OF ARKANSAS. 169 
Protoxide of manganese -------- 19.08 eet Paes 
Baryta ee 2.75 ‘“ “ 4.84 1 
Oxide of cobalt ss+ee ese ee eeeee 0.15 ee ws 
Wale? <6ciaws pwinreae ves var we’ 16.33 « 14.52 3 
100.72 
This is the same formula which Rammelsberg established for the com- 
position of the wad from Rubeland (v. 2d supplement, p. 167). 
Proceeding in the same manner with the analysis of No. 22, that is, 
rejecting silicic acid and peroxide of iron, and calculating the remainder 
for 100, we have: 
Protoxide of manganese+++++++eeeee sevens 86.96 
OXYZEN cere ee eee eee cece eee ence nes 9.20 
Eslimieis 62d ict Seah ee FAS Pe eee A aes SR le 212 
Magnesia errcer cee e ere ee ener ee ee even ens 0.22 
WE BGG Teta aes wish.cer ge a saivas Bi cwie ge See Ne wl Sere Ge ESOL Rar tise 1.50 
100.00 
86.96 parts of protoxide of manganese consist of 67.41 of manganese and 
19.55 of oxygen; hence we have, in toto 67.41 manganese to 28.75 oxygen, 
corresponding to the ratio 69.68 Mn: 29.72 0; 
the compound MnO? requires 69.68 Mn: 30.42 O, 
so that the mineral may be considered as sesquioxide of manganese, or 
braunite, under the supposition that we are justified in rejecting lime, 
magnesia, and water as adventitious. Butif these bases have to be taken 
into consideration, and the free oxygen is united with a portion of the 
protoxide of manganese to the formation of peroxide, we have: 
Peroxide of manganese--+++++ 50.10 contains O 18.40 
Protoxide of manganese--+-+> 46.06 fs “ 10.36) 
LIMe «cece cence ene ever eee nae 9.12 6 “« @9.60 ! 
MAcnESIy «xy seansaseeaiuas 022 « « gog fl?87 
Water cvceere eevee recne 1.50 “ce “ 1.33 ) 
Here the oxygen-ratio of RO : MnO? is nearly as 4 : 6, which would lead 
to the formula 
4 (MnO. CaO. MgO. HO). 3 MnO? 
Jam not at present prepared to pronounce in favor of any of these 
views, but asI am continuing” my investigations into the composition of 
the massive manganese-minerals, I hope to find myself soon enabled to 
advance some well-founded views on the subject. ‘ 
