THE EGG 31 



to be able to recognize, before using and breaking it, 

 whether an egg is fresh or stale. I have seen the 

 following means used, which would seem very 

 strange if what I have just told you about the air- 

 chamber did not furnish the explanation. The tip of 

 the tongue is applied to the large end. If the egg is 

 fresh a slight impression of coolness can be felt; if 

 stale, the tongue remains warm. This little mystery 

 is based on the different manner of behavior of li- 

 quids and gases when brought into contact with heat. 

 Water and liquids in general take away rather 

 quickly the heat of the bodies with which they come 

 in contact ; air and other gases, on the contrary, take 

 it away very slowly. That is why water seems cold 

 when we plunge our hand into it, while the air, lower 

 in temperature, seems warm by comparison. In 

 reality, if both be of the same temperature, air and 

 water give us different sensations: water is cool to 

 us because it draws our heat away; air warm because 

 it does not take away that same heat. So if the egg 

 is fresh, and consequently the shell completely filled, 

 the tip. of the tongue applied to the large end feels 

 the same sensation as comes from contact with li- 

 quids ; that is to say, a feeling of coolness. But if 

 the egg is stale, an air-chamber has formed and the 

 resulting sensation is that produced by contact with 

 a gas ; that is to say, a sensation of warmth, since 

 the tongue loses none of its natural heat." 



"That is certainly a curious test," said Jules, 

 "and I shall make it a point to carry it out at the next 

 opportunity. ' ' 



