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Sinclair Tousey.

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MEDICAL ELECTRICITY
RONTGEN RAYS
AND RADIUM

WITH A PRACTICAL CHAPTER ON PHOTOTHERAPY



BY

SINCLAIR TOUSEY, A. M., M. D.

CONSULTING SURGKON TO ST. BARTHOLOMEW'S CLINIC. NI-.W YORK. CITY



THIRD EDITION, THOROUGHLY
REVISED AND GREATLY ENLARGED



CONTAINING X fi 1 PRACTICAL
ILLUSTRATIONS, 16 IN COLORS



W. B. SAUNDERS COMPANY

1921



DEDICATED
TO MY FATHER,

JOHN EUART TOUSEY.



PREFACE TO THE THIRD EDITION



MOST important advances have been made in dental and gastro-
intestinal radiography and in the standardization of apparatus and
technic. The latter has made possible tables showing the correct
exposure for radiographs of every portion of both sexes and of every
weight and measurement. The saving in time and the certainty of
good results have been obtained by many hundred hours' work in
studying the methods and results in thousands of radiographs. The
rehabilitation of those suffering from the results of war injuries is
.mother important subject.

Then 1 are described in this book inventions, patented and unpat-
ented, and it is not to be assumed because patents are not specifically
mentioned in connection with the various descriptions that there are
no patents or that the rights are not protected.

SINCLAIR TorsKY.

\F.\S YOKK CITY, .1 /</'</, 1921.

9



PREFACE



Now that the work approaches completion the author realizes that
it is impossible for any book on electricity to be up to date. A weeklv
magazine would be more apt to justify this title in the case of a science
which is developing so rapidly and along such important lines. A
systematic attempt to present what has been done and of how to do it
may. however, prove useful. Where a statement is ascribed to some
particular observer, this is done either because the statement has not yet
been verified by universal experience or in order to give; due credit to
the discoverer of an established fact. The radiographs in this book
were made by the author except where otherwise stated, and the tech-
nic employed is one available for the average practitioner who desires
uniformly successful results. Lightning speed is attainable by the dis-
tinguished expert, but sometimes at a ruinous expense for j-ray tubes.
The author's frequent use of the name " .r-ray " is perhaps excusable on
the ground that it is the name Rontgen gave to the form of radiation
which he discovered. The author acknowledges, with thanks, his in-
debtedness to Dr. Smith Mly Jelliffe and Dr. Harry F. Waite for their
assistance; and to his assistants at St. Bartholomew's Clinic and to
other gentlemen to whom due credit is given for radiographs made by
them. The authors consulted are mentioned at the respective parts of
the book, but special mention should be made here of the works of
Houston, ,J.J. Thomson, Curie, Albert-Weil, and Bordier, The author's
greatest obligation is, of course, to the professional friends who have
n-fenvd patients to him.

SINCLAIR TOIASKY.



CONTENTS



PAGE

(IE.NEKAL CONSIDERATIONS ...... 17

STATIC ELECTRICITY ................ _>.",

Insulators and Conductors ..... L'.~i

The Leyden Jar ............... '_''>

Nature of Electric Sparks ............ L'7

The Modern Static or Influence Machines. . :',()

Sonic Practical Electric I'nits ........ Is

Sources of Hiffli Electromotive Eorce or Static Elect ricitv . . . ">-l

The Physical Effects of Static Electricity. . ">.">

Met hods of Therapeut ic Application of Static Klectricitv . "/)

The Dosage of Static Electricity ..... 70

Physiologic and Therapeutic Effects of Static Electricity ............ 71

DYNAMIC EI.KCTIUCITY .......................... ............... 7S

Nature of Dynamic Electricity ............. ........ 7s

Sources of Dynamic Elect rcity .............. ......... N2

The Voltaic or C,alv;"i,c Cell ........................ . . S'J

Thermo-electricity ...................... ( .i7

Storage Batteries or Accumulators. '.!>

The Production of Electricity l>y Electromagnetic Induction Idti

The Dynamo .......................... ll'.'l

The Induction of Dynamic Electricity by Electric ('mi'eni<. 1^>'_'

The Character of the Alternating Elect ric-hirht ('uri'ent liil

Detection and Measurement of Electric ('urrent< ..... Itil)

Elect roma^netic ( lalvanometers . . 17.'1

The- Measurement of Electromotive |-'orce I'.tl

Regulation of Electric ( urrents ...... '_'u|

Measui'ements of Resistance ...................

