342 Screntific Intelligence. 
SCIMNTIFIC. INTELLIGENCE: 
I. CHEMISTRY AND PHYSICS. 
1. Conversion of the black to the red mercuric sulphide.—In a 
series of careful experiments W. Sprine has obtained the follow- 
ing values for the specific gravity and specific volume of the 
black mercuric sulphide precipitated, and for the red sulphide 
both precipitated and sublimed. 
Black, precipitated. 
18°-3 23°6 35-2 56:5 77-5 
SPs PTAvnn ayy, 6242 7°6047 7'5686 7°5500 75578 
Spavol...-2 131°160 131°496 132°124 132°452 132°313 
Red, precipitated. 
21°°6 23°5 34°6 56°5 177 
Sp. grav.--- 8°1289 8°1246 8°1016 8°0851 8°0871 
wp: voll.eu. 123°018 123°082 123°432 123°684 123°653 
Red, sublimed. 
15°°8 18-0 34:6 56°6 115 
Sp. grav.- -- 8'°1587 8°1464 8°1199 80906 80979 
Sp. vol. 2.8 122°569 122°754 123°154 123°600 123°488 
The above values, treated graphically, prove that the volume 
varies with the temperature with both the sulphides. The expan- 
sion increases rapidly with the temperature then grows less and 
less, finally diminishing so as to give a maximum at about 56°. It 
is hence concluded that the cause of the difference in color is to 
be found in the constitution of the molecule and not in their 
orientation, that is in the crystallization. On comparing the 
specific gravity with the molecular weight (232), calculation 
shows further that the molecule of cinnabar must contain the ~ 
group HgS fifteen times if the black sulphide contains it fourteen 
times. The following are determinations of the specific heat at 
different temperatures of the two sulphides, both precipitated : 
Black, Red. Ratio. 
Dae ROY SL) nae ee 0:08348 0°07487 1°115 
35° to 40°____._ 0°09668 0°08707 sh TLD) 
ASP oe, BON. ih 0'11015 0°09335 1:118 
Be rereO eda +. < 0:11034 0°09852 1°120 
655 HOMO mececs 0°12065 0°10737 1°123 
75s tORew if oo. 0°14328 0°12702 1:128 
The above values of the specific heat correspond at different 
temperatures to those of the volumes as given above. On com- 
paring the volumes of the black and red sulphides at the same 
temperature the values 0°888 and 0°932 are obtained. From these 
