magne-crystallic 
+ -i.] Pertaining to the effect of a magnet 
upon a crystallized body. Faraday called the mag- 
netic force whose action upon crystals was determined by 
their molecular structure magiie-cryxtailic .force. Tyndall 
shows that in paramagnetic crystals the axis (magm-crys- 
tallic axii) sets axially ; in diamagnetic crystals, equatori- 
ally. 
The flrst observations of the magnecrystallic couple were 
made by Pliicker. . . . Shortly after Plucker's first results 
were published, Faraday discovered the magnecrystallic 
action of crystallized bismuth. 
O. Chrystal, Encyc. Brit., XV. 264. 
magnelt, A Middle English variant of man- 
gonel. 
magnesia (mag-ne'sia), . [ME. magntHM (def. 
] ) ; < ML. /fl<7ew/,~a"mineral said to be brought 
from Magnesia; fern, of Magnesias, adj., per- 
taining to Magnesia, < Magnesia, Gr. Mayvt/aia, 
a district in Thessaly (also the name of two 
cities in Asia Minor) : see magnet. In def. 2 = 
F. magnesie = Sp. Pg. It. magnesia, NL. mag- 
nesia, magnesia (magnesium oxid), so called 
from a supposed relation to manganese (for- 
merly called magnesium).] If. A mineral said 
to be brought from Magnesia. 2. Magnesium 
oxid (MgO), a white tasteless substance hav- 
ing a feeble alkaline reaction, its specific gravity 
varies from 3.07 to 3.61. It is nearly insoluble in water, 
and scarcely fuses at the temperature of the oxyhydro- 
gen flame. It is prepared by the ignition of any magnesium 
salt of a volatile acid. Magnesia is used in medicine 
as an antacid and mild cathartic, and in the arts for pre- 
paring magnesium salts. Magnesia alba, the magnesia of 
the shops, is a hydrated magnesium carbonate. Calcined 
magnesia, is pure magnesia prepared by strongly heating 
the carbonate. Magnesia mica. Same as biotite. 
Magnesian 1 (mag-ne'si-an), a. [< L. Magne- 
sia, < Gr. Mayw^oj'a, Magnesia (see def.), + -.] 
Of or pertaining to Magnesia, an ancient city 
of Asia Minor, near Miletus, or to a town of the 
same name in ancient Lydia, or to a district so 
called in Thessaly. 
magnesian 2 (mag-ne'gian), a. [< magnesia + 
-aw.] Pertaining to magnesia or having its 
qualities ; containing or resembling magnesia. 
Magnesian limestone. See limestone. 
magnesic (mag-ne'sik), a. [< magnesium + -/<.] 
Of or pertaining to magnesium. 
The tendency to fuse on the part of the mixture is due 
to the magnesic chloride. Ure, Diet., IV. 543. 
magnesioferrite (mag-ue"si-o-fer'it), n. [< 
NL. magnesium + L. ferrum, iron.] An oxid 
of magnesium and iron, belonging to the spinel 
group, which has been observed at Vesuvius. 
Also magnoferrite. 
magnesite (mag'ne-sit), n. [< magnesium + 
-ite 2 .] 1. Native magnesium carbon ate, a min- 
eral occurring in white compact masses, less 
often in rhombohedral crystals. It belongs to 
the calcite group. 2f. The hydrated magne- 
sium silicate usually called sepiolite or meer- 
schaum. 
magnesium (mag-ne'gium),n. [NL. ; in def. 1, 
< Gr. Maywjmo, sc. /U0o?, magnet ; in def. 2^ < mag- 
nesia, 2.] If. Manganese. 2. Chemical sym- 
bol, Mg; atomic weight, 24.4. The metallic base 
of the widely distributed alkaline earth magne- 
nesia, which in various combinations, and espe- 
cially in the form of the double carbonate of 
lime and magnesia, is one of the most abundant 
of the materials which make up the earth's crust. 
It is a metal of a brilliant silver- white color, having a spe- 
cific gravity of 1.75. It melts at a red heat, and boils at a 
temperature somewhat above that at which zinc volatilizes. 
