Rodolfo Amedeo Lanciani.

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large quantity of strong alcohol The resulting oxalate was
beautiriilly crystalline, and the precipitation was so complete
that SH, gave in the filtrate a scarcely perceptible yellowish
tinge. The oxalate was washed with alcohol by Bunsen's
method and dried at 110** C, until every trace of alcohol was
expelled. The filter was then pierced with a glass rod, and
the cadmic oxalate washed into a flask with hot diluted sul-
phuric acid. A few cubic centimeters of strong sulphuric acid
were then added, and the hot solution titrated with potassic
hypermanganate. In this manner four experiments gave 4419
pr. ct, 44*66 pr. ct, 44*88 pr. ct, and 44*2y pr. ct of cadmium,
as computed fi-om the oxalic acid. These results are all much
too high, and show that the acid had acted sensibly upon the
filter. Two other experiments were then mada In the first
a hot solution of ammonic sulphate was used as a solvent for
the oxalate ; in the second hot dilute chlorhydric acid was em-
ployed. Of the hypermanganic solution employed 100 c. c.
contained 0*1108 gr. of available oxygen.

L 0*4380 gr. cadmic sulphate required 24*5 c.o. hypermanganate

= 43*68 pr. ct. CcL
n. 0*8724 gr. cadmic sulphate required 21*1 c.c. hypermanganate
= 48*74 pr. ct. Cd.

The received formula 8CdS0^ +8H3O requires 48*75 pr. ct In
these two analyses the filters were not broken.

Barium, — Baric chlorid gave extremelv variable results in
my first experiment, notwitfiatanding the fact that the barium
is completely precipitated by oxabc acid and alcohol. The
resulting oxalate, after washing and drying, was not completely
decomposed by sulphuric acid, which appeared to form a crust
erf banc sulphate upon the crystals of the oxalate. This diffi-
culty was finally overcome by dissolving the baric oxalate in
chlorhydric acid and diluting the solution lai^ely. In this
manner:

0*6606 gr. baric chlorid required 80 c.c. hypermanganate == 66*21
pr. ct Ba (100 c.c. hypermanganate solution contained 0*058
gr. available oxygen). The formula BaCl, + 2H2O, requires
56*15 pr. ct. Ba.

Strontium. — ^To avoid the use of paper filters so as to be
able to employ sulphuric acid as a solvent, I resorted to sand
filters. A light fdnnel was ground truly conical near the throat
A little pear of glass with a long stem was then dropped into
the funnel, stem upward. In this manner a valve was formed
impassible to the sand laid upon the baU of the glass, but
allowing liquids to pass fireely. By means of the stem the valve



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242 W. Q. Leison — Predpitation and Determmatioti

oould be lifted from its seat, and the sand and precipitate
washed together into a flask, after carefal drying. With this
arrangement :

0*4292 gr. etrontio nitrate required 4Y'8 cc. hypermanganate =
48-90 pr. ct. SrO.

0'8667 gr. strontio nitrate required 40*8 c.c. hypermanganate =
48*90 pr. ct SrO. (100 c.c. hypermanganate solution con-
tained 0*1099 gr. available oxygen.)

The formula Sr(N03), requires 48*98 pr. ct SrO. Sulphuric
acid only was used to decompose the oxalate.

Calcium. — ^Iceland spar was dissolved in chlorhydric acid,
and the solution treated with oxalic acid and alcohol The fil-
trate contained calcium. When, however, the solution was
evaporated to dryness before adding alcohol, and the oxalate
was washed on a sand filter, no traces of calcium could be de-
tected in the filtrata In this manner :

0*6090 gr. CaCOg required 70*6 cc. hypermanganate = 66*10 pr. ct

CaO. (100 cc. hypermanganate corresponded to 0*11669 gr.

oxygen.)
0*6690 gr. CaCO, required 77*6 cc hypermanganate = 66*08 pr. ct

CaO. noo cc hypermanganate corresponded to 0*11496 gr.

oxygea)

The formula requires 56*00 pr. ct CaO. Sulphuric add only
was employed.

