50 Things not generally Known. 



staiit remove it and the vessel from the fire. Then press the cork fur- 

 ther into the neck of the phial, and cover it thickly with sealing-wax ; 

 and when the contents are cold, a perfect vacuum will be formed within 

 the bottle, much better, indeed, than can be produced by the best- 

 constructed air-pump. 



To form a bubble, hold the bottle horizontally in both hands, and 

 give it a sudden upward motion, which will throw the liquid into a wave, 

 whose crest touching the upper interior surface of the phial, the tena- 

 city of the liquid will cause a film to be retained all round the phial. Next 

 place the phial on its bottom ; when the film will form a section of the 

 cylinder, being nearly but never quite horizontal. The tilm will be now 

 colourless, since it reflects all the light which falls upon it. By re- 

 maining at rest for a minute or two, minute currents of lather will de- 

 scend by their gravitating force down the inclined plane formed by the 

 film, the upper part of which thus becomes drained to the necessary 

 thinness ; and this is the part to be observed. 



Several concentric segments of coloured rings are produced ; 

 the colours, beginning from the top, being as follows : 



1st order : Black, white, yellow, orange, red. 



2d order : Purple, blue, white, yellow, red. 



%d order : Purple, blue, green, yellowish-green, white, red. 



4th order : Purple, blue, green, white, red. 



5th order : Greenish-blue, very pale red. 



6th order : Greenish-blue, pink. 



7th order : Greenish-blue, pink. 



As the segments advance they get broader, while the film be- 

 comes thinner and thinner. The several orders disappear up- 

 wards as the film becomes too thin to reflect their colours, 

 until the first order alone remains, occupying the whole surface 

 of the film. Of this order the red disappears first, then the 

 orange, and lastly the yellow. The film is now divided by a 

 line into two nearly equal portions, one black and the other 

 white. This remains for some time ; at length the film becomes 

 too thin to hold together, and then vanishes. The colours are 

 not faint and imperfect, but well defined, glowing with gor- 

 geous hues, or melting into tints so exquisite as to have no 

 rival through the whole circle of the arts. We quote these de- 

 tails from Mr. Tomlinson's excellent Student's Manual of Natu- 

 ral Philosophy. 



We find the following anecdote related of Newton at the above 

 period. When Sir Isaac changed his residence, and went to live in 

 St. Martin's Street, Leicester Square, his next-door neighbour was a 

 widow lady, who was much puzzled by the little she obsei'ved of the 

 habits of the philosopher. A Fellow of the Royal Society called upon 

 her one day, when, among her domestic news, she mentioned that some 

 one had come to reside in the adjoining house who, she felt certain, was 

 a poor crazy gentleman, " because," she continued, " he diverts himself 

 in the oddest way imaginable. Every morning, when the sun shines so 

 brightly that we are obliged to draw the window-blinds, he takes his 

 seat on a little stool before a tub of soapsuds, and occupies himself for 

 hours blowing soap-bubbles through a common clay -pipe, which bubbles 



