312 



SCIENCE 



[N. S. Vol. XXXII. No. 818 



SCIENTIFIC JOURNALS AND ARTICLES 



The July number (volume 11, number 3) 

 of the Transactions of the American Mathe- 

 matical Society contains the following papers : 



Eduard Study: "Die natiirliclien Gleichungen 

 der analytischen Curven im Euklidischen Raunie." 



J. W. Young: "Two-dimensional chains and the 

 associated collineations." 



L. I. Neikiric: "Groups of I'ational transforma- 

 tions in a general field." 



P. F. Smith : " On osculating element-bands as- 

 sociated with loci of surface-elements." 



G. A. Bliss and Max Mason : " Fields of ex- 

 tremals in space." 



G. A. Miller : " Groups generated by two op- 

 erators Su Sa satisfying the equation s^s^- = s^s^'." 



L. P. Eisenhart: "Congruences of the elliptic 

 type." 



The July number (volume 16, number 10) 

 of the Bulletin of the American Mathematical 

 Society contains : " A theorem on the an- 

 alytic extension of power series," by W. B. 

 Ford ; " Extensions of two theorems due to 

 Cauchy," by G. A. Miller ; " Existence the- 

 orems for certain unsymmetric kernels," by 

 Anna J. Pell; Eeview of Baker's Multiply 

 Periodic Functions, by J. I. Hutchinson; Ee- 

 view of Bocher's Higher Algebra (English and 

 German editions), by Arthur Eanum; Eeview 

 of Coolidge's Non-Euclidean Geometry, by 

 Joseph Lipke; Eeview of Wieleitner's Spe- 

 zielle Ebene Kurven, by E. G. Bill; Shorter 

 Notices : Borel-Stackel's Elemente der Mathe- 

 matik, Band II. : Geometric, by C. H. Sisam ; 

 Carus's Foundations of Mathematics, by F. 

 W. Owens; Cox's Mechanics, by W. H. Jack- 

 son; Abraham's Theorie der Elektrizitat, vol- 

 ume 2, Elektromagnetische Theorie der Strahl- 

 ung, second edition, by E. B. Wilson; 

 " Notes " ; " New Publications " ; " Nineteenth 

 Annual List of Papers read before the Society 

 and subsequently published " ; Index of vol- 

 ume. 



SPECIAL ARTICLES 



'the composition of some MINNESOTA ROCKS 

 AND MINERALS 



The writer after spending two summers in 

 the field for the Geological and Natural His- 

 tory Survey of Minnesota, has been analyzing 



and gathering data regarding the composition 

 of typical materials, and some interesting 

 variations. The detail of field observations, 

 the petrographic descriptions and the less im- 

 portant types are reserved for future possible 

 bulletins of the survey, but three lines of in- 

 vestigation have given results of general in- 

 terest: (1) analyses of typical acid and basic 

 igneous rocks, (2) mineral analyses, (3) tests 

 for copper in the Keweenawan lavas. 



1. Eock analyses are available from central 

 and eastern Minnesota.' In the central area 

 excellent building and monumental stone ia 

 obtained from two or three types of granite, 

 which occur in laccoliths of considerable size, 

 in Kewatin schists, and are probably them- 

 selves of that age. There are a few masses 

 of gabbro, and the granites are intersected by 

 many diabase dikes and a smaller number of 

 quartz-diabase and quartz-porphyry dikes. In 

 the eastern area are the basic Keweenawan 

 lavas, continuous with the copper-bearing 

 rocks of Michigan. Most of the lavas in 

 Minnesota can be classed in three types of 

 diabase, which show quite distinct field ap- 

 pearance and are mineralogically three points 

 in a series, varying from a mottled rock high 

 in augite to one with conchoidal fracture low 

 in augite, the other constituents showing 

 minor changes. 



The attempt has been made to produce an- 

 alyses of much greater completeness and some- 

 what greater accuracy than those heretofore 

 available, so as to estimate the approximate 

 composition of the fundamental magma exist- 

 ent in this petrographic province. Broadly 

 considered, these two districts are the south- 

 western extreme of a long series of outcrops 

 of igneous material extending northeast to 

 Labrador and northwest to McKenzie. They 

 are thus near the point of a great V. The 

 Wisconsin igneous rocks may be assigned a 

 similar position farther east. South and west, 

 some few igneous materials outcrop on the 

 Minnesota Eiver, but then there is a break to 

 the Ozark Mountains and the Black Hilla. 

 Northward the outcrops are much more abun- 

 dant. 



^Previous work is mostly referred to in the 

 state survey reports. 



