128 
MAGNETISM. 
the needle firft became weaker, then neutral, and then 
turned into the oppofite pofition. Dr. Robifon explained 
this curious phenomenon by what he calls primary and 
lecondary magnetic curves, fuch as N H M, N E L, and 
S G K, SEI ; but our limits do not permit us to enter 
here on the inveftigation of thefe curves. 
Analogy between Magnetism and Galvanism. 
Of fome particulars wherein the phenomena of magne- 
tifm were analogous to thofe of Electricity, we have 
fpoken under that article, vol. vi. p. 434. but fome late 
experiments of Mr. Ritter tend to (how a greater analogy 
than has yet been fifppoffed, between magnetifm and that 
modification of eleffricity which we call galvanifm. 
Ritter’s firft experiments with the magnet were on frogs. 
He found that a magnetic iron wire, with another not 
magnetic, excited a galvanic palpitation in thefe animals. 
Prefently he obferved, that the fouth pole excited ftronger 
palpitations, and the north pole weaker, than the iron 
not magnetic. Having conffantly noticed, that the me¬ 
tals molt fufceptible of oxydation excited the ftrongeft 
palpitations, he inferred, that the fouth pole pofleff'es a 
greater affinity for oxygen than fimpleiron, and the north 
pole lefs. This fuppofition he confirmed by means of fe- 
veral chemical re-agents. He placed a magnetic iron- 
wire on pieces of glafs in a plate of earthen ware, and 
poured upon it a very weak nitric acid. The fouth pole 
was attacked by the acid much more powerfully than the 
north ; and was foon furrounded by a depofition of oxy¬ 
gen, the quantity of which greatly exceeded that of the 
other pole. The different oxydability of the magnetic 
poles is very well exhibited likewifefby taking three fmall 
bottles of equal fize, filled with water, either pure or 
llightly acidulated, and putting into one the fouth polar 
end of a magnetic wire, into a fecond the north polar end 
of a fimilar wire, and into the third the end of an equal 
wire not magnetic; the fouth pole will firft begin to de- 
pofit oxyd, the unmagnetic iron a little after, and the 
north pole laft. This experiment requires confiderable 
care. The furface of the water muff be covered with very 
freffi oil of almonds, to exclude all accefs of air. Care 
muff be taken too, that one of the bottles is not more ex- 
pofed to the fun than the others, becaufe light accelerates 
oxydation. Ritter convinced hiinfelf of this by direft 
experiments; expofing two iron wires in water to the fun, 
but covering one of the phials with black paper, when 
that in the phial left uncovered was oxydated much more 
quickly. 
The analogy between galvanifm and magnetifm is ftill 
farther proved by other experiments of Ritter on galva¬ 
nizing metals, which he does by placing them in a ftream 
of galvanic fluid proceeding from a ftrong pile. Hefound 
that a golden needle thus galvanifed and balanced on a 
pivot, exhibited, like a magnetifed iron needle, both di¬ 
rective power and horizontal inclination. 
Some late experiments of Ritter, referring ftill more di¬ 
rectly to the analogy between magnetifm and galvanifm, 
were communicated to the Royal Academy of Sciences 
of Munich, and the following are their general refults. 
1. Every magnet is equivalent to a pair of heterogeneous 
metals united together; its different poles reprefent as it 
were different metals. 2. Like them, it gives eleffricity; 
that is to fay, one of the two poles, the pofitive eleffricity, 
and the other the negative. 3. By following the fame 
procefs, a certain number of magnets, as well as a certain 
number of pairs of metals, afforded eleffricity ; and in 
this manner the electricities afforded by the poles of dif¬ 
ferent magnets, have been fuccefsfully indicated by the 
eleftrometer. 4. By means of thefe electricities, one of 
thefe batteries of magnets, accordingly as it is more or lefs 
ftrong, produces upon dead and living bodies all the phe¬ 
nomena which are produced by a pile of Volta, of the 
•common kind, and of the fame force. 5. The experiments 
which prove this, fliow that, in magnetifed iron, the 
fouth pole gives pofitive eleffricity, and the north pole 
negative eleffricity; but that, on the contrary, in magne¬ 
tifed fteel, the north pole affords the pofitive, and the fouth 
pole the negative. 6. The fameinverfe difpofition isalfo 
obferved with regard to the polar oxydability of the mag¬ 
netifed body in which this change is produced by mag¬ 
netifm. In magnetifed iron the fouth pole is molt oxyda- 
ble, and the north pole leaft ; whereas in magnetifed 
fteel the north pole is molt oxydable, and the louth leaft. 