When held in the flame of a candle it burns with a daz- 
zlingly white light, which has been seen at sea at a dis- 
tance of 28 miles. Magnesium was flrst prepared in a 
pure state by Bussy ; that which had been previously ob- 
tained by Davy was impure and not a coherent metal. It 
is now manufactured on a large scale at various places, 
especially near Manchester in England, and is pressed 
when in a semi-fluid state into wire, and then flattened 
into ribbon, in which form it is generally sold. It is used 
in taking photographs in places into which the sunlight 
does not penetrate, in signaling for naval and military 
purposes, and in pyrotechny, as well as in some operations 
connected with chemical analysis. The magnesian com- 
binations are widely distributed in nature. From 5 to 6 
per cent, of the solid material held in solution by the water 
of the ocean is magnesium sulphate, and from 8 to 11 
per cent, magnesium chlorid. Next to sodium, chlorin, 
and sulphuric acid, magnesium is the most abundant in- 
gredient in solution in the ocean. It is, with rare excep- 
tions (as in the case of the genus Serpula), not taken from 
the ocean by animal life, differing greatly in this respect 
from lime. Magnesium carbonate, in combination with 
calcium carbonate, forming dolomite, occurs in enormous 
quantity among the stratified formations. Beds made up 
of almost chemically pure dolomite hundreds of feet thick 
coyer thousands of square miles in the valley of the upper 
Mississippi. Magnesium carbonate also occurs in great 
abundance, mixed in varying proportions with the cal- 
cium carbonate, in much of the rock designated as marble 
and limestone, which, when this fact becomes known by 
chemical analysis, are denominated dolomitic. Magnesia 
also plays the part of base in great numbers of silicates. 
especially in talc, meerschaum, serpentine, olivine, and 
the pyroxenes and hornblendes. Magnesiau silicates form 
3574 
an important part of numerous meteorites. The pure 
magnesium carbonate (magnesite) occurs in various lo- 
calities, but is by no means an abundant mineral. The 
uon silicated soluble compounds of magnesia are also of 
rather rare occurrence in nature, but are found in con- 
siderable quantity in a few localities, among which that 
in the vicinity of Stassfurt in Prussia is economically of 
by far the greatest importance. The combinations found 
there are kainite, carnallite. and kieserite. (See these 
words.) Both magnesium sulphate and magnesium chlorid 
occur in the water of many mineral springs as well as in that 
of the ocean. The bones of animals and the seeds of vari- 
ous cereals contain a small amount of magnesium phos- 
phate, and the salt is also found in guano. Magnesian salts 
are used to a limited extent in medicine, especially the 
sulphate (Epsom salts) ; they are also used in dressing 
cotton goods and in dyeing ; but, on the whole, the econom- 
ical importance of the combinations of magnesium, con- 
sidering their abundance and the cheapness with which 
they could be furnished in large quantity, is exceedingly 
small. 
magnesium-lamp (mag-ne'sium-lamp), H. A 
lamp in which magnesium is burned for the 
purpose of illumination. Such lamps are of various 
types, being adapted for the combustion of the metal in 
the form of a wire or ribbon or in a pulverized state. 
magnes-stonet, . [Tr. L. magnes lapis, Gr. 
Majw/f Ai'Sof : see magnet.] A magnet. 
On thother syde an hideous Rocke is pight 
Of mightie Magnes ttone. Spenser, Y. Q., II. xii. 4. 
As if the sight of the enemy had been a magnes stone to 
his courage, he could not contain himself. 
Sir P. Sidney, Arcadia, iii. 
magnet (mag'net), . [< ME. magnele = D. maij- 
nci't = MHG. magnes, magnate, G. magnet = Dan. 
Sw. magnet = OF. magnete, mttnetc (the mod. F. 
term isaimant: see adamant, in/mant) = Sp. Pg. 
It. magnete, < L. magnes (magnet-) (with or with- 
out lapis, stone), a magnet, < Gr. //<4}i>, also 
/Myvrjaaa, prop, adj., M(iyw/f, Majviyrif, Mayvr/aia, 
Mayvi/aaa (sc. /.I6of), a magnet, lit. stone of 
Magnesia, < Mdjw/j (Mtiyvr/T-), also Ma-yvr/ri/c, 
an inhabitant of Magnesia, < Mnj -vi/aia, Mag- 
nesia, a district in Thessaly, where the magnet 
or magnetic iron ore appar. first came to no- 
tice.] A body which possesses the property 
of attracting fragments of iron or steel, and 
which, when freely suspended, tends, under 
the action of the earth, to take a certain defi- 
nite position, pointing approximately north 
and south. The lodestone, a variety of the mineral 
magnetite, or the native magnetic oxid of iron ( l'V :; < ) , i. is 
a natural magnet; but the properties of the magnet are 
best shown by an artificial magnet (see below), which has 
commonly the form of a straight bar or that of a horseshoe. 