Magnesium. —When magnesic sulphate is treated with oxalic
acid, the mixture evaporated, but not to dryness, and alcohol
added, the filtrate is perfectly fi-ee fix)m magnesium. In this
manner:

0*8243 gr. MgSO. + 7H,0 required 89*6 cc hypermanganate =

16*18 pr. ct MgO.
0*3949 gr. MgSO. + 7HgO required 48*4 cc hypermanganate =

16*26 pr. ct MgO.

In these analyses the oxalate was collected on a paper filter
and washed into the fiask with water after pierciM the filter,
which was washed with cold dilute sulphuric acid. Tne formula
requires 16*26 pr. ct

^inc — Zinc is completely thrown down firom its sulphate by
the unmodified process. The oxalate forms an extremely fine
powder. A sand filter and warm dilute sulphuric acia were
employed.

0*9301 gr. sulphate required 47*1 c.c hypermanganate = 28*14

pr. ct ZnO.
1*0788 gr. sulphate required 64*6 cc hypermanganate = 28*16

pr. ct. ZnO.

The formula reqxdres 28*22 pr. ct ZnO.



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of ike Metals of the Magnesutm Group. 243

CobaU, — Perfectly pure anhydrous cobaltous chlorid was pre-
pared by igniting cnlorid of purpnreo-cobalt The chlorid was
then precipitated by oxalic acid and alcohol, collected on a sand
filter and digested with dilute sulphuric acid. The solution
was intensely red. A solution of mckelous sulphate was then
added, until the red color disappeared and a faint smoky hue
took its placa* In this manner :

0*4292 gr. CoCla required 47*8 c.c. hypermanganate = 46*30 pr. ct

Co.
0*3667 gr. C0CI2 required 40*8 c.c. hypermanganate = 46-37 pr. ct.

Co.

The formula requires 45*88 pr. ct (Co = 59).

Nickel — ^In the case of mckelous sulphate it was found nec-
essary, after adding the oxalic acid, to concentrate the mixture
on a water bath before adding alcohol, and then farther digest
for about half an hour, replacing the alcohol as fest as it evap-
orated. The oxalate was collected on a paper filter, and, ^fter
washing, dissolved in ammonia on the filter. The filtrate was
then acidified with sulphuric acid, and the color finally dis-
charged by a solution of cobaltous sulphate. In this manner :

0*9686 gr. nickelous sulphate required 42*2 c.c. hypermanganate

= 28-57 pr. ct NiO.
1*0287 gr. nickelous sulphate required 45*3 c.c. hypermanganate

= 28*68 pr. ct NiO.

The formula NiSO^ + 6H,0 requires 28*24 pr. ct NiO (Ni =
68), but it is very difficult to obtain the sulphate in a perfectly
definite state of nydration.

Manganese. — Although manganese is completely precipitated
from its soluble salts by oxalic acid in the presence of alcohol,
my results with the method have not been satisfectory, owing
as I suppose to my not having a definite salt for analysis. The
following analyses show at any rate that closely corresponding
results can be obtained when the same substance is taken :

0*3760 gr. manganous oxalate required 30*60 c.c. hypermanganate

= 88*38 pr. ct MnO.
0*4013 gr. manganous oxalate required 32*66 c.c. hypermanganate

= 38*38 pr. ct MnO.

The salt 2CaMnO^ 4- 5Hj,0 when dried in air requires 87*77
pr. ct. MnO, while the salt analyzed was dried at 100° C. In
like manner two analyses of a sulphate, which had probably
absorbed a little water, gave 45*28 pr. ct and 45*29 pr. ct of
MnO. The crystallized sulphate MnSO^ + 7Hj,0 requires 46*67
pr. ct

* Comparoi as regards this method, W. Gibbs, in this Journal, voL xiv, p. 204.



