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may contain only thofc ingredients which their compound names 

 import. But raineials whofe principal compoiition is analogous,, 

 often contain other fubftances alfo, which the new chymical name 

 'would not expref?, and would thus lead to important miftakes. 

 Thus, for inftance, pbofphorite is commonly contaminated with 

 filex, aerated lime, muriated lime and iron, and fometimes 

 with manganefe and fluor ; whereas the analogous chymical 

 compound on which the name phofphorated lime is properly 

 impofed, is free from fuch contaminations. Subftances therefore 

 fo different fhould certainly be diftinguifhed by different names, 

 or at leaft the word natutal ox native muft be tacked to the name 

 of the chymical compound ; and though with refpedi to foillle 

 metallic chymical compounds this inconvenience may often be 

 avoided by the addition of the word ore ; yet here alfo the antient 

 name often expreffes, fome other inherent property, thus the term 

 vitreous added to filver ore denotes not only the conapofition but 

 alfo the eafy fufibility of that particular ore. 



Another inconvenience arifing from denominations aTming to 

 exprefs the composition of the objects on which they are beftowed, 

 is, that they often cannot exprefs the proportion of the compound- 

 ing ingredients without confiderable embarraffment ; this propor- 

 tion neverthelefs is a circumftance often of great importance, as 

 it induces an important difference in their properties, and the e^n- 

 barraffment is greater when the compounding ingredients are 



numerous. 



