Antiquity Of Tin And Medical Use





Moses, who was born 1600 B.C., mentions tin, and history records its use

500 B.C., but not for filling teeth; much later on, the Ph[oe]nicians

took it from Cornwall, England, to Tyre and Sidon.



The alchemistic name for tin is Jove, and in the alchemistic

nomenclature medicinal preparations made from it are called Jovial

preparations.



Hindoo native doctors give tin salts for urinary affections. Monroe,

Fothergill, and Richter claim to have expelled worms from the human

system, by administering tin filings.



Blackie, in "Lays of Highlands and Islands," referring to tin as money,

says,--



"And is this all? And have I seen the whole

Cathedral, chapel, nunnery, and graves?

'Tis scantly worth the tin, upon my soul."



"Tin-penny."--A customary duty formerly paid to the tithingmen in

England for liberty to dig in the tin-mines.



In 1846, Tin (Stannum, symbol Sn) was found in the United States only at

Jackson, N. H. Since then it has been found, to a limited extent, in

West Virginia and adjoining parts of Ohio, North Carolina, Utah, and

North Dakota. The richest tin mines of the world, however, are in

Cornwall, England, which have been worked from the time of the

Ph[oe]nician discovery.



The tin which is found in Malacca and Banca, India, is of great purity,

and is called "Straits Tin" or "Stream Tin." It occurs in alluvial

deposits in the form of small rounded grains, which are washed, stamped,

mixed with slag and scoriae, and smelted with charcoal, then run into

basins, where the upper portion, after being removed, is known as the

best refined tin. Stream tin is not pure metallic tin, but is the result

of the disintegration of granitic and other rocks which contain veins of

tinstone. Banca tin is 99.961 parts tin, 0.019 iron, 0.014 lead in 100

parts; it is sold in blocks of 40 and 120 pounds, and a bar 0.5 meter

long, 0.1 broad, 0.005 deep can be bent seventy-four times without being

broken. Subjected to friction, tin emits a characteristic odor.



Tin in solution is largely used in electro-metallurgy for plating. Pure

tin may be obtained by dissolving commercial tin in hydrochloric acid,

by which it is converted into stannous chlorid; after filtering, this

solution is evaporated to a small bulk, and treated with nitric acid,

which converts it into stannic oxid, which in turn is thoroughly washed

and dried, then heated to redness in a crucible with charcoal, producing

a button of tin which is found at the bottom of the crucible.



Pure tin may be precipitated in quadratic crystals by a slight galvanic

current excited by immersing a plate of tin in a strong solution of

stannous chlorid; water is carefully poured in so as not to disturb the

layer of tin solution; the pure metal will be deposited on the plate of

tin, at the point of junction of the water and metallic solution.



In the study of tin as a material for filling teeth, we have deemed it

expedient to consider some of its physical characteristics, in order

that what follows may be more clearly understood.



Tin possesses a crystallized structure, and can be obtained in

well-formed crystals of the tetragonal or quadratic system (form right

square prism), and on account of this crystalline structure, a bar of

tin when bent emits a creaking sound, termed the "cry of tin;" the purer

the tin the more marked the cry.



The specific gravity is 7.29; electrical state positive; fusing point

442 deg. F.; tensile strength per square inch in tons, 2 to 3. Tensile

strength is the resistance of the fibers or particles of a body to

separation, so that the amount stated is the weight or power required

to tear asunder a bar of pure tin having a cross-section of one square

inch.



Tenacity: Iron is the most tenacious of metals. To pull asunder an iron

wire 0.787 of a line in diameter requires a weight of 549 lbs. To pull

asunder a gold wire of the same size, 150 lbs.; tin wire, 34 lbs.; gold

being thus shown to be more than four times as tenacious as tin.

(Fractions omitted.)



Malleability: Pure tin may be beaten into leaves one-fortieth of a

millimeter thick, thus requiring 1020 to make an inch in thickness.

Miller states that it can be beaten into leaves .008 of a millimeter

thick, thus requiring 3175 to make an inch in thickness. Richardson says

that ordinary tin foil is about 0.001 of an inch in thickness.



If the difficulty with which a mass of gold (the most malleable of

metals) can be hammered or rolled into a thin sheet without being torn,

be taken as one, then it will be four times as difficult to manipulate

tin into thin sheets.



Ductility: If the difficulty with which gold (the most ductile of

metals) can be drawn be taken as one, then it will be seven times as

difficult to draw tin into a wire. At a temperature of 212 deg. it has

considerable ductility, and can be drawn into wire.



Among the metals, silver is the best conductor of heat. If the

conductivity of silver be taken as 100, then the conducting power of

gold would be 53.2; tin, 14.5; gold being thus shown to be nearly four

times as good a conductor of heat as tin. Among the metals, silver is

the best conductor of electricity. If its electrical conductivity be

taken at 100, then the conducting power of gold would be 77.96; tin,

12.36; gold being thus shown to be more than six times as good a

conductor of electricity as tin.



Resistance to air: If exposed to dry, pure air, tin resists any change

for a great length of time, but if exposed to air containing moisture,

carbonic acid, etc., its time resistance is reduced, although even then

it resists corrosion much better than copper or iron.



As to linear expansion, when raised from 32 deg. to 212 deg. F., aluminum

expands the most of any of the metals. Taking its expansion as 1, that

of tin would be 3, i.e., aluminum expands three times as much as tin.

(Dixon, "Vade Mecum.")



Solids generally expand equally in all directions, and on cooling return

to their original shape. Within certain limits, metals expand uniformly

in direct proportion to the increase in temperature, but the rate of

expansion varies with different metals; thus, under like conditions, tin

expands nearly twice (1-3/5) as much as gold, but the rate of

expansion for gold is nearly twice (1-7/10) that of tin.



The capacity for absorbing heat varies with each metal; that of gold is

about twice (1-3/4) that of tin.



Tin has a scale hardness of about 4, on a scale of 12 where lead is

taken as the softest and platinum the hardest. (Dixon, "Vade Mecum.")



Tin has a scale hardness of about 2. (Dr. Miller.)



To fuse a tin wire one centimeter in diameter requires a fusing current

of electricity of 405.5 amperes. Up to 225 deg. C., the rise in resistance

to the passage of an electric current is more rapid in tin than in gold.

In some minerals the current follows the trend of the crystals.



Gold wire coated with tin, and held in the flame of a Bunsen burner,

will melt like a tin wire. At 1600 deg. to 1800 deg. tin boils and may be

distilled.





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