336 Review of Algeria Phillips^ Mineralogy, 



cency in the present state of science. We observe farther, that 

 anthophyllite, shown of late to have the same general formula 

 with hornblende, is separated from it by fifteen or twenty species 

 of very various characters ; and many more, separate bronzite, hy- 

 persthene, acmite and Cummingtonite, from augite. Automolite 

 and dysluite, having the same general formula with spinel, are 

 yet twenty pages oif. Bat farther illustration is unnecessary. 

 Whatever may be said of chemical systems of classification, 

 surely this has little to recommend it, failing as it does of all the 

 advantages of system, and not even securing the benefits of an al- 

 phabetical arrangement. The remaining classes are less objec- 

 tionable. The class of metals and metallic ores might have been 

 conveniently subdivided into orders, including each the ores of a 

 metal, instead of forming, as now, an unbroken series. The or- 

 der in which the metals succeed one another is quite at variance 

 with the teachings of chemistry. 



We are confident that Mr. Alger has not done justice to his 

 own science in the classification adopted ; and certainly not to 

 Mr. PhilUps, in presenting the views of twenty years since under 

 his name in 1844. 



The table of formulas for the composition of minerals added to 

 the volume by Mr. Alger, are given mostly in mineralogical sym- 

 bols. Concerning these formulas, we read in the Preface : "Chem- 

 ical formulas have occasionally been given when employed by the 

 analysts themselves, or in stating the composition of some of the 

 more complex species, particularly of the metals ; but for the pur- 

 poses of mineralogy, they should not be generally introduced to 

 the exclusion of the mineralogical signs, which answer all the 

 ends desired in making known the proximate constituents of the 

 species, and do not involve a knowledge of chemistry beyond that 

 which most students should possess." Justice is hardly done to 

 the mineralogical symbols, in implying that they make known only 

 the proximate constituents of the species : for the information con- 

 veyed relative to the composition is as definitely stated as by 

 chemical symbols ; and a better knowledge of chemistry appears to 

 us necessary to understand the former than the latter. The 

 mineralogical formula for Boltonite (Alger, p. cxxx,) MgS-, 

 conveys as definite an idea of its constitution to the chemist, 



as the corresponding chemical formula, Mg^'Si^. The index 

 (^) after S, implies that the atoms of oxygen in the silica are 