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244 J, H, Talbot — Precipitation of Zinc and Manganese,

Iron, — Q-ood results could not be obtained by tbe application
of this method to the determination of iron, but I am not at
present able to assign the reason of the failure in this casa

To complete my work it remains for me to point out the
applicability of the process to the determination of the whole
quantity of oxygen contained in a number of bases present
together in solution — ^a problem which is sometimes of interest

Sulphates of Manganese, Magnesium, Nickel, Cobalt, Cad-
mium and Zinc in undetermined quantities were dissolved to-
gether in water, and the solution well shaken. Four portions,
of 100 C.C. each, were then taken, and the acid determined in
each by baric chlorid. In two other equal portions the bases
were precipitated as oxalates and titratea as abova The oxy-
gen in the acid was then calculated from the amount of baric
sulphata In this manner it was found that the oxygen in the
acid was to that in the mixed bases as 3 to 1 very nearly, the
precise ratio being in the one case as 0*054 is to 0018 and in
the other as 0O55 is to 0O18. Another e^)eriment was made
with a crysfedlized dolomite containing 0*45 pr. ct of insoluble
residua The lime, magnesia and iron were precipitated to-
gether, and titrated as oxalates ; the carbonic acid was deter-
mined by ignition. In this manner the oxygen of the add
was found to be to the oxygen in the bases as 34*48 is to 17 "28.
The bases after ignition amounted to 52*41 pr. ct

In another experiment with a dolomite from a different local-
ity containing 0*18 pr. ct of insoluble residue, the oxygen ratio
was found to be as 84*56 is to 17*28, the bases amounting to 52-38
pr. ct If we calculate the relative quantities of calcic and
magnesic carbonates from the sum of the two oxyds in the last
analysis and the oxygen found by titrating the oxalate, we find :

MgCOg .... 42*77

CaCOj 57-07

InsoL residue - - 0*13

99*97
the small (juantity of ferrous oxyd present being neglected.
This analysis will serve to show the applicability of the method
in indirect analvses. My results appear to me to ftimish a gen-
eralization of the use of potassic nypermanganate, which will
be received with favor bv those who employ this reagent fi^
quently in volumetric analyses.

§2.

On new analytical processes ; by J. H. Talbott.

1. On the precipitation of zinc and manganese as sulphids.—
Zinc is thrown down from cold solution by an alkaline sulphid
in the form of a slimy mass which settles slowly and is ex-



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J. H. Talbot — Precipitation of Zinc and Manganese, 245

tremely difficult to wasL The precipitation is, however, more
complete than when sodic carbonate is used, and may be ren-
dered very easv and rapid by the following process : The solu-
tion of zinc, it acid, is to be neutralized as nearly as possible
by sodic or ammonic carbonata To the boiling solution sodic
or ammonic sulphid is to be added, a large excess being very
carefully avoids! The white precipitate, on continued boiling,
soon becomes granular, and settles readily. The supernatant,
clear liquid is then to be tested with a drop of the alkaline sul-
phid, to be sure of complete precipitation, and the sulphid
then washed with hot water by Bunsen's method. The filtrate
is perfectly clear, and absolutely fi^ee fix)m zinc ; the washing is
easy and rapid. The sulphid of zinc is then to be partially
dried with tne filter, in the manner recommended by JBunsen,
brought into a porcelain crucible and ignited, at first gently,
and afterward strongly with firee access of air. The expulsion
of the last traces of sulphuric acid is much facilitated by occa-
sionally dropping fragments of anmionic carbonate into the
crucibla Pure ZnO finally remains, the ignition being contin-
ued until a constant weight is obtained. In this manner the
following results were obtained :

0-3216 gr. pure ZnO gave 0-3216 gr. = 100-00 pr. ct.
0-3208 gr. " " " 0-8209 gr. = 10003 pr. ct.
0-2412 gr. " " " 0-2410 gr. = 09-91 pr. ct.
0-1786 gr. ** " " 0-1784 gr.= 99-94 pr. ct

In zincic sulphate, which had probably lost a little water:

0-6486 gr. gave 0*1861 gr. ZnO = 28-64 pr. ct
0-6610 gr. " 0-1868 gr. " = 28-64 pr. ot
0-8198 gr. " 0-2338 gr. " = 28-62 pr. ct

The formula requires 28*29 pr. ct ZnO. The advantages of
this process over the older methods of precipitating in the cold
are, I think, very evident, even if only the saving of time be
taken into consideration.

