222 Reviews — Copper Sulphides. 



with the large mass of Whitfield County iron. Examination of thin 

 sections, however, revealed marked differences. The Hidden iron is 

 marked bv broad areas of plessite and a peculiar swelling of the 

 kamacite bands, while between the two alloys are the regularly 

 disposed, parallel lying tsenite bands. In the, Shepard iron the 

 kamacite bands are not swollen, but show very straight borders, and 

 the tsenite bands are thinner, while it contains small, irregularly 

 scattered, granular, and dendritic particles of schreibersite. The 

 analyses gave similar figures, but that is not unusual in meteorites of 

 this class. The author proposes the names Whitfield County and 

 Dalton for the Hidden and Shepard irons respectively. The Cleveland 

 iron also must belong to a distinct fall. 



V. — On certain possible Distributions of Meteoric Bodies in 

 the Solar System. 1 By Harold Jeffreys. 



IN the third part of this paper the author deals with problems of 

 fundamental importance to geologists, since it bears directly on 

 the question of the initial condition of the earth, whether gaseous, 

 molten, or solid. The following quotation from the introductory 

 paragraph expresses the conclusions to which Mr. Jeffreys has" arrived: 

 "The objections to the Nebular Hypothesis are first summarized, and 

 it is then shown that while the Planetesimal Hypothesis avoids most 

 of them, it is nevertheless open to a new one, namely, that collisions 

 between the small bodies would be so frequent, and would occur with 

 so high a velocity, that the particles would be fused and volatilized 

 long before accretion could produce any important effect on bodies as 

 large as the planets. If the planetesimals be supposed to have moved 

 initially in nearly circular orbits, this objection is avoided, but the 

 planets are required to have always been very large." 



YI. — Some Reactions involved in Secondary Copper Sulphide 

 Enrichment. By E. G. Lies, E. T. Allen, and H. E. Merwin. 

 Economic Geology, vol. xi, pp. 407-503, 1916. 



TI1HE reactions of a number of natural sulphides, viz. chalcocite 

 (Cu 2 S), covellite (Cu S), Bornite (Cu 5 Fe S 4 ), chalcopyrite 

 (CuFe Sa), pyrrhotite, pyrite (Fe S 2 ), sphalerite (ZnS), and galena 

 (Pb S), with copper sulphate solutions in all cases, gave rise to 

 a copper enrichment product, and in all cases the sulphate of the 

 metal contained in the original sulphide was formed and usually 

 sulphuric acid as well. Cupric sulphate acts as oxidizing agent, not 

 only at elevated but also at lower temperatures. The sulphide 

 enrichment products are crystalline and adhere firmly to the altered 

 sulphide as in nature. The order of stability of these products 

 towards cupric sulphate is : chalcopyrite, covellite, chalcocite. Bise 

 of temperature affects the rate rather than the nature of the reaction, 

 but at high temperatures hydrolysis plays a part. 



1 Monthly Notices of R.A.S., December, 1916, p. 84. 



