CHAPTER V 

 BLUE WATER 



MOST people know and admire the splendid 

 expanse of blue colour offered by the clear sea 

 water on many parts of our coasts, and by that 

 of lakes at home and abroad. I find that there is still 

 a sort of a fixed determination not to believe that this 

 colour is due (as it is) to the actual blue colour of pure 

 water. Pure, transparent water is blue. Those who 

 think they know better will point to a glass of pure 

 water, hold it up to the light, and affirm that it is colour- 

 less. But this apparent colourlessness is due to the 

 small breadth of water in the glass through which the 

 light passes. It is definitely ascertained that if water 

 as pure and as free from either dissolved or suspended 

 matter as it is possible to make it (by distillation and 

 the use of vessels not acted upon by water) be made to 

 fill an opaque tube 15 ft. long, closed at each end by 

 a transparent plate, and then a beam of light be made 

 to traverse the length of the tube, so that the eye receives 

 the light after it has passed through this length of 15 ft. 

 of water, the colour of the light is a strong blue. Water 

 is blue in virtue of its own molecular character, just as 

 sulphate of copper is. Liquid oxygen, prepared by the 

 use of intense cold, is also transparent blue, and the 

 peculiar condensed form of oxygen known as " ozone " is, 

 when liquefied, of a darker or stronger blue than oxygen. 

 At one time (some thirty years ago) there was still 



