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other, the amount of such combinations would be infinite, 

 and the number of minerals endless ; but their combinations 

 are limited by two important laws ; the first of which is, 

 that certain substances have so strong an affinity for each 

 other as to combine and prevent combination between others 

 whose affinities are more feeble ; while in all bodies which 

 are chemical combinations, and not mere mechanical mixtures, 

 the ingredients unite only in definite and invariable propor- 

 tions. Thus hydrogen unites only with eight times its weight 

 of oxygen to form water ; while this is the lowest proportion 

 in which oxygen enters into combination. The following 

 explanation of chemical nomenclature, extracted from the 

 excellent work of Dr. Turner, will convey, not only an expla- 

 nation of mere terms, but with these, of the most important 

 principles of chemistry as connected with mineralogy. 



"Chemistry," he observes, "is indebted for its nomen- 

 clature to the labours of four celebrated chemists Lavoisier, 

 Berthollet, Gruyton Morveau, and Fourcr-oy. The principles 

 which guided them in its construction, are extremely simple 

 and ingenious. The known elementary substances, and the 

 more familiar compound ones, were allowed to retain the 

 appellations which custom had assigned them. The newly 

 discovered elements were named after some striking pro- 

 perty. Thus, as it was supposed that acidity was always 

 owing to the presence of the "vital air," discovered by 

 Priestley and Scheele, they gave it the name of oxygen, 

 derived from two Greek words, signifying a generator of 

 acid ; and they called " inflammable air " hydrogen, from the 

 circumstance of its entering into the composition of water. 



" Compounds, of which oxygen forms a part, were called 

 acids and oxides, according as they do or do not possess 

 acidity. An oxide of iron or copper, signifies a combination 

 of these metals with oxygen, which has no acid properties. 

 The name of the acid was derived from the substance acidified 

 by the oxygen, to which was added the termination ic. Thus, 

 sulphur^ and carbomc acids signify acid compounds 01 

 sulphur and carbon with oxygen gas. If sulphur, or any 

 other body, should form two acids, that which contains the 

 least quantity of oxygen is made to terminate in ous, as 

 sulphurous acid. The termination in uret was intended to 

 denote combinations of the simple non-metallic substances, 



