162 LIGHT AND COLOURS. [Lesson XXV. 



different Colours, as ihey arise in the bubble; and 

 they will perceive first red, then perhaps blue, or 

 orange, green, indigo, violet, and in short, here 

 and there, all manner of Colours j even white and 



perhaps at last a sort of black*. 



It 



* The following curious and useful remarks on the dif- 

 ferent degrees of heat imbibed from the sun's rays, &c. by 

 cloths of different Colours, were extracted from " Experi- 

 ments and Observations" by that famous American philo- 

 sopher and politician, Dr. B, Franklin. 



" First, let me mention an experiment you may easily make 

 yourself. Walk but a quarter of an hour in your garden 

 when the sun shines, with a part of your dress white, and a 

 part black ; then apply your hand to the,m alternately, and 

 you will find a very great difference in their warmth. The 

 black will be quite hot to the touch, the white still cool. 



" Another. Try to fin paper with a burning glass. If it be 

 white, you will not easily burn it; but if you bring the focus 

 to a black spot, or upon letters written or printed, the paper 

 will immediately be on fire under the letters. 



" Thus Fullers and Dyers find black cloths of equal thick* 

 ness with white ones, and hung out equally wet, dry in the 

 sun much sooner than the white, being more readily heated 

 by the sun's rays. It is the same before, a fire; the heat of 

 which sooner penetrates black stockings thai) white ones, and 

 is so apt sooner to burn a man's shins. Also beer much 

 6 ooner warms in a black mug set before the fire, than in a 

 white one, or in a bright silver tankard. 



" My experiment was this: 1 took a number of little square 

 pieces of broad cloth from a tailors pattern card, of various 

 colours. There were black, deep blue, lighter blue, green, 

 purple, rf d, yellow, white, and other Colours, or shades of 

 Colours. I laid them all out upon the snow in a bright sun- 

 shin v morning. In a few hours (I cannot now be exact as to 

 tin.- time; the black, being warmed most by the sun, was sunk so 

 low as to be below the stroke of the sun's rays ; the dark blue 

 almost as low, the lighter blue not quite so low a the dark . 



the 



