J. L. Smith — Examination of American Minerals. 359 



ity of shafting within the limits of ordinary shop practice, a 

 reduction of the coefficient of friction of quite .titty per cent 

 may be made. The pressure on the shaft might also be reduced, 

 for it would be unnecessary to maintain so great a tension upon 

 the belts, and thus in some cases a very considerable economy 

 of power might be effected. We know that in many shops a 

 large fraction of the power developed by the engine is expended 

 in overcoming the friction of the shafting and machinery. 



On the other hand, it is desirable that the friction of the belt 

 upon the pulley should be as great as possible. The conditions 

 usually met with, which determine the friction of belts, are, 

 low intensities of pressure, a rubbing surface which yields with 

 considerable ease. In such cases a high speed is needed to 

 develop the greatest amount of friction. See Tables III and 



experimental v Ration. 



I hope soon to be able to give tabulated results, 

 have a certain practical value to working engineers. 



Art. XLL— Examination of American Minerals. No. 6.— 

 Description of Cohunhir Arid M->^rohjr»m „>><■ 

 the Unitea 



the name C»lnm/.i»»i to the element now call"' 1 ! 



Description and anal)/ r ( >••••-. v ' ■ ' - '' • /■'' " >'>>'■ 



and Venj. > >> - UaH: W 'it , and Rogers ite ; 



by J. Lawrence Smith, Louisville, Ky. 



It is the common practice < -*~ nn( ^ m ^ n " 



eralogists to speak of the metal which is called X<ol ><m by 

 English and continental chemi-t-. as ( ambi> < This is emi- 

 nently just, since the 11 eti was disc v, red 

 named columbium. h ' the name Dlob "Jf 



«- given to it. Tl e change of nm ie was caused by a double 



still n no wa\ . »\-ted ith t filial bservatiuns in 



1801 bv Prof. Hatchett of England. 



These mistakes arose as follows:— In the first place, Eke- 

 bergdisem. . : he called 



' ' ' • 

 and columbium were synonymous terms in all works on chem- 

 istry, tli ' r: H?! " 

 ondlj, when II. Eose made his well-known ex 

 researches on the columbite of Bodenmais, he showed that this 



Am. Joub. 8ci.-Third Sebie8, Vol. XHI, No. ?7.-Mat, 1877. 



