[JOHNSTON-CONNOR] THE BLITHFIELD METEORITE 189 



meteorite according to the methods devised by E. von Federoff, 

 with the exception of the refractive indices which were determined 

 on crushed fragments in oils. 



The thin sections taken for observation were selected with the 

 greatest care and the figures here recorded taken individually are 

 the average of not less than ten measurements upon plates showing 

 clearly the emergence of the optic normals. 

 The mineral is optically positive. 



X\\a,Y\\h, Z\\c. 

 2VNa generally 58° but occasionally showing variations of as much 

 as +4° 



a =1.657±0.005 

 )S =1.660 ±0.005 

 7 =1.667±0.005 



Birefringence {^ — a) measured =0.003 

 Cleavages m ( 110), a(lOO), mAw = 88°30' 

 Parting t?(410). 



Chemical Analysis and Examination of the Blithiield Meteorite 



By M. F. Connor 



The sample taken for analysis was a 20-gramme fragment broken 

 from the interior of the meteorite and apart from a slight brownish 

 tinge which is common to the mass throughout it showed nothing 

 which might be taken as evidence of deterioration. 



The fragment was first crushed on a heavy steel plate by gentle 

 tapping with a heavy steel pestle protected by a polished iron cylinder 

 to avoid loss by scattering. The coarse powder thus obtained was 

 subjected to the influence of an electromagnet, and the magnetic 

 portion subjected to further crushing and treatment with a magnetic 

 comb, similar to that devised by E. G. Prior of the British Museum, 

 in order to free as far as possible the nickel iron constituents from 

 non-magnetic materials. This treatment was repeated with the 

 greatest care until inspection with the microscope revealed no foreign 

 matter adhering to the metal. This latter was found to weigh 2 6 

 grammes and was in the form of minute particles and grains of from 

 I to 2 millimetres in diameter. 



It yielded on analysis — 



Iron 91.62 



Nickel 6.69 



Cobalt 0.45 



Copper . 0.08 



Manganese 0.01 



