C. U. Shepard on Hermannoh'te. 1-il 



of Dr. R Hermann of Moscow, to whom chemistry has been 

 so much indebted for the elucidation of this difficult group of 

 minerals. By reference to my description of the mineral it will 

 be seen that I went no further than to determine the proportions 

 of the bases, and of the metallic acids with which they were 

 united, without attempting to ascertain the order in which the 

 latter were present. I thus found : 



Metallic acids, 78*30 



Protoxide of iron, 13-86 



Protoxide of i 



Desirous of learning the exact proportions of the diflPerent 

 acids, I availed myself of an opportunity during the past sum- 

 mer of sending specimens to Mr. Hermann for this purpose. 

 He has had the goodness to perform the analysis, and to com- 

 municate to me his results in the following letter. 



"Your opinion that the mineral from Haddam, which you 

 most kindly named for me, was not columbite has been fully 

 corroborated : for it contains no hyponiobous acid (Nb^O'), as 

 the columbite does; but niobous acid (NbO''); and, in addition, 

 hypoilmenic acid (I^C), and also, a small quantity of bypo- 

 tantalic acid (Ta^O^- The chemical formala is therefore quite 

 different from that of the Columbite: i. e., notRO, Me^O^, but 

 2(2RO, 3Nb02) + (RO, Me206)I1206 = {iTa20sH-|I120s). 



The result of the analysis ^ 



Hypotantalic acid, 7*029 



o_.^^ 



ous acid, . 56-154 12290 



Protoxide of iron, 12-560 2-79 ) 



Protoxide of manganese, 9-340 2-10 \ 



The lower specific gravity of the mineral observed by you as 

 well as the easy solubility in sulphuric acid of the metallic 

 acid present, are readily explained from their small content of 

 tantalic acid, and from the greater proportion of oxygen in 

 the niobous acid as compared with that of the hyponiobous 

 acid in Columbite." 



