Royal Astronomical Society. 145 



It seems, therefore, extremely probable, that the cause of the near 

 approach to blackness in the fracture and filings of this alloy, arises 

 from the excessive minuteness of its particles, and thus fulfils the 

 foregoing prediction ; the brownish tinge being produced by the 

 reflexion of a little red light *. 



The polish and power of reflecting light of the anomalous alloy 

 are not quite so great as those of the normal, but are still remarkable ; 

 and, as it seemed a matter of some interest to determine whether 

 both reflected the same quantity or intensity of light at equal angles, 

 the author endeavoured to ascertain this point as respects heat, by 

 means of Melloni's pile for the galvanometrical determination of 

 temperature, assuming, as suggested to him by Professor MacCul- 

 lagh, that what would be true of heat in this respect, would also be 

 so of light ; but from the small size of the reflecting surfaces he had 

 at his command, he found it impossible to arrive at any trustworthy 

 result. He is, however, inclined to believe, that both metals reflect 

 most at a perpendicular incidence. 



From the foregoing detail of the properties, in several respects so 

 different, of this substance in its normal and anomalous states, the 

 author thinks he is warranted in pronouncing it the first observed 

 instance of an approach to dimorphism in a metallic alloy ; and one, 

 the mode of production and characteristics of which present several 

 points of interest. 



The conditions under which the alloy was aggregated, involved 

 extremely minute division of the metal, great pressure in forcing 

 the divided particles into contact, and nearly the exclusion of air. 

 Considerable electrical disturbance may have also cooperated ; such, 

 together with induced magnetism, being the constant accompani- 

 ments of motion in heavy machinery. By re-establishing these con- 

 ditions, under suitable arrangements, the author hopes to repeat the 

 results thus accidentally first obtained, and so produce possibly di- 

 morphous states of other metals or their definite combinations. 



There is but one body which occurred to the author presenting 

 an analogy to this anomalous alloy, namely, indigo ; whose fracture, 

 it is well known, is fine earthy, and of the usual blue colour, but 

 becomes coppery, or assumes the metallic lustre on being rubbed or 



burnished. 



ROYAL ASTRONOMICAL SOCIETY. 

 [Continued from vol.xxii. p. 570.] 



June 9, 1843f. — The following communications were read: — 



I. On a Self-acting Circular Dividing Engine. By W. Simms, Esq. 



The original graduation of a circle, notwithstanding the great 

 improvements in the method invented by Mr. Trough ton, is still 

 attended with very great difficulties, requiring not only the greatest 



* Since this paper was read, Professor Lloyd suggested to the author, 

 the analogy between the appearance of the powder and filings of the ano- 

 malous alloy and Platina Mohr, and those powders obtained by reduction 

 of other metals by hydrogen. None of these, however, are coherent, which 

 constitutes the peculiarity in the present case. 



T The proceedings of the Society in April and May will be noticed 

 hereafter. 



Phil. Mag. S. 3. Vol. 23. No. 150. Aug. 1843. L 