Manganese may be precipitated completely fix)m its boiling
solutions by precisely the same procesa The flesh-colorea
sulphid is granular and sometimes even sandy, though not
distinctiy crystalline, and may be washed with the utmost
fecility. The precipitated sulphid, after washing upon a filter,
is to DC redissolvea in chlorhydric acid, and precipitated as
anmaonio-phosphate in the manner proposed by Prof Gibba
To test the method with a perfectly definite salt of manganese,
manganous pyrophosphate was selected, dissolved in dilute
chlomydrio acid, and the solution nearly neutralized by sodic
carbonata To the boiling solution sodic sulphid was then
added, and tiie manganese finally weighed — ^in one analysis as



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246 J. H, Talbot — Separation of Tin and Tungsten.

pyrophosphate, in another as anhydrous sulphid by ignition
m a cnrrrent of SH^. In this manner :

0-3132 gr. MngPaO, gave 0-3126 gr. Mn^PaOy = 49-66 pr. ct

MnO.
0-3786 gr. Mn^PgO, gave 0-2310 gr. MnS = 49*66 pr. ot MnO.

The formula requires 49*64 pr. ct MnO. It is perhaps worthy
of notice that ammonic sulphid does not completely decompose
maiiganous pyrophosphate under the circumstances above de-
scribed. The greater portion of the salt is precipitated at once
as crystalline ammonio-phosphate of manganese.

2, On Hie qtcantitative separation of tin and tungsten.
The quantitative separation of tin firom tungsten has always
been regarded as a difficult problem not hitherto solved in a
satisfactory manner. The following method will, I think, be
found to leave nothing to be desired as respects both ease and
accuracy. It depends upon the fact that stannic oxyd, SnO,,
is reduced by potassic cyanid with great facility, while tungstic
acid, WO 3, undergoes no reduction, even when heated with the
cyanid to a high temperatura The oxyds of tin and tungsten
are to be heated in a porcelain crucible with 8 or 4 times their
weight of commercial potassic cyanid, previously ftised, pulver-
ized, and thoroughly mixed with the two oxyds. The mass is
kept fused for a short time, when the tin separates in the form
of metallic globules, while the tungstic acid unites with the
alkali of the potassic cyanate and carbonate present After
cooling, the mass is to oe treated with hot water, which dis-
solves the alkaline tungstate and other salts, and leaves the tin
as metal This is to be filtered off, washed^ dried and weighed
as stannic oxyd after oxydation in the crucible with nitric acid.
The tungstic acid is most conveniently estimated by the differ-
ence, but may of course be precipitated by mercurous nitrate,
after boiling the solution with nitric acid to decompose the ex-
cess of potassic cyanid present, and then redissolvmg the pre-
cipitatea tungstic acid oy means of an alkali. To test the
method, weighed portions of pure stannic and tungstic oxyds
were mixed and treated as above :

0-6662 gr. SnOg and 0*6880 gr. WO3 gave 0*6679 gr. SnO^ =
63*24 pr. ct The calculated percentage of stannic oxyd is
here 63*11.

0-7098 gr. SnOj, and 0*6460 gr. WO 3 gave 0*7096 gr. SnO, =
66*61 pr. ct, the calculated percentage being 66*52.

0-6378 gr. SnO, and 0*4373 gr. WO3 gave 0-6406 gr. SnO^ =
66-43 pr. ct., the calculated percentage being 66*16.

0*6073 gr. SnOa and 0*4334 gr. WO3 gave 0*6081 gr. SnO^ and
0*4349 gr. WO 3. This corresponds to



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T. if. ChcUard — li'eatnimt of Gelatinous Precipitates. 247

Found. OaloulatecL

Stannic oxyd, 64-01 63-92

Tungstic oxyd, 46-23 46*08



100-24 100-00

As it mifflit perhap be objected to the examples given above
that I employed only purely mechanical mixtures of stannic
and tungstic acids, and that this is not the case which occurs in
practice, I made the foUowii^ additional analyses : Portions of
the two metallic oxyds were rased in a silver crucible with pure
sodic hydrate ; the fused mass was then dissolved in water and
the two oxyds precipitated together from the solution by nitric
acid with the usual precautions. The ignited mixed oxyds
were then fused with potassic cyanid, as abova In this man-
ner:

0'Y292 gr. of a mixture of SnOa and WO3 gave 0-4211 gr. SnO^

= 67-74 pr. ct.
0-9826 gr. of the same gave 0-6661 gr. SnOj, = 67'61 pr. ct

Tin cannot be separated from molybdenum by fusing the
mixed oxyds with potassic cyanid, as the molybdic acid is
always more or less completely reduced to a lower oxyd.

