262 Hillebrand and SchaUer — Mercury 



It had been the intention of the senior author to assign to 

 the mineral a name indicative in some manner of its composi- 

 tion when this should have been fully established, but to now 

 substitute for the name kleinite, already in the literature even 

 though applied to an incorrectly identified species, another 

 name, no matter how appropriate, would occasion confusion 

 that it is desirable to avoid ; hence the name kleinite is 

 accepted without reserve. 



Physical properties. — Most of the material as received was 

 in loose crystals or crystal aggregates, to which adhered more 

 or less of a dull earthy white to reddish foreign matter of a 

 clay-like character. While many of the crystals were very fine 

 and brilliant, much of he material was far too impure for the 

 chemical tests that were contemplated. Even the selected 

 crystals and aggregates held here and there a little of the 

 gangue firmly attached and some must also be included in the 

 crystals themselves in an extraordinarily fine state of division, 

 to judge both from microscopic evidence and from the amount 

 of non-volatile matter that was left on ignition, which ranged 

 from about 0*75 to nearly 3 per cent. This gangue interfered 

 much with the correct determination of the water given off by 

 the mercury mineral on heating and hence with the establish- 

 ment of a formula. 



A peculiarity not noticed by other observers is that when 

 exposed to sunlight or even to the diffused light of a room, 

 after having been in the dark, the crystals, at first canary-yel- 

 low, almost immediately became much deeper in color, 

 generally reddish yellow or orange, but that they regained 

 their original color very soon when again placed, in the dark. 

 This phenomenon could be reproduced as often as desired. It 

 was also noticed that the exposed crystals were not all of the 

 same shade of yellow ; there were some that had not changed 

 at all and others that showed all gradations between almost 

 colorless and orange, and one crystal was seen with an orange 

 core and a light outer zone. Professor Sachs also noticed dif- 

 ferent shades in the same crystal. In powder the color is 

 sulphur-yellow. One of the first specimens received was com- 

 posed entirely of very pale yellow, coherent crystal masses 

 held together by or holding together a reddish earthy gangue. 

 The lighter crystals that were picked out for separate analysis 

 from samples of the loose crystals varied in color, but all were 

 much lighter than the rest in daylight. 



The density was determined on several specimens and found 

 to average for the orange crystals 7*975 and for the light yel- 

 low 7*9S7, but the results are all low because of the attached 

 or included earthy matter. These figures are much higher 

 than the 7*141 given by Sachs. The crystal form is hexagonal ; 



