MAGNITUDE AND MINUTENESS. 



17. The optical investigations of Newton disclosed some aston- 

 ishing examples of the^ninute divisibility of matter. 



A soap-bubble, as it floats in the light of the sun reflects to the 

 eye an endless variety of the most gorgeous tints of colour. 

 Newton showed, that to each of these tints corresponds a certain 

 thickness of the substance forming the bubble ; in fact, he showed 

 in general, that all transparent substances, when reduced to a 

 certain degree of tenuity, would reflect these colours. 



Near the highest point of the bubble, just before it bursts, is 

 always observed a spot which reflects no colour and appears black. 

 Newton showed that the thickness of the bubble at this black 

 point was the 2,500000th patt of an inch! Now, as the bubble 

 at this point possesses the properties of water as essentially as 

 does the Atlantic Ocean, it follows, that the ultimate molecules 

 forming water must have less dimensions than this thickness. 



18. The same optical experiments were extended to the organic 

 world, and it was shown, that the wings of insects which reflect 

 beautiful tints resembling mother-of-pearl owe that quality to 

 their extreme tenuity. 



Some of these are so thin that 50000 placed one upon the 

 other would not form a heap of more than a quarter of an inch in 

 height ! 



19. The natural filaments of wool, silk, and fur afford striking 

 examples of the minute divisibility of organised matter. The 

 following numbers show how many filaments of each of the 

 annexed substances placed in contact, side by side, would be 

 necessary to cover an inch : 



Coarse wool 500 



Fine Merino wool 1250 



Silk 2500 



The hairs of the finest furs, such as beaver and ermine, hold 

 a place between the filaments of Merino and silk, and the wools 

 in general have a fineness between that of Merino and coarse 

 wool. 



All these objects are sensible to the touch. 



It will be remembered that they are compound textures, having 

 a particular structure, each containing very different elements, 

 which are prepared by the processes of nutrition and secretion. 



20. Microscopic observations have shown that blood is not as it 

 appears to the naked eye an uniformly red liquid, but that it is a 

 clear transparent colourless liquid, in which float countless numbers 

 of thin, flat, red particles of a round or oval shape. The diameter 

 of these red particles in the human blood, is the 3500th part of 

 an inch. In certain species of animals it is much smaller, and 



200 



