70 



CHEMICAL PROPERTIES OF MINERALS. 



The following table contains the reactions of some of the 

 metallic oxyds with the ordinary fluxes :* 





Borax. 



Salt of Phosphorus. 



Soda. 



Titanic acid 



0, colorless or 



0, colorless, trp 



Deep yw, hot ; 





milky 





w or gyh, cold 



Oxyd of iron 



0,red,hot;ywh 



0, red, hot; paler or 







or colorless, 



colorless, cold 







cold 









R, green or bh 







Oxyd of cerium 



0, r ; yw on 



0, fine r, hot ; col- 







cooling ; w 



orless, cold 







enamel on 









flaming 









R, colorless or 









w enamel 







Oxyd of manga- 



0, amethystine 



0. amethystine 



PI. trp gn,hot 



nese 







bh-gn, cold 



Oxyd of cobalt 



0, trp blue 



0, blue 



PI. pale r, hot ; 

 gray, cold 



Oxyd of chrome 



0,bn,hot ; pale 



0, green 



0. PL dull or- 





gn, cold 





ange; op&yw 





R, emerald-gn, 



R, green 



on cooling 





cold 







Oxyd of copper 



0, "green 



0, green 



PI. gu, hot ; col, 





R, colorless, 



R, colorless, hot ; r 



op, cold 





hot ; but sud- 



on solidifying 







denly opaque 









and rdh on 









cooling 







The following are other reactions : 



Nitrate of cobalt in solution added to the assay after heat- 

 ing fo redness, and then again heated, produces before fusion 

 a blue color for alumina and a pale-red for magnesia. 



Boracic acid fused with a phosphate produces a globule, 

 into which if the extremity of a small iron wire be inserted, 

 and the whole heated in the reduction flame, the globule at- 

 tached to the wire will be brittle, as proved by striking it 

 with a hammer on an anvil. Before this trial it should be 

 ascertained that no sulphuric or arsenic acid is present, which 

 also may form a brittle globule with the iron ; nor any 

 metallic oxyd reducible by the iron. 



For what is nitrate of cobalt used ? 

 sjcid used ] 



How and for what is boracic 



* stands for oxydating flame ; R for reducing flame ; Ch for char- 

 coal ; trp for transparent ; bh bluish ; yw yellow ; gn green ; r red ; 

 gyh grayish ; w white ; PI in platinum forceps ; op opaque. 