Electrolysis ................................... '-Ms

The Thermal Effect of the Electric Current 'Jii'J

L'HS
Us 12

l*Sli

PHYSIOLOGIC EFKF.("I\S OK I'j.K.c'nucrrv ............ '-".>-

Physiolouic Effects of Electricity upon Microorganisms 'J!'_'

Physiologic EtVects upon \'ertelirate Animal- '_' M .i
The Effect of Elect ricity upon Anim:d Tissu




Muscular ( 'out ract ion Result inii from l'!lect ric Stimulation
The Myoiiraph ...........................

The Elect rocardiofifaph .....................

Reactions to Electric Stimulation in NYuromiisciilar Preparation
( '( >rt ical St imula I ion ........

St imulalioii of t he < V rebel la r Peduncle< .
Electric Stimulation of the Spinal * 'ol'd
Rellex Stimulation bv Elecii'icitv .



KI.KC i 'in ii)i:s . . .

Materials for Electrodes

Elect rode.- for Sui face Applicat ion
Elect rode- for < ialvaiiopimet lire



11 CO NT K NTS

PACE

Ki.K.tTKoDi \<;NOSIS 38t

Progno-i< Ba-ed on Klect rodiagnosis . ... . ... 397

IONIC M K.DIC \rioN in KI.KCTKOI.YSIS. . 399

K\A.M1'I.KS OK CiAI.VANlC, KAKADIC. A N IP Si N I 'Mil 1) \ I. Kl.lX I KoTH K If \ I' Y 422

1 1 vdro-electric Baths ... 43(1

O/one 44X

Pm>l< \I. 111. i O.NSTHl i TIOV AlTKK \\ AH IN.ITHIKS . . . 4A1

I'm - 1< il. i H, 1C AND III KKAI'IH Tir KlTKtTS ol Kl.KCTKOM A(iNKTS 4A3

Ki.KrnuriTY IN DI>I:\>F.S OK TIIK Ni-:uvor> SYSTKM 4AA

Diagnosis of Disorders of the Peripheral Nervous System. . .... 4AA

Disease of the Peripheral Sensory Nerves 470

Diagnosis and Treatment of Disease.- of Peripheral Motor Nerves

and Motor Centers . . 470

Klect roinechaiiot herapy 4X3

Practical Kxamples of the I'se of Condensers in Electrotherapeutics. . . 49A

In Connection uith the Static Klectric Machine 49A

In Connection with Induction-coils A01

Neuralgia and Neuritis A01

Kli'd i icily in Treatment of Organic Diseases of the Central Nervous

System All

Spinal ( 'ord Al 1

Brain Alti

(ieneral Nervous Disorders AH)

Neurasthenia A22

Klectric Sleep and Klectric Death A2X

Physiologic Causes of Death liy Klectricity A34

I Inai-KKi-x^rKNcv CTHKKNTS A3X

The ( Midin Pu-onator . A4X

Tesl :t High-frequency Current . . AAO

Methods <>f Applying High-frequency Currents . AA2

\acuum Klect rodes \\ith Insulated Stems AAS

* M her Applications \\ith Kt'tects Hesemhling Tho-e of High-frequency

The Physiologic Kl't'ects of High-frequency Currents A(iX

The I'iH'ect- oi ( ieneral Applications of High-l reqiiency ( 'urrents A74

Dial hi-rm\ or Theinioj tenet rat ii in (131

I'HKNoMKNV ACCOMI'ANYINC '1111. Tl{ A NSM IIO.N oK Kl ,K( 'TUK 'I 1 1 TllKotiiH

(i \sr.s (142

Imiixatioii of ( iases (142

The Pa - a ne of KlectriciU Through a Vacuum M~>

I'HO 10 i ni.it \i"i . tlAA

Principles of Phi plot herapy . . (17(1

l-Aample- of the Therapeutic I < of Klecinc Arc Light lixs

'i HI-. / - 1; \ i (W2

Piopi-i i ies of t he ./-Hay (1(14

I he I 'rod i irt ion of t he .c-Ka\ in a ( las-filled Tube, tl()(l

I i in i is of I .led I lc ( ieliel al ols Adapted to K\cit Ilig all .1 -IJaV Til lie 7 1 A

