APPENDIX 159 



synthetic, when combinations are made, and analytic 

 Avhen they are broken up. The force which makes two 

 or more elements -unite to form a new mass of matter is 

 called chemical affinity and acts on different elements 

 with varying degrees of violence at inappreciable dis- 

 tances. 



" Chemistry is that science which treats of the com- 

 position of matter and the changes in composition." 

 (Bliss and Olive). 



Elements. Those substances which have resisted 

 every effort to reduce .them to simpler forms are known 

 as elements. Iron, silver, gold, potash, soda, oxygen, 

 etc., are examples of these primary bodies. A table of 

 elements with their atomic weights and symbols is ap- 

 pended. To save space and time, the whole name of an 

 element is not written when a chemical combination is 

 to be expressed by a formula, but the first letter of the 

 name of the element is used as a capital, followed by a 

 small letter taken from the name when the names of 

 two elements begin with the same letter. Thus H is 

 the symbol of hydrogen and Hg the symbol of mercury, 

 the official name of which is hydrargyrum; or Fe (fer- 

 rum) iron, while F stands for fluorine. Elements can 

 not be divided into simpler bodies, but every element 

 is composed of invisible particles called atoms and as 

 atoms, however small, none the less have weight, the 

 symbols of the elements represent an atom of that 

 element which has a weight, as compared with some 

 other element used as a standard, called its atomic 

 weight. As hydrogen is the lightest of known elements, 

 it has been selected as the standard. The symbol "H" 

 means one atom of hydrogen having a weight repre- 

 sented by the figure 1, while the volume of oxygen of 

 the same cubic measure, Q the, volume of hydrogen is 



