224 ANSWEES TO PRACTICAL QUESTIONS 



of the cream the milk reflects the blue light in excess 

 of the others. 



63. What would be the effect of filling the basin, in the 

 experiment shown in Fig. 147, with salt water! 



The water would be made denser and its refractive 

 power would be correspondingly increased. 



(Compare Physics, p. 268, note.) 



64. Why is not the image of the sun in water at mid- 

 day so bright as near sunset ? 



(See Physics, p. 151, ad note.) 



65. Why is the rainbow always opposite the sun ? 



(See Physics, p. 166.) 



HEAT. 



203. 1-54. (See Key, pp. 40-47.) With regard to 

 Question 23 there is much difference of opinion. Many 

 authorities think that temperature, and not moisture, is 

 the chief factor in producing barometric changes. 



(See Muller, Komische Physik, 637.) 



55. Why will "fanning" cool the face? 



It brings in contact with the face a current of fresh 

 and generally cooler air. 



(See Physics, p. 191.) 



56. How are safes made fire-proof 1 



By filling the space between the inner and the outer 

 iron-plates with a non-conducting material, as plaster, 

 etc., the safe is rendered nearly fire-proof. In one form 



