Literature and Commerce. 8 1 



thermometer. This excellent philosopher, to whom, as a 

 learned foreigner has observed, " Nature takes delight in 

 revealing her secrets," has also first discovered, and Dr. 

 Ingenhouse, treading in his paths, has more completely 

 demonstrated the method by which Nature makes use of 

 the leaves of vegetables to purify the atmosphere, when 

 contaminated with putrid or phlogistic vapours. When in 

 this state, every leaf acts as a strainer to the air, imbibing 

 and applying to the nurture of the plant such parts as are 

 unfit for animal respiration, and throwing it out again, thus 

 filtered and suited to act again as a menstruum for the 

 phlogiston, which is continually evolving by the breathing of 

 animals, the corruption of vegetables, and by the many 

 various processes which are by nature and by art continually 

 carrying on. 



' Electricity is another branch of science which has 

 afforded great light to the operations of nature. A know- 

 ledge of its leading principles, and a dexterity in making a 

 number of entertaining experiments, may be attained by 

 moderate application, and thereby a field of amusement 

 opened to the mind, at an easy expense of time and 

 money. 



4 To obtain a perfect acquaintance with the science of 

 optics, much attention and close application would be re- 

 quisite. Such a knowledge of it, however, as is sufficient 

 for general purposes, is easily arrived at. The nature of 

 the reflection and refraction of the rays of light, of vision, 

 and of colours, the properties of lenses, are useful and 

 entertaining objects of inquiry. But the very minute divi- 

 sibility of the rays of light fills the mind with astonish- 

 ment. When we are informed that there proceeds more 

 than 6,000,000,000,000 times as many particles of light 



G 



