26 FROM AN EASY CHAIR 



surface in the form of " pipes " 100 yards to half a mile 

 in diameter. It has long been known that at very high 

 temperatures (4,000 deg. Centigrade) the metal iron 

 dissolves carbon. The late Professor Moissan, of Paris, 

 obtained artificial diamonds by suddenly cooling the 

 iron in which carbon was dissolved by plunging the 

 crucible into water. The outer shell of iron cools and 

 forms a tightly closed shell enclosing the still liquid 

 core. As this core cools it tends to expand, and thus 

 produces an enormous pressure. The melted carbon 

 cooling under this pressure assumes the crystalline 

 colourless form known as diamond. There is good 

 reason to believe that diamonds are formed, or have 

 been formed, in association with metallic iron in a 

 similar way, on a large scale, in great depths of the 

 earth's crust, and are shot up to the surface with other 

 debris in the volcanic steam mud which is the " blue 

 ground."" 



A few diamonds of small size have been found in the 

 Ural Mountains, otherwise they are not natural products 

 of the northern hemisphere. It is in India, Australia, 

 South America, and South Africa that they are picked 

 up, either in beds of streams, or in peculiar volcanic mud, 

 or embedded in even harder rock. Many are in a 

 condition of severe strain when found, and contain 

 minute cavities filled with liquid carbonic acid. They 

 are liable, in consequence, to break or even fly into 

 powder when warmed by the hand or struck. Though 

 usually colourless, diamonds may be yellow, green, blue, 

 or red, and the rays of radium cause colourless diamonds 

 to become coloured. Some diamonds, but not all, are 

 phosphorescent that is to say, like the well-known 

 luminous paint after exposure to strong light they 

 acquire the power of shining themselves for a certain 

 time when removed to a dark chamber. And the 

 curious thing is that, though themselves colourless, some 

 give out blue, some green, some yellow, and some red 