When a bar-magnet is dipped into iron-filings, it is found 
that they adhere most strongly at the extremities of the 
bar (which are called the poles of the magnet), and not at 
all along the line midway between them. Strictly speak- 
ing, however, except in the case of a long thin magnet, the 
poles are not exactly at the ends. The middle line is called 
the neutral line or equator of the magnet; the straight line 
joining the poles is the axis of the magnet, or magnetic axis. 
A magnetic bar may abnormally have one or more inter- 
mediate points of maximum attraction, which are then 
Steel Magnet with consequent poles at a and 0. 
called consequent poles. Again, if a magnetic needle is 
suspended at its center of gravity so as to be entirely free 
to turn, it is found that in general it places itself with its 
axis in a direction nearly north and south, and with one 
end inclining downward. The pole which is directed to- 
ward the north is called the north or north-seeking pole, 
also the boreal, positive, or red pole, or marked end of the 
needle ; the other, the south, south-seeking, austral, nega- 
tive, or blue pole, or unmarked end. It is found, further, 
that the like poles of two magnets repel and unlike poles 
attract each other. If a magnet is broken into halves, 
each half is found to be a complete magnet with a north 
and a south pole; and this is true no matter how often 
the process of division is repeated. On this and other 
more fundamental grounds, it is concluded that the mag- 
netic polarity belongs to each molecule throughout the 
bar, and the maximum attraction observed near the ends 
is only the resultant effect of all these individual forces. 
(See magneti&n.) A magnetic substance is one which may 
be attracted by a magnet, but has not the property of 
attracting other magnetic substances, and therefore has 
no polarity. Soft iron is a magnetic substance, as is also 
most magnetite, the lodestone variety being exceptional. 
\pertiianent magnet is one which retains its magnetism 
after the magnetizing influences (see below) cease to act. 
Steel and the lodestone have this property, on account of 
their high degree of coerciveforce. (Seecoera'w.) Soft iron 
has very little coercive force, and accordingly its power of 
retaining magnetism is small. An artificial magnet (as a 
compass-needle)is made by contact with othermagnets, and 
the methods employed are described as single-tmicti, dmtW?- 
tmtch, and separate-touch, according to the way in which 
the substance to be magnetized is rubbed by the magnets. 
Such a magnet may also be made by magnetic induction 
without actual contact. (See induction, 6.) Again, a mag- 
net maybe made bypassing a currentof electricity through 
a wire wound about the bar to be magnetized; this is called 
an electromagnet (which see). By this means magnets of 
very great strength may be made. They have usually a 
horseshoe form, and the bar is of soft iron, so that it retains 
its magnetism only so long as the current is passing. The 
earth may he considered as a huge magnet, whose poles 
magnetic 
are situated in the neighborhood of the geographical poles, 
though not coinciding with them; the north magnetic pole 
of the earth corresponds in polarity to the south-seeking 
pole of a magnetic needle. The action of the earth causes a 
freely suspended needle to set in a plane called the mag- 
netic meridian, which in general makes an angle east or 
west of the geographical meridian (see declination), and 
with one pole (in the northern hemisphere, the north-seek- 
ing pole) inclined downward (see dip of the needle, under 
dip). The earth's magnetic force also serves to induce mag- 
netism in masses of iron lying in or near the magnetic 
meridian. An iron ship is thus magnetized in the course 
of its construction. Similarly, iron columns, etc., are often 
found to be feebly magnetic. Magnetic properties belong 
also to some other compounds of iron besides the mag- 
netic oxid, as pyrrhotite or magnetic pyrites (Fe7Sg), and to 
some varieties of the native sesquioxid. hematite (FeoO.-j); 
also to the magnetic metals nickel, cobalt, chromium, ami 
manganese. Some varieties of platinum are strongly mag- 
netic, and occasionally masses have polarity also, but this 
may be due to the large percentage of iron present, al- 
though all so-called iron-platinum does not show this prop- 
erty. Finally, it Is found that a powerful electromagnet 
exerts an effect on all substances, in accordance with which 
they are divided into the two groups paramagnetic and 
diamagnetic (this is explained under diamagnetwm). 
