52 Reéxamination of American Minerals. 
i, 
umina, . 64:24 . e 63°48 
Peroxyd iro: trace 4 A trace 
SS ; 33°76 ; 84°68 
ca, 5 ‘ 1:33 : 1:09 
Phosphoric acid, . A 57 ; i é trace 
Magnesia, , ; ‘10 ; 05 
100-00 99°30 
The phosphoric acid was determined by molybdate of am- 
monia ; the small amount of silica is due to the intimate mixture 
of the mineral with allophane. From the results of these examin- 
ations, we are confident that Mr, Hermann has not at any time 
analyzed pure Gibbsite. 
26. Emerald Nickel. 
We notice in the last edition of Phillip’s Mineralogy, that Prof. 
Miller and Brooke place this species among the doubtful ones, 
without however giving any reasons for so doing. ‘To ascertain 
if any good reason existed for this doubt, we have reanalyzed it, 
and find the same composition as given by Prof. Silliman, Jr.;* 
which was, 
Oxyd Nickel. Carbonic Acid, Water. 
f 58: 11°69 29°49 
We obtained, 
Oxygen 
Oxyd of nickel, ; ‘i 56°82 12°10 
Magnesia, ‘ ; “67 
Carbonie acid, ri : 11°63 i ; 8:46 
Water, ; ‘ 29°37 ‘ 26°56 
which gives the formula, Nit +671. . 
Atoms, At weight. Per cent. ratio. 
Oxyd nickel, ~. eciae. 1408" 59°72 nee 
Carbonie acid, 1 275 11-66 2 
Water, 675 28°62 6 
6 
We would prefer expressing i 
ate of Nickel plus two atoms of the hydrated oxyd of nickel ; this 
to form a carbonate of the totoxyd of nickel, by precipitating 4 
protosalt with an alkaline carbonate, a carbonate is obtained, 
* This Journal, [2] vi, 248. 
