AND DESERVING THE ATTENTION OF IMINEIIALOGISTS. 
39 
5. The red precipitate collected on the 
filter, (in paragraph 4) was well washed, and 
while still moist, dissolved in muriatic acid. 
This solution was mixed with a great excess 
of caustic potash, and boiled for two hours 
in a porcelain vessel ; the whole w'as then 
passed through a filter. The liquid which 
passed through was colourless ; the matter 
remaining on the filter was dark red. 
6. The potash solution which thus passed 
through the filter, together with the washings 
of the filter, wasevaporated to dryness in ra- 
ther a strong heat, and the dry residue being 
mixed with water, was digested (in the cold) 
in muriatic acid. Awhile powder remained 
undissolved, which, being separated and ig- 
nited, weighed 13.04 grains. It possessed the 
following characters. 
(1.) When heated before the blow-pipe 
with nitrate of cobalt, it assumed a beautiful 
blue colour. 
(2.) It dissolved by heat in sulphuric acid, 
and the solution being mixed with a solution 
of sulphate of ammonia, yielded crystals of 
alum. The powder then was alumina. 
7. The muriatic acid solution being super- 
saturated with carbonate of ammonia, white 
precipitate fell, which being separated and ig- 
nited, possessed the characters of alumina, and 
weighed 17.45 grains. 
Thus, the whole alunina extracted from the 
mineral was 30.49 grains. 
8. The dark red precipitate which was col- 
lected on the filter (in paragraphs) being 
dried and ignited, weighed 50’53 grains, 
9. It was digested in muriatic acid. The 
whole dissolved except a white powder 
weighing 0-996 grains. It was silica slightly 
impregnated with iron. 
10. The muriatic acid solution was mixed 
with carbonate of ammonia till it was render- 
ed as neutral as possible ; indeed a few flocks 
had precipitated. It was then heated in a 
flask. Carbonic acid gas escaped in abun- 
dance, and the whole peroxide of iron was 
precipitated. 'I’he whole was thrown on a 
filter, the oxide of iron was collected on the 
filter and washed ; the colourless solution 
which passed through being mixed with car- 
boiiate of ammoi\ia, a white'precipitatee fell, 
which became brown by strong ignition, and 
possessed the character of oxide of’ manganese. 
It was equivalent to 7*76 grains of protoxide 
of manganese. 
11. I'he peroxide of iron remaining on the 
filter being dried and ignited, weighed 
41 ‘774 grains. 
From the preceding analysis the constituents 
of dysluite appear to be 
Atoms. 
Alumina 
30*490 
13-55 
8* 
Oxide of zinc 
16-800 
3-2 
1*89 
Peroxide of iron 
41*774 
8*38 
4-6 
-Protoxide of manganese. 
7-760 
1-69 
1- 
Silica 
2*996 
1*498 
0 88 
Water 
0-400 
10012 
If we admit the silica to be only an acci- 
dental mixture, it is evident that dysluite con- 
sist ot 
8 atoms alumina 
2 ,, oxide of zinc 
5 ,, peroxide of iron 
1 ,, protoxide of manganese. 
The alumina obviously acts the part of an 
acid, as it does in spinell, automolite, sap- 
phirine, and candite. But in all of these, 
several atoms of alumina unite with one of the 
basis, which are manganese and peroxide of 
iron. But dysluite is composed of simple alu- 
minates, the formulaexhihiiing its constitution, 
being 
5/ Al. X 2 Z Al. X mn Al. 
It is worthy of remark, that the crystalline 
from of dysluite is tlie regular octahedron, 
the same from which spinell and all the other 
crystallized minerals, in which alumina acts 
the part of an acid, assume. 
A'ofe. — d'he four minerals mentioned, in 
which alumina acts the part of an acid in 
union with a base, have their composition 
represented by the following formulae, as de- 
duced from analyses made in the laboratory 
at Glasgow. 
1 Spinelle, Sp. Gr. 3-5-23 M Al.‘ 
2 Sapphirine ,, 3 4-28 2 M Al.*^ -f MS 
3 Candite ,, 3*617 8 Al A 1 .2 4 * 5/Al.« i 
4 Automalie ,, 4 261 Z Al.* 
To which may 
be added Chry- 
soveryl „ 3*711 GGl. A1.*4-/A1 .Ti 
Records of Science 1835. 
PHILOSOPHICAL TRANSACTIONS. 
Fon 1834, PART II. 
(Continued from p, 20.) 
II. INTENSITY NECESSARY FOR 
ELECTROLYZATION, -In this part of 
the paper the author demonstrates tliat by 
producing a current by the action of sulphuric 
acid upon amalgamated zinc in one vessel, 
passing it through acid in a second vessel by 
platinunn electrodes, a current may pass for a 
long period, but may be of so low an intensi- 
ty, as to fall below that degrea at which the 
elements of water una.ssisted by any auxiliary 
force capable ot forming a combination with 
the matter of electrodes, separated from each 
other. He found that a solution of sulphate 
of soda can conduct a current of electricity in- 
capable of decomposing the neutral salt pre- 
sent ; that _ this salt, in a state of so- 
lution, requires a particular intensity for the 
separation of its elements, and that the requi- 
site intensity is superior to that necessary for 
the decomposition of iodide of potassium 
likewise m solution, Fu.sed chloride of lead 
can also conduct a current having an intensi- 
ty below that required to effect decomposition. 
Fused chloride of silver is decomposed by a* 
similar current. A drop of water and fused 
nitre conducted a current without decompo- 
sition, It appears, farther, that the necessa- 
ly electrolytic intensity for water, is the 
same whether it be pure, or rendered a belter 
conductor by the addition of acids, for the 
power of acids, alkalies, salts, and other 
bodies in solution to increase conducting 
power, appears to hold good only where the 
