126 APPLIED SCIENCE 



130. Mixtures and Compounds. The great variety of 

 solids, liquids, and gaseous substances that are used in one 

 form or another in every-day industrial operations may be 

 divided into mixtures, compounds, and elements. 



FIG. 66. Taking Test Borings of Pig Iron. 

 Various parts of the bar are drilled and the 

 borings thus obtained are mixed and analyzed. 



When two or more substances are put together, the result 

 is called a mixture. While the mixture may differ in some 

 ways from each of the substances that compose it, no new 

 compound is formed, and the original substances may be 

 separated by mechanical means. We can mix substances 

 in any proportion. Gunpowder, for example, is a mixture of 

 sulphur, carbon, and saltpeter. Each one of these ingredients 

 may be separated from the others. Water, for example, 

 will separate the saltpeter. 



A compound, the smallest part of which is called a molecule, 

 is a substance composed of two or more special substances 

 called elements, which are combined in definite proportions. 

 The new substance formed as the result is generally unlike 

 either of the elements which compose it. For example, by 

 passing an electric current through a mixture of 2 parts of 



