THE PROPERTIES OF MINERALS. 



Tahle of Atomic ]\'ei(ihU — ("oiitiinicd. 



651 



Xaine. 



Neodyniinm .. 



Nicki-l 



Nitrogen 



Osmium 



Oxygen 



Palladium 



I'liosidiorus... 



Platinum 



Piitassium 



Praseodymium 



Kliodium 



Rubidium 



Ruthenium . .. 



Scandium 



Selenium 



Silicon 



Silver 



Symbol.: weight. 



Kdi... 140.5 



Ni . . - . 58. 69 



N 14.04 



Os 190. 99 



O 16.00 



Pd.... 100.36 



P 31.02 



Pt . . . . 194. 89 



K 39.11 



Prd...[ 143.5 



Rh . . . I 103. 01 



Rb....: 85.43 



Ru.... 101.68 



So 44.0 



Se.... 79.0 



Si .... 28.40 



Ag . . - 107. 92 



Name. 



Symbol, 



Sodium ' Na. 



Strontium Sr . 



Sulphur S - . 



Tantalum Ta . 



Tellurium Te . 



Terbium Tb. 



Thallium Tl . 



Thorium Th. 



Tin Sn . 



Titanium — Ti . 



Tungsten W. 



Uranium U . . 



Vanadium i V . . 



Atomic 

 weight. 



Ytterbium 

 Yttrium . . 



Zinc 



Zirconium 



Yt. 

 Y.. 

 Zn. 

 Zr. 



23.05 



87.01 



32.07 



182. 6 



127.0 



160.0 



204.15 



232. 63 



119. 05 



48.15 



184.84 



239. 59 



51.38 



173.0 



88.95 



65.41 



90.6 



Berzelins, in bis electro-chemical hypothesis, distinguished certain 

 relations between the different elements by the terms electro-negative 

 and electro-positive. Later, the terms acidic and basic came into use. 

 As synonymous with these, the terms negative and positive are now 

 used, although they, like the others, are not free from objections. 



From the combinations of the elements, the more negative uniting 

 with the more positive in varying proportions and in groups of two, 

 three, or more, all known compounds are produced. These unions take 

 place in accordance with certain general chemical laws, the observation 

 of which has given rise to the hj^pothesis that the elementary bodies 

 are made up of indivisible particles, called atoms, and that chemical 

 combination takes place through the union of these atoms. A group 

 of atoms thus united is called a molecule. 



All minerals are composed of either an element alone or two or more 

 elements in combination. Elements are said to combine when, on 

 bringing them together, a new substance is produced, diftering from 

 and possessing properties which, as a rule, are not the mean of those 

 of its constituents. For example, the gases hydrogen and oxygen 

 under the proper conditions combine to form water, a liquid. These 

 combinations are represented symbolically by the juxtaposition of the 

 symbols of the component elements. Thus, a molecule of water, com- 

 posed of two atoms of hydrogen and one of oxygen, is rei^resented by 

 the symbol YliO. The multiplication of a group of atoms is denoted by 

 placing the proper numeral to the left of a group of symbols, or by 

 inclosing them in parentheses and placing a small numeral to the right. 

 Thus, 3H2O or (HaO)^ denotes three molecules of water. The combina- 

 tion of groups is expressed by placing their symbols in juxtaposition 

 with a i)eriod between them. Thus, Fe>03.El20 denotes a compound of 