§8.

On the treatment of gdaiinous precipitates; by Thomas M.
Chatabd.

The inconveniences and loss of time which attend the wash-
ing of gelatinous precipitates are femiliar to all chemists. Even
the methods of washing recently introduced by Bunsen are not
always perfectly satisfactory in their operation when applied
to this class of substances. The following method will be
found, I think, to give results which leave nothing to be de-
sired : The solution containing the substance to be determined
is to be simply evaporated to perfect dryness with a small ex-
cess of the precipitant, and the gelatinous mass stirred with a
rod until it becomes a perfectly dry powder. In this manner
the precipitate diminishes extremely m bulk, and may then be
wasned with the greatest ease upon the filter. The evaporation
is usually eflEected with suflBcient rapidity on a water bath. The
following analyses will be sufBcient to show the degree of pre-
cision attainable by this process in the cases of some of the
more familiar precipitates: Weighed portions of potassic di-
chromate were dissolved in very small portions of water, re-
duced with chlorhydric acid and alcohol, the excess of alcohol
expelled, and ammonia added in excess. After evaporation, in
the manner above described, the chromic sesquioxyd presented
a greenish blue granular powder very easily wash^



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248 S, P. Sharpies — Precipitation of Antimonous Sulphid.

0-7782 gr. KaCraO, gave 0-4028 gr. CraO, = 68*02 pr. ct. chro-
mic acid.

1-6646 gr. KgCraO, gave 08102 gr. Cr^Oj = 68-13 pr. ot chro-
mic acid.

The formula requires 68'04 pr. ct

Alumina treated in the same manner is also very easy to
wasL

2-4097 gr. potassic alum gave 0-2626 gr. Al,Oj = 10-89 pr. ct.
1-9571 gr. « " " 0-2180 gr. « = 10-88 pr. ct.

The formula requires 10-86 pr. ct

The process applies with almost equal advantage to iron.
Weight portions of ammonio-ferrous sulphate were oiEsolved in
water, ana sodic chlorid added in large excess to furnish solid
matter to be washed out The iron Was then oxydized with
nitric acid, precipitated by anmionia, and evaporated as above

1-5824 gr. gave 0-8229 gr. Fe^Og = 14-28 pr. ct Iron.
1-4840 gr. gave 0*8019 gr. " = 14-24 pr. ct Iron.

The formula requires 14-29 pr. ct

Nickelous carbonate also loses its gelatinous character when
treated as above. 0*2201 gr. metalhc nickel gave, after solu-
tion, precipitation as carbonate, and reduction by hydrogen,
0-2199 gr. metallic nickel = 99-91 pr. ct of tiie quantity taken.
Cobaltous carbonate may be treat^ in the same manner, but
the alkali cannot be completely washed out, and the method is
in this case not to be recommended.

It seems at least extremely probable that other gelatinous
oxyds and hydrates will give equally good results when treated
in the manner which I have described.

§4.

On the precipitation of anUmorums sulphid from boiling solutions ;
by Stephen P. SHABPLEa

In the precipitation of antimonous sulphid I have found it
of very great advantage to employ the following process : tito
the solution, containing as usual tartaric and fiee chlorhjdric
acid, a current of sulphydric acid gas is to be passed, the hquid
being, during the passage of the gas, gradually heated to Ae
boiling point The boiunjg is then to be continued for 15 or
20 minutes, the current of gas passing uninterruptedly, until
the voluminous sulphid has become a dense granular powder,
oocupjing but a small portion of the original volume of the
sulphid. The sulphid may then be washM with great facility,
and dried upon a sand filter at 200^^800'' C. All the deter-
minations 01 antimony made in this Laboratory for some years
have been executed in this manner, the results leaving nothing



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R Qodvnn — Repetition m chemical analysis. 249

to be desired. Arsenous sulphid does not become granular
and dense under the same circumstances. In this connection I
may be permitted to mention that the sulphids of nickel and
cobalt, when precipitated from boiling solutions in the manner
recommended by Prof Gibbs some years since, should be fil-
tered off, and washed immediately after precipitation. In this
manner there is no oxydation upon the filter, even during the
drying of the precipitate. But if the sulphids are allow^ to
stand in the solution from which they have been precipitated,
for even a few hours, they will usually oxydize upon the filter
during the washing.

