THE ELEMENTS. 



309 



METALS (continued). 



Symbols 



Atomic or 

 Combining 

 Weights. 



Derivation. 



200 . Heathen deity (quick). 



. 96 . Gr. Molybdena, lead ore, like lead 



58 . Ger. Kupfer nikel, false copper. 

 94 . Columbite. 



199 . Osme, an odour. 



1 06 . Pallas, Minerva. 



197 . Spanish, platina, little silver. 



39 . Potash. 



104 . Gr. Roda, rose. 



85 . Lat. Rubidus, red. 



104 . (Not known.) 



1 08 . Hebrew, money. 



23 . Salsoda plant. 



87 . Strontian, N.B. 



182 . Tantalite mineral 



. (Not known.) 



204 . Gr. Thallos, green twig. 



230 . Thor, deity. 



. ItS . (Not known.) 



50 . Titans. 



184 . Swedish. 



240 . Urania. 



51 . Vanadis, a goddess in Sweden, etc. 



- 93 ( Not known.) 



6$ . Ger. Zinken, nails. 



89 . Ger. Zircon, four-cornered (Ceylon). 



The term " combining weight " requires a little explanation. We are 

 aware that water, for instance, is made up of oxygen and hydrogen in 

 certain proportions. This we will prove by-and-by. The proportions are 

 in eighteen grains or parts of water, sixteen parts (by weight) of oxygen, 

 and two parts (by weight) of hydrogen. These are the weights or propor- 

 tions in which oxygen and hydrogen combine to form water, and such 

 weights are always the same in these proportions. Chemical combination 

 always occurs for certain substances in certain proportions which never vary 

 in those compounds, and if we wish to extract oxygen from an oxide we 

 must take the aggregate amount of the combining weights of the oxide, and 

 we shall find the proportion of oxygen ; for the compound always weighs 

 the same as the sum of the elements that compose it. To return to the 

 illustration of water. The molecule of water is made up of one atom of 

 oxygen and two atoms of hydrogen. One atom of the former weighs six- 

 teen times the atom of the latter. The weights given in the foregoing 

 table are atomic weights, and the law of their proportions is called the 

 Atomic Theory. 



An atom in chemistry is usually considered the smallest quantity of 

 matter that exists, and is indivisible. A molecule is supposed to contain 

 two or more atoms, and is the smallest portion of a compound body. The 



