisoning him by the decom- 

 positions incident to its growtk. 



During the ten years extending from 1859 to 1869, re- 

 searches on radiant heat in its relations to the gaseous 

 form of matter occupied my continual attention. When 

 air was experimented on, I had to cleanse it effectually 

 of floating matter, and while doing so I was surprised to 

 notice that, at the ordinary rate of transfer, such matter 

 passed freely through alkalies, acids, alcohols, and ethers. 

 The eye being kept sensitive by darkness, a concentrated 

 beam of light was found to be a most searching test for 

 suspended matter both in water and in air — a test indeed 

 indefinitely more searching and severe than that furnished 

 by the most powerful microscope. With the aid of such 

 a beam I examined air filtered by cotton- wool; air long 

 kept free from agitation, so as to allow the floating matter 

 to subside; calcined air, and air filtered by the deeper 

 cells of the human lungs. In all cases the correspondence 

 between my experiments and those of Schroeder, Pasteur, 

 and Lister in regard to spontaneous generation was per- 

 fect. The air which they found inoperative was proved 

 by the luminous beam to be optically pure and therefore 

 germless. Having worked at the subject both by experi- 

 ment and reflection, on Friday evening, January 21, 1870, 

 I brought it before the members of the Royal Institution. 

 Two or three months subsequently, for sufficient practical 

 reasons, I ventured to direct public attention to the sub- 

 ject in a letter to the *' Times." Such was my first contact 

 with this important question. 



This letter, I believe, gave occasion for the first public 

 utterance of Dr. Bastian in relation to this subject. He 



