Organic Acids in the Examination of Minerals. 21 



BEHAVIOR OF CERTAIN SILICATES WITH HCL AND WITH CITRIC ACID. 



Mineral. 



Wollastonite 

 Chrysolite . . 



Olivine 



Willemite . . . 

 Wernerite . . . 

 Chondrodite 



Datolite 



Pectolite 



Chrysocolla . 

 Calamine ... 



Prehnite 



Apophyllite . 



HC1 



c 



1G 



IS 



1G 



2 



1G 



3 



1G 



1G 



1-2 



3 



1G 



1-2 G 



1G 



1G 



1G 



1G 



1 



1 



1G 



1G 



1 



2 



IS 



2S 



Mineral. 



Khodonite 

 Natrolite . 

 Analcite . . 

 Chabazite 

 Stilbite . . . 

 Serpentine 

 Retinalite 

 Chrysotile 

 Deweylite 



Talc 



Epidote .. 

 Orthoclase 



HC1 



1 

 1G 



IS 



IS 



1 



IS 



IS 



IS 



IS 



3 



3 



3 



C 



1 



1G 



IS 



IS 



IS 



IS 



2-3 



IS 



3 



3 



3 



In order to ascertain approximately the comparative de- 

 composing power of the commoner organic acids with silicates, 

 two which yield readily to citric acid and one which is 

 attacked with difficulty were selected for treatment. The fol- 

 lowing are the results : 



Calamine. Natrolite. 



Citric Acid 

 Tartaric " 

 Oxalic " 

 Formic " 

 Malic " 

 Acetic " 



... 1G ... 



.... 1G ... 



... 2 



... 1G* ... 



... 1G ... 



... 1G ... 

 * Very soluble. 



1G 



1G 



3 



1 



1G 



2-3 



Prehnite. 



.... 2 



.... 3 



.... 3 



.... 3 



.... 3 



.... 3 



Since calamine and willemite are sometimes distinguished 

 by their behavior with acetic acid — the former gelatinizing and 

 the latter giving slimy silica — it was thought of interest to 

 examine their behavior with other organic acids. The results 

 are given below : 



Calamine. 

 1G ... 



Citric Acid 

 Tartaric " 

 Oxalic " 

 Formic " 

 Malic " 

 Acetic " 



1G 



2 



1G 



1G 



1G 



Willemite. 

 .. 1G 

 .. 1* 

 .. 2 

 .. IS 

 .. 1 

 ..IS 



* Solution becomes yery milky in appearance. 