IJeuulat ion of i he PrimaiA ('urrent 72(1

'I he Type of Tlllie .....'... 7AX

iial\ l,'a\- 7(U

I'd - \uf hoi 's '( '..niacl I )iaphrat:m . XO I

Tin Si-n-ll|\-eness of the l-'illll. Plate, 0] P:ipel XOX

I : . : x2( i

1 .01 ah/atloli of l-'oreign Bodies. XI H

DP \ i-|i ipmeiit i if r-l{a\ Pict ii res X70

I lii nd Padiouraph\ of Special Part- \ the Bmlv X(lA

Th. Hi H (102

T.-chnic I'm I )ental Padiom-a]hy OMO

'I h,- \i ck )XX



CONTKNTS

THK .r-llAv: Fluroseopy ;i.iid Radiography of Special Parts of the Body

The Chest ... '.I'.Ki
.r-Ray Diagnosis of Karly I'liltnoiiary Tuberculosis . Hill

Radiography of I lie Thorax in Pneumonia Hll I

Bronchieclasis H)|.~>

Foreign Bodies in tin- Ijing. Hll.'i

The Lung Reflex . lOir,

Radioscopy of the Ksophagus. Htltl

Radiography of tin- Spine 10ir>

The Abdomen and Pelvis 1(117

The Stomach and Intestines 1021

The Author's Technie for (last ro-mtest inal Radiography. . 10^.">

rrinary Calculi 104S

Hydronephrosis 10(>2

E'yelography KM).".

Perinephritis Hlli.'J

Hemorrhagic Nephritis Hit):!

Renal Tuberculosis 1(1(11

Radiography of Yosical Calculus. 1(101

Prostatie Calculi HHif)

Foreign Bodies in the Pelvic Organs. HMK1

The Pelvic Bones 1(1(1(1

The Hip-joint ions

The Thigh 1071

Radioscopy of the Knee 1072

Radiography of Bo\v-legs . H)7."

Radioscopy of the Leg K>7"i

Fluoroscopy and Radiography of the Foot . loso

The t'pper Extremity Hixii

Radioscopy in Diseases of the Bones and .Joints 110.1

Radiography in Tumors of the Bones and Joints 1 10.")

Acromegaly 1 Hiti

Bony Changes Shown by Radiographs of Castrated Animals 1107

Osteomyelitis and Necrosis . 1107

Acute or Chronic Periostitis 110X

A Cast- of Obscure Disease of the Shoulder. . 1 10X

Syphilis of the Bones. 1 1 HI

Syphilitic Inflammation of the Bones fNon-gimunalous 111:1

Bone Syphilis in Animals . 1111

Rickets

The Joints in Rheumatism 111")

The Joints in ( lout .111(1

The Joints in Rheumatoid Arthritis or Rheumatic (lout . 1117

Hypertrophic Arthritis or Ost co-arthritis 1117

Charcot's Joint The Tabetic Joint . . 11 IX
(lonorrheal Arthritis. .
Tuberculosis of Bones and Joints.
Kxamples of the Value of 1 he .r-Ray in the
Anatomic Age Determined by Radiology.

Detection of Pearls in Oysters '. . . 11-0

Physiologic Effects of the .r-Rays 1 i:',0

From Mild Applications

.r-Ray Burns or Rontgen Dermatitis. . . 1112

Precautions Against .r-Hay Injuries. ... 111.)

Ri >vn ,i:\i >TM MtAi'Y

The Treatment of Disease by the .r-Ray

The Technic of Rontgen Therapy

The .r-Ray in the Treatment of Malignant Di.-easc
.r-Ray Treatment in Particular Diseases

Skin Diseases ...

.r-Ray Therapy in Tuberculosis .

Arthritis Deformans . . .