7. Mr. Ritter thinks that, by confidering the earth as an 
immenfe magnet, thefe refults might ferve to explain va¬ 
rious phenomena of nature, fuch as the phyfical difference 
between the two hemifpheres, the aurora borealis and au¬ 
rora auftralis. In faff, after what has been juft ltated, the 
earth, conlidered as a magnet, may be taken as an equiva¬ 
lent to an immenfe pile of Volta, of which the poles are 
on one fide fufficiently clofed by the waters of the ocean. 
And the affion of this pile muff produce, and has pro¬ 
duced, the greateft chemical changes in the materials of 
the earth ; changes which muff have differed according 
to the poles ; and of which pile the poles at the other 
extremity have always fuch an abundance of eleffricity 
as to caufe its fplendour to appear by radiations in the 
valt fpaces of the heavens. 
The principal works on the magnet are, a treatife de 
Magnete by Gilbert, an Englifh philofopher, printed in 1600: 
it contains traces of that fpirit of obfervation which has 
fince caufed philofophy to make fo great a progrefs. The 
Ars Magnetica of Kircher; this is a kind of encyclopaedia 
of every thing written before the author’s time on that 
fubjeff, enlarged by a great many of his own ideas, the 
greater part of which however dilplay more imagination 
than judgment. The Magnetologia of Father Leothaud, 
1668, in 4to. a work of very little importance. Father 
Scarella’s treatife, entitled de Magnete, in four volumes 
quarto, printed at Brefcia, in 1759, may fupply the place 
of all the preceding, as it contains a comprehenfive ac¬ 
count of everything ufeful or folid, faid or written on the 
magnet, till that period ; to which the author, a very- 
enlightened philofopher, has added his own ideas. Mr. 
Cavallo’s Treatife on Magnetifm, firft publifhed in 1787, 
contains a great variety of faffs and experiments ; and a 
neat compendium of it is given in the 3d volume of the 
fame author’s Elements of Natural and Experimental Phi¬ 
lofophy. Mr. Cavallo’s Treatife, and Mr. Adams’s Effay 
on Magnetifm, form the fubftance of molt of the compila¬ 
tions on this fubjeff that have lately appeared. 
Animal Magnetism, a fympathy fuppofed by fome 
perfons to exift between the magnet and the human body ; 
by means of which the former, it was thought, poffelfed 
the property of curing many difeafes. See the article 
Juggling, vol. xi. p.493. 
M AGNI'CO. See Manica. 
MAGNICOU'RT, a town of France, in the department 
of the Straits of Calais : fix miles fouth-eaft of St. Pol. 
MAGNIFI'ABLE, adj. [from magnify .] Worthy to 
be extolled or praifed. Unufual.—Number, though won¬ 
derful in itfelf, and fufficiently magnfable from its de- 
monftrableaffeffions, hath yet received adjecfions from the 
multiplying conceits of men. Brown's Vulgar Errours. 
MAGNIF'IC, or Magnif'ical, adj. \_magnificus, Lat.} 
Illultrious ; grand ; great; noble. Proper, but little ufed. 
—The houfe that is to be builded for the Lord muff: be ex¬ 
ceeding magnificat, of fame and glory throughout all coun¬ 
tries. 1 Chron. xxii. 5. 
O parent! thefe are thy magnijlc deeds ; 
Thy trophies! Milton’s Faradife Lojl. 
MAGNIF'ICENCE, f. [magnificentia, Lat.] Grandeur 
of appearance; fplendour.— One may obferve more fplen¬ 
dour and magnificence in particular perfons’ honfes in Ge¬ 
noa, than in thofe that belong to the public. Addifon. 
This defert foil 
Wants not her hidden luftre, gems and gold. 
Nor want we fkill or art, from whence to raife 
Magnificence. Milton's Paradife Lof. 
a WAGNIF'ICENT, 
