CONTRACTION IN NATURAL SULPHIDES, 
TABLE SHOWING RATIO OF MOLECULAR CONTRACTION 
SULPHIDES AND RELATED BODIES OF COMMON OCCURRENCE. 
IN 
CERTAIN NATURAL 







ë 3 à Presht Excess of | 
MINERAL. COMPOSITION. nee olen € RS en 
System. | Density. 3 à umes of ener | 
Tron Pyrites........ S 53:3, Fe 46°7 Reg. 5.06 3°06 2 124-64 
Marcasite .......... S 53:3, Fe 46:7 Rhom. 4°81 3°06 1} 109-06 
Mispickel........... S 19:6, As 46, Fe 34:4 Rhom. 6°30 455 i 109°06 
Cobaltine........... S 20, As 45, Co 35 Reg. 6°35 4°60 12 109-06 
Pyrrhotine ......... S 39:5, Fe 60:5 Hex. 4:63 3°63 1 62°32 
Lollingite ........... As 728, Fe 272 Rhom. | 73(?) | 6:3 1 (2) 62:32 
Bismuthine......... S 18:75, Bi 81:25 Rhom. 66 56 1 62°32 
Nickeline. ...... .... As 56-4, Ni 43°6 Hex. 765 69 # 46°74 
Gnaapar------. 2 8 13°8, Hg 86-2 Hex. 8:05 755 3 31.16 
Galena..----..--"".e S 13:4, Pb 86°6 Reg. 75 7:00 À 3116 
Argentite ........... S 13, Ag 87 Reg. 727 | 6.77 1 31-16 
GOVElNE er S 33:54, Cu 66°46 Hex. 4:63 413 4 31:16 
Copper Glance...... S 20-2, Cu 79:8 Rhom. 580 5:29 3 31:16 
SHDTITE eee S 28:24, Sb 71.76 Rhom. 45 40 4 3116 
Bournonite .....+. { BLE, Bp een es Rhom. | 58 53 i 3116 
Hauerite ........... S 538, Mn 46-2 Reg. 346 | 3:06 2 24-90 
Copper Pyrites...... S 34:9, Cu 34:6, Fe 30°5 Tetrag. 42 3:96 4 15°58 
Breithauptite........ Sh 67:8, Ni 32-2 Hex. 75 7-27 4 1558 
Zine Blende......... S 33:2, Zn 66-8 Reg. 4:04 3°84 3 12.46 
Alabandine......... S 36°78, Mn 63:22 Reg 4:0 38 + 12°46 
Smaltine..... eee As 72, Co 28 Reg. 65 6°37 4(?) 7:79 
Orpiments...-.-"... 3 S 39, As 61 Rhom. 345 3°33 $ 7:79 
IREAÏPAR-.-- ce ee S 29:9, As 70:1 Clino-Rh. | 3:7(?) 3°69 0 0 
Greenockite..... alors S 22:2, Cd 778 Hex. 49 497 0 0 






29 
Many oxidized bodies appear to present far more marked examples of condensation 
than any recorded in the preceding Table of Sulphides. 
does not exceed 2°49 or 2°5, the sp. gr. of Quartz equals 2°6 to 2°7. In Aluminium, again, 
the sp. gr. equals 2°6 ; and in Corundum (with only 52°3 Al) it exceeds 3°9. 
Thus, whilst the sp. gr. of Silicon 
In these and 
other similar cases, therefore, either great contraction is revealed, or the metal or other 
base, when liberated from oxygen, must undergo enormous expansion. 
