128 Introduction to the Study of Science 



The observance of these conditions will insure better control of 

 fire, more economical consumption of fuel, and it should 

 stimulate to a fuller utilization of the heat produced. 



49. Forms of carbon. Soot or lampblack is produced on a 

 large scale for commerce from natural gas, coal gas, or petroleum. 

 It is deposited in a relatively pure form on the inside of the 

 retorts, in which coal is distilled for illuminating gas. Its 

 familiar uses are in making black paints, printing inks, and shoe 

 polish. It is made into carbons used in electric arc lights, and 

 into the carbon plates for dry batteries. Examine the carbon 

 of a dry battery. 



Diamonds and graphite. Interesting forms of carbon are 

 found in the diamond and graphite. The diamond when 

 burned in a closed retort becomes like graphite ; when heated 

 in oxygen it is burned to carbon dioxid. Carbon may be 

 changed by a very high temperature (about 3000 C.) and 

 enormous pressure into diamonds. (Consult an encyclopedia 

 for information about Henry Moissan and his work in produc- 

 ing diamonds.) Graphite is used in making lead pencils, in 

 paints which are especially protective against rust, in making 

 crucibles and other containers to withstand very high tempera- 

 tures, and as a lubricant. 



Charcoal made from wood is almost pure carbon. In its 

 modern manufacture, wood is heated in closed retorts with 

 no access of air. Certain by-products are secured, such as wood 

 alcohol and acetic acid, both being of great importance in 

 chemical manufactures. Combustible gases are also collected 

 and piped to the furnace as fuel. The process is known as 

 wood distillation. 



Coke. Carbon constitutes a large percentage of coal, lignite, 

 and peat. Coke which is almost pure carbon, is obtained from 

 coal heated in much the same manner as wood for charcoal. 

 Coke burns at a high temperature with little flame and no smoke. 



50. Carbon compounds. Carbon is found in many com- 

 pounds of great importance. Carbon and hydrogen combined 