Trachoma

Radiotherapy in Syriimomvelia

Old Sprains.' '. .' . . .1101



II) ('ONTKNTS

PAGE

RoNTdKMiTHKKAPv: .c-Ray Treat men I in Particular Diseases

Diseased Tonsils 1192

Locomotor Ataxia 1 P>2

.r-Ray Treatment of Facial Neuralgia 1192
./-Ray Applications Alter Nerve Resection for Tic Douloureux , 119:3

Prostatic Hypertrophy . 1 191

./-Ray Treatment of ( loiter 1 P. Mi

Pernicious Anemia . . 1 19(1

Hodgkin's Disease and Pseudoleukemia and L\ mphosarcoina 1 PtS

I'olycyt hernia 1199

./-Hay Treatment of Leukemia . 1200

Kpithelioma 1200

Radio! herapy with the Tube in Direct ( 'on tact wit h t he Body 1217

Technic of Direct Applications 121S

( 'arcinoma . .... 1220

( 'arcinoma of the Breast .... 1222

Recurrent ('arcinoma of the Larynx 1227

( 'anccr of the Tongue 1229

( 'ancer of the Shoulder 1229

Secondary ('arcinoma of the Mediastinum 1229

( 'arcinoma of Stomach and Intestines 1220

( 'arcinoma of the I" ten is 12.'30

Sarcoma . 12:31

Treatment of an Inoperable Primary or Recurrent Sarcoma .

Melanosarcoma

Multiple Pigmented Sarcoma

Fluorescent Medicines in Connection with ./'-Ray Therapy. . 12:3")
Nature of the Radiance from Fluorescent Substances . 12:3(1
Influence of the Injection of Photodynamic Substances into the

Tissues before .r-Hay Kxposures 12:3S

Radiotherapy in Infectious Diseases . 12oX

Specific Immunity . 12oX

I! (Int gen Applications for Producing Sterility 12oX

R \mr\t . . 12:39

Radio-activity 12:39

Origin and Cost of Radium 12 IS

Variations in the Radio-activity of Radium 1219

Chemic KfTects of Radium Rays. . 12.").")

Radiographic Kffects of Hadium Hays 12f>(i

The Theorv of Radio-activity 12">7

Physiologic KfTects ,,f Hadium. . '. . 1LT.7

FtTects on Microorganisms 12">x

Kffect on Plants 12(10

KfTcct on Toxins 12(10

Kffect of Radium upon Animal- 12(10

KfTect of Radium upon the Kve 12(11
KfTcct upon Animals During the Stage of Development and ( >n>\\ th. 12(12

Pathologic Kffects of Radium 12(12

Thi rapeutic 1'ses of Radium . 12(>:>

\pparatu< for Therapeutic I se of Radium 12(1:!

The Dosage of Radium Radiation 12H.">

Radium Therapy 12(19

Hadium in the Treatment of Lupus 12(19

Radium in t he Treat men) of Skin Diseases 12(19

M ilignanl Disease 1271

Ha 1 1 in m Puncture for ( 'arcinoma 1 27(1
Therapeutic ("sc of Normal Saline Solution K \posrd for T\\ o \Veek-

to ilie Radiation from Radium 1277

Radium in Kve Di-ea-e- 1277

Radium in I 'terine I'ibroids 1 277

Radium in N'er\-oii- Diseases 127X

Tonic l.ttirt Tpon the Heart 127X

Substitutes for Radium 127X

. 12X1



MEDICAL ELECTRICITY AND RONTGEN RAYS



GENERAL CONSIDERATIONS

MKDIOAL electricity, or electro-therapeutics, treats of the applica-
tion of electricity to the diagnosis and treatment of disease.

Electricity is known to us through the effects produced when an
electric charge, electromotive force, or potential is developed, just
as the attraction of gravitation is known to us through the effects pro-
duced when a body is raised from the ground. Hodies in which an
electromotive force or potential or electric charge has been produced
are no longer in a state of repose, but tend to produce a variety of
effects, one of the simplest and most direct of which is losing their
electricity to some other body or to the earth, or. in other words,
becoming discharged. Many other effects are produced by the electro-
motive force in seeking a state of equilibrium heat, light, the .''-ray,
mechanic motion, chemic changes, physiologic effects. Practically,
every one of the effects produced by electric discharges is used in
electro therapeutics; and some recapitulation of our knowledge of
electric science is necessary to the proper presentation of the special
methods of producing and applying electricity in medicine.

