I go STUDIES FOR STUDENTS 



statement that he found Widmanstatten figures on a mass obtained 

 by reducing iron and nickel chlorides from their vapors. J. 

 Lawrence Smith states that he obtained Widmanstatten figures 

 on a button of iron which cupelled from a mixture of iron sili- 

 cate and chalk heated to fusion for from 15 to 20 minutes in 

 oxygen in excess. If the excess of oxygen was essential to the 

 success of this experiment, it was a condition certainly wanting 

 in the formation of the iron meteorites. 



It is true of chondri as of Widmanstatten figures that they 

 have not yet been successfully reproduced by synthetic methods. 

 Especially has it been found impossible to reproduce the struc- 

 ture exhibited bv many enstatite chondri, of fibers radiating from 

 a point eccentrically placed with reference to the center. 

 Meunier has obtained from vapors of silicon chloride and mag- 

 nesium acicular crystals of pyroxene which he recently showed 

 the writer, which radiate in a fashion recalling the above-men- 

 tioned chondri. They cannot, however, be said to be in any 

 sense reproductions of the chondri, and they are moreover a 

 monoclinic pyroxene. Perhaps the nearest approach in form to 

 these structures has been obtained recently by Brauns in crys- 

 tals obtained by cooling sulphur. The forms were produced 

 either by suddenly cooling a strongly heated preparation of sul- 

 phur or by slowly cooling and suddenly shaking it. Such results 

 suggest that the peculiar structures of chondri indicate special 

 conditions of cooling or percussion to which the mass has been 

 subjected. If these conditions could be reproduced, chondri 

 could, perhaps, be formed synthetically. It may be suggested 

 that immediate contact with the intense cold of space, a condi- 

 tion which has not yet been experimentally fulfilled, is perhaps 

 the force which has given chondri their peculiar form. 



Note. — For further study and for lists of references the following works 

 may be consulted: Meteoritenkunde, Heft I, E. Cohen, Encyclopedic 

 chimique, Tome II, Meteorites, S. Meunier ; Die mikroskopische Beschaf- 

 fenheit der meteoriten, G. Tschermak. 



O. C. Farrington. 



Field Columbian Museum, 

 Chicago. 