Compound magnet. Same as magnetic 
battery. Deflectmg-magnet, a magnet 
usedior deflecting a magnetic needle : often 
attached to a galvanometer for the purpose 
of fixing the zero of the needle in a certain 
position, or for altering the sensitiveness 
of the needle by changing the magnetic 
fleld. Also called zero magnet, 'directing- 
matjnet, and deflector. Horseshoe mag- 
net, a magnet having a form somewhat 
resembling a horseshoe (see figure), being 
bent so that the two poles are brought near 
together, and hence can act at the same time 
upon the keeper or armature. A horseshoe 
electromagnet commonly consists of two 
bobbins side by side, whose cores are con- 
nected at one end by a piece of soft iron. Moment of a 
magnet. See moment. Permanent magnet. See the 
definition. Portative force Of a magnet, the maxi- 
mum weight which a magnet can support. Receiving- 
magnet. Same as relay-magnet. Relay-magnet, or re- 
lay,m teleg., a sensitive electromagnetic receiving instru- 
ment used to close a circuit in the receiving station, which 
contains a battery and a less sensitive receiving instru- 
ment, such as a sounder or a register : also used to retrans- 
mit a message over another section of the line. See traim- 
late. Saturated magnet. See magnetism. Solenoi- 
dal magnet, a long ana thin bar-magnet, uniformly mag- 
netized, whose poles are at or very near the ends. In such 
a magnet the distribution of the magnetism is said to be 
solenoidal, in distinction from the lamellar distribution of a 
magnetic shell (which see, under magnetic). to arm a 
magnet. See on2. To make the magnet. Seenwrfr. 
magnetic (mag-net'ik), a. and n. [= F. mn- 
gnetique = Sp. magnetic = Pg. It. magnetic" 
(cf. D. Gr. magnetisch = Dan. Sw. magnetisli), < 
NL. magneticus (NGr. ^ayi^?r<5f), of a magnet. 
< L. magnes (magnet-), < Gr. ftayvrif (uayvrrr-}, 
a magnet: see magnet.] I. a. 1. Pertaining 
to the magnet or to magnetism ; possessing the 
properties of the magnet : as, a magnetic bar of 
iron; a magnetic needle. 
The magnetic axis of the magnet is the line joining the 
two poles, and the direction of the magnetic axis is reck- 
oned from the negative pole towards the positive one. 
AOnnson, tr. of Mascart and Joubert, I. 285. 
2. Pertaining to the earth's magnetism : as, the 
magnetic north; the magnetic meridian. See 
phrases below. 3. Having properties analo- 
gous to those of the magnet; attractive; win- 
ning. 
Doubtlesse there is a certaine attraction and magnetic!,' 
force betwixt the religion and the ministeriall forme 
thereof. Milton, Church-Government, i. 3. 
Magnetic axis. See m<i. Magnetic azimuth. See 
azimuth. Magnetic battery, a kind of battery formed 
of several magnets (usually horseshoe magnets) combined 
together, with all their poles similarly disposed. Also called 
a magnetic magazine or a compound magnet. Magnetic 
cohesion. See cohesion. Magnetic curves, the name 
given to those curves in which an infinite number of very 
minute needles would arrange themselves when placed 
round a magnet and at liberty to move round an axis. An 
M.iynetic Curves. 
idea of these curves is given by the appearance of iron-fil- 
ings when scattered upon a sheet of paper and agitated 
immediately above a magnet. They show the direction of 
the lines of force in the magnetic fleld that is. in the space 
about the magnet within which its action is felt. Mag- 
netic declination. See declination .Magnetic densi- 
ty, the amount of free magnetism per unit of surface. 
Magnetic dip. Sameasdipoftheneedle(vt\iicli see, under 
dip). Magnetic elements of a place. See element. 
Magnetic equator. See equator and magnet. Magnetic 