ELECTRICITY

Electricity is sometimes regarded as a substance consisting of ex-
ceedingly minute negatively charged particles, called electrons, which
are a very great deal smaller than atoms in which they normally are
in a state of equilibrium, with a positive charge which is inseparable from
the atom. And when by the application of various chemical and
physical forces the state of equilibrium of the electrons is disturbed
there are various manifestations of [lower, such a> attraction, repulsion,
heal, light, electromagnetic induction, and chemical dissociation or
elect rolysis.

The electron- are the same regardless of the nature of tin 1 atom-
in which they are found. The underlying fact in the case of a cur-
rent of electricity i> a flow of electron - from the negative pole of the
battery or oilier generator through the external circuit to the positive
pole. If thi< tact had been known ui the I >eginning this would have
been called the direction of the cuiretit instead of the reverse. h H
an untoriunale misnomer, but doe- not make much practical
exc< |)t in considering the pa age of electricity through a vactmii



1^ MKOICAL KI.KCTHICirV AM) UOXT(;EX KAYS

like ill- 1 ("onlid^e .r-r:iy tube. There the electrons travel from the
negative terminal, and by their impact upon a target u'ive rise to vibra-
tion railed the .r-ruy. and also heat up the target, frequently to in-
camle-cence. And it seems ridiculous to call the contrary- "the direc-
tion < if tin- curn-nt ."

Th>- various familiar means of "generating electricity" are means
of freeing the electron- and applying force to them, which they, in turn,
exert in 1 heir peculiar manner.

Accepting the time honored classification of positive and negative,
the electron- are negative particles of electricity: a neirat ively charged
body contain- an excess of fi-ee electrons and a positively charged
body contains le-s than its normal quota.

"There are t\vo kind- of electricity, positive and negative. Each
ordinary atom contains a number of electrons which are always negative,
and enough ]>o-it ive electricity to exactly balance the negative electricity
of the electron-. At present it appears that the positive electricity
never leaves the atom, while the electrons allow themselves to be taken
away or added to with relative case 1 ." !

An electron i- about rrriMVi the volume of an atom, but it is so

much denser than an atom that its weight is ._,, ,',,,, that of a hydrogen
atom. I' i- sup]>osed to be -pheric in shape.

A charge of electricity is either a surplus of elect n ms. which is a nega-
tive charge, or a ileticit of electrons, which results in a positive charge.

A current <>i electricity is a movement, transfer, or passage of elec-
tron- from one place to another, either free or in negatively or positively
chartrei 1 at< 'in- < >r i< ins.

Electricity manifests itself in three principal forms, covered by the
name- of .-!. '''<, and fnr/nlic electricity. Static electricity is
;. at re-t , : n tending to a sudden discharge and resumption
of eiertric equilibrium. Voltaic electricity is electricity flowinir or
_ Ho\\ in a current. Earadic electrii'ity is a deri\"ed form of
ci;rreni electricity ;n \\hich there are rapid alternations of direction
a- applied in medicine, almo-t always relatively hiii'h ten-ion.
There are -everal tiioi lificat ions of the-e which may be produced by
-ui?:ii in-es, and ainoiiu- them are I.eyden jar di-charnc- and

-fi'eijuency current. Then, again, the secondary
: '. liiiht. the .r-ray, and other radiations and
luable application- in many different condi-

i 't tricity ilo\vn to about a century au'o was the
Thales. one of the seven wi.-e men of
' -' to i -ail at tent i. >n to the fact t hat a piece of amber
a! t raci ;;^i.i limlio. This wa.- in liOO B. c.. but no
' 'hed to the fact . About :>00 n. < . Theo-
ob-ervation thai lynthuricum pi - obalil>" our
-anie property. This i- all the pn-iii-e-s
ric scieiicr il< ,wn to the time of 1 )r. ' iillieil .