§5.

On the introduction of the principle of repetition into chemical
analysis; by Bryant Godwin.

The method of repetition, so fi-equently and so advantageously
employed in physical investigations, has not, so far as I am
aware, been applied to chemical analysis. It seems at least de-
sirable that it should be so applied, and I will here give a par-
ticular instance in which it may be employed with advantage.
In the determination of iron 6y means of potassic hyperman-
ganate, all the iron is, at the end of the operation, in the form
of sesquioxyd, while there is also a very small excess of unre-
duced hypermanganate. When the solution is boiled for a
short time with pure zinc-dust and then filtered through a
ribbed filter, which is quickly washed with water previously
boiled to expel air, the iron is wholly in the form of ferrous
oxvd, and the process of titration may be repeated a second time..
After a new reduction the iron may again be determined, and
this process may be repeated until the volume of liquid becomes,
too large to be easily handled. The following analyses werQ
made to test this process :

0-4725 gr. ammonio-ferrous sulphate required in 5 successive titra-
tions 49*0, 47*2, 48*7, 48*0, 48'5 cubic centimeters of potassic
hypermz^nganate, 1 cc. corresponding to 0*0014 gr. iron,
llie mean of these 5 determinations gives 14*31 pr. ct. iron in
the salt.

0*4888 gr. required in 7 successive titrations 49*6, 48*75, 60'5j 49*8,
49*7, 49*8, 49*6 c.c. of hypermanganate, the mean of which
gives 14*23 pr. ct. iron.

The formula requires 14*27 pr. ct

These analyses, which witn more practice and experience on
my part would doubtless have corresponded much more closely,
will at least serve to show that the principle of repeated obser-
vations of the same quantity to be measured may sometimes be
introduced into chemical analysis.
Am. Jour. Bol— Sbgokd Sbbixs, Vol. I«, No. 149.— 8spt., 1870.
16



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260 IT. A. Norton on the Oorona $em in JEcUpiea of Ae Sun.



Art. XXYL—On the Oorona seen in Total Edipees of the Sun;
by Professor W. A. Norton.

Cbrtain observations made on the total ecjipse of the snn
of August 7, 1869, have led some of the observers to the con-
clusion that the corona seen on that occasion, and in previous
eclipses, is of the nature of a Solar Aurora. It is jHX)per that
it should be publicly stated that this theory is not a new one.
It has been advocated for several vears by the author of the
present communication, both in publications and in public lec-
tures. It is essentially involved in the explanation of the
Zodiacal Light, propounded in his Treatise on Astronomy, 2nd
edit (1845) ; ana in the theoretical views set forth in a note
appended to the discussion of the topic of Terrestrial Magnet-
ism, in a memoir on Molecular Physics, published in this Jour-
nal (1864-6).* It is distinctly presentea in the last edition of
the Treatise on Astronomjr (1867), pp. 172, 174, 175, and 17&
I propose, in a communication to tne next No. of this Journal,
to state the principal ^rounds upon which I have maintained
the auroral origin of the corona in diflferent publications, as
well as give the results of my own observations on the eclipse
of 1869, and of those of other observers of that and previous
total eclipses, which lend a powerful support to the auroral
theory of the corona.

This introductory notice is now published mainly with the
view of calling, at an early day, the attention of astronomers
who mar observe the eclipse of December next, to the impor-
tance of noting the exact positions, with respect to the plane of
the sun's equator, of the more prominent portions of the cor-
ona. From two to four points of special outstreaming have
been observed in different eclipses. In the eclipse of laSt year
the more conspicuous extensions of the corona were nearly in
the plane of the sun's equator, and from the vicinitv of the
poles. The figure of the corona, accompanying the Keport of
r. Prof Capelotti of observations on the eclipse of April 15,



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