@, H. Seyms—Relation of Franklinite to the Spinel Group, 211 
I I Mean 
SiO, “17 17 17 
Fe,0, 63°42 63°38 63°40 
Mn,0O, 4°44 4°44 444 
nO 10°39 10°53 10°46 
ZnO 23°11 2312 23°11 
101°53 10164 101°58 
The relation of the metals to the oxygen, taking the mean of 
the two analyses, is given in the subjoined statement. 
Metals. Oxygen. 
Fe, 44°38 19°02) oo. 
Mn, 3-09 1°35 clas 
Mn 8°10 $30} 24 0 
18°55 4°56 
Zn 
Dividing the amount of each element by its atomic. weight 
gives as the ratio of the metals to the oxygen, R: 0 :: 3:3°999 
=R,0, nearly, or an oxygen ratio of the protoxides to the 
Sesquioxides of 1: ‘981 or nearly 1:1, which corresponds to the 
formula of the Spinel group, (R,0, +RO=R,0,). 
he state of oxidation of the manganese here given was 
determined by solution of the mineral in HCl, and estimation 
of the clorine liberated, according to Bunsen’s iodine method. 
L IL. ll. IV. Mean. 
"08 one 08 08 
ALLO; 65 65 eas ei 65 
mice 67°43 67°50 67°32 67°42 67°42 
F 15°68 15°62 ct saliaiaee 15°65 
ZnO 6°79 6°81 6°76 6°75 6°78 
MnO 9-71 9°47 9°51 9°44 9°53 
100°31 100°16 99°97 99°99 100°12 
This gives from the mean of the four analyses: 
Metals. Oxygen. 
Al 35 “30 a 
Fe, 47°19 20-23 ¢ 20°58 
Fe 49-17 3°48 
Zn 5°44 134} 6°97 
Mn 7°38 2°15 
