20 SOME PRINCIPLES AND METHODS OE ROCK ANALYSIS, [bull. 176. 
shown that with the pioneer in this line at least the guaranty amounts 
to nothing, the reagents being sometimes worse than the U C. P." 
articles emanating from sources which make no claim to special purity 
for their goods, and redress being unobtainable. The "guaranteed 
reagent" needs checking as much as any other. 
VIII. PRELIMINARY QUALITATIVE ANALYSIS. 
A complete qualitative analysis of a rock, preceding the quantitative 
examination, is in most cases a sheer waste of time. A few constitu- 
ents may now and then be specially looked for, but in general time is 
saved by assuming the presence of most of them and proceeding on 
that assumption in the quantitative analysis. 
