8 WILLCOX : 



names of magnetite and hematite. The exception noted 

 above applies to the ore which is composed of iron combined 

 with carbonic acid, and known as siderite. 



A small portion of carbon, when combined with iron, 

 effects a remarkable change in its character ; in fact, the 

 latter is converted into steel ; and the hardness of steel, of the 

 several grades, is chiefly due to the amount of carbon com- 

 bined with it. There are several metals which, when com- 

 bined with steel, make the latter harder and tougher, especi- 

 ally the metal nickel. Some of the modern armor plates for 

 battle ships are made of this combination. Some of the 

 oxides of iron are so deeply colored red that they are used as 

 paint. And some of the minerals containing iron are colored 

 in proportion to the amount of iron in them. 



Sulphur, one of the useful elements, is not found in the free 

 state in many places. The most important localit}^ for sulphur 

 is on the island of Sicily, where it often occurs in beautiful 

 and brilliant yellow crystals. Sulphur combines easily with 

 oxygen, burning with fire and resulting in sulphurous or sul- 

 phuric acid gas, of which vitriol is made. Sulphur is subli- 

 mated or converted into vapor at a low degree of heat. It 

 performs an important function in nature in arresting many of 

 the metallic substances when dissolved in water and combining 

 with them ; otherwise they would be carried to the sea and lost. 

 Man}^ mineral beds and veins owe their existence to this process. 



The ores of many of the metals consist of such metals 

 combined with sulphur, including the following as some of 

 them, viz : Silver, copper, zinc, tin, arsenic, mercury, anti- 

 mony and msLuy others. Sulphur is found sometimes in lar,ye 

 deposits combined with iron, forming iron pyrites. Iron 

 pyrites is a mineral often occurring in beautiful cubical crys- 

 tals, and in many modifications of the cubical system. In 

 color it resembles gold. It is the ore in which the gold in 

 Colorado is chiefly found. Sulphur is one of the necessary 

 components of animals and plants. It is found quite a])und- 

 unth' in hiir, feathers and eggs pnrlienlarlw 



