426 NATURE 8 TEACHINGS. 



an expensive article, and therefore, instead of being thrown 

 away, the discoloured spirit is placed in the still, and repro- 

 duced in a clean and transparent state. 



Nature affords innumerable examples of distillation, the chief 

 of which are the Dewdrops which have already been mentioned. 

 During the daytime the air is full of moisture drawn by the 

 sunbeams from ocean. "We cannot see it, but it is there, and 

 when the chill of night cools the various trees, herbage, and 

 other such objects, the aerial moisture is condensed upon them, 

 which is then known by the name of Dew. 



On the left hand of the illustration are shown the tiny Dew- 

 drops as hanging on the slight threads of a spider's web, and 

 collected in larger drops upon a leaf. 



THERE are many other familiar examples of the principle of 

 condensation, the commonest of which is the so-called steam as 

 it pours from the spout of a kettle. In point of fact, it is not 

 steam at all, but only water condensed into very small drops. 

 At the orifice of the kettle it is quite invisible, but when it 

 passes into the air, and is condensed, the tiny globules become 

 visible. The same fact may be noticed in the Napier's Coffee 

 Machine, which has already been mentioned. When the water 

 is boiling in the glass globe no steam is visible, though the 

 upper portion of the globe is entirely filled by it. But, no 

 sooner is the cork removed, and the steam allowed to escape, 

 than it at once becomes visible as a white cloud, being, indeed, 

 a miniature copy of the rain-clouds that float above us. 



THEN there is that mostly invisible passage of liquid through 

 the multitudinous pores of the body, which is generally known 

 as perspiration. It is invisible in warm weather, but on a cold 

 day is as visible as a rain cloud. 



The Turkish Bath affords a good example of this fact. Some- 

 times the hottest room attains a temperature of 250 or more, 

 water boiling at 212. When a bather goes into that room, 

 he appears to have a perfectly dry skin, the moisture being in 

 the form of invisible steam, and swept off as soon as it is gene- 

 rated. 



But, if he passes at once into the cold room, he is so enveloped 

 in vapour that for a few moments he is wrapped in it as in a 



