wells: interpretation of mineral analyses 



421 



which is obviously theoretically correct for each formula assumed.^ 

 It is then only necessary to multiply the combining ratios found, 

 bj^ this factor, to obtain the exact atom numbers found in the 

 analysis. 



The comparison of the analysis under discussion with theory 

 may therefore be made by either of the two following methods: 



(0 2748\ 

 „ ' „ j X 107.88. Simi- 

 larly for the copper. In the case of replacements such as that of copper for silver 

 here the molecular weight assumed must be obtained by taking proper propor- 

 tions of the atom numbers of the simplified formula. As the number of replace- 

 ments increases, the more difficult it becomes to derive either a "theoretical" 

 molecular weight or a theoretical percentage. 



- Obtained from 17.48, etc., above by dividing by -atomic weights. 

 ' Considered as Ag2 and Cua. 



/2009 1^ 

 * Obtained from 0.5451, etc., by multiplying by ( 



molecular weight assumed. 



where 2009.1 is the 



M 

 ^ If M is the molecular weight assumed 1 per cent of M is — ; if y per cent of 



IT 



an element has been found, the molecular portion will be — and this will be as 

 many atoms as the atomic weight of that element is contained in ^— - or -^ — ; 



hence the factor for each molecular ratio will be 



100' 