1!)

physician to Queen Kh/.abeth, in 1 (>()(). His investigations showed
that many substances possessed this properly, and tho-e in which it
could readily be produced he termed "electrics," from the ('.reek
electron, amber. Among "electrics" art; amber, sealing-wax, glass,
the diamond, hard rubber, sulphur, resin. Any of these, when rubbed
with silk or fur, become- electrified, and exhibits at once; t IK; pro pert ie>
of attracting light bodies which are not charged with electricity, or
which are charged with electricity of the opposite sign, + or (posi-
tive or negative), as the case; may be; of repelling bodies charged with
electricity of the same sign; of inducing an ele:ctric e-harge; in neighbor-
ing bodies by a pn>cess which may be like-tied to an attraction of the;
opposite electricity in the other body, and a repulsion of the; electricity
of the same sign; and of giving sparks or discharging the whole; or a
part of its electric charge to other bodies brought near enough to it.
These 1 sparks are accompanied by sound and a smell of o/one, and
sensation and perhaps reflex muscular contraction if applied to the
human body. A fine examples of the- production of electricity by
friction is obtained when one walks over a woolen carpet, shuffling
his feet, and producing a spark sufficient to light the gas or to give
quite a smart sensation if applied to a person.

" Anelectl'ics " is the name give-n by ( iilbert to t he; metals and < it her
substances in which he- was unable; to excite an electric charge by
friction. We know now t hat the reason was t hat these bodies are- good
conductors of electricity, and that the charge was carried away as
soon as it was produced. A me-tal or any other good conductor may
be charged with electricity by friction, provided it is insulated.

But all substances are 1 not equally charged, and they are' not all
charged with electricity of the same sign or polarity. Those which
would be covered by Gilbert's name', "electrics."' dove-lop the greatest
amount of electricity when rubbe-d. and among them the modern
hard rubber is perhaps the most active.

From the start, it. was ne>ted that glass rubbed with silk, and resin
rubbed with cat's fur, became- differently charged and attracted each
other, while two electrified pieces of gla - repelled each other, as did
two electrified pieces of resin. To these two different form- ot elec-
tricity the 1 te-rms vitreous and rcxinoitx were! applied. l.ate-r. when
it was found that they we're- complementary, and that two equal
e-harge-s neutralized each other, the- vitreous ele-ctricity was called
positive, and given the sign plus, while the- resinous electricity was
called negative, and given the sign minus There i< no special reason
why either one should be called positive. The mimes might jusl as
well have- been reversed. \\hen two dissimilar bodies are rubbed
together, one- becomes charged with positive and the oilier with nega-
tive- elect rich v On the two-fluid theory, friction separated the posi-
tive and negative fluids, and an excess of one fluid remained in one
body, while an excess of the 1 other was formed in the other body. { hi
the; one-fluid the'ory an excess of eh'ct
which becomes positively charged, am
body which becomes negatively chargei
Ironic theorv of electricity will be pro-
transmission of electricity through ga-

!,




20



MKIHt At. KI.Kl TKHITY AXO R(")N'T<iK\ KAYS



in the li-t hoc< imcs po-iti vely charged, and the one later in the list be-
come- negatively charged : Fur. wool ; ivory, glass; cotton, silk : the hand.
\vood; -ealinu'-wax, shellac: resin, metal-: sulphur. India-rubber: gutta-
percha. celluloii I.

The attraction of an elect rifled body for other bodies is illustrated
by tin- motion of a pith-ball suspended near an electrified body, such
as ' lu> prime conductor of a static machine. The pit h -ball immediately
swings over in contact with the prime conductor, and as soon as it
touches it i> auiain repelled. According to our diagram (Fig. I), the
positive electricity in the prime conductor attracts the negative elec-
tricity in the pith-ball and repel- its positive electricity. \Yhen The
piti.-ba'.l come- in contact with the prime conductor, it- negative
charge enter- into the prime conductor and neutralizes a portion of
1 he positive charge therein. The pith-ball, being then entirely charged



it po>itive electricity, is repelled by the prime conductor. In

Fi<r. - the [lith-ball i- represented as being suspended between the

prime c - '"..rued with electricity. It then swings

.- ' > r lately to one ;. : : c other, becoming charge' I at t he first contact

with i" -hive elect ri it . and then being attracted by the negative

pi i. where it loses its positive charge, and. acquiring a negative

repelled bv the negative pole ami attracted by t lie

; ;ive. 'I ' -; : te rep tlsimi of two similarly chai'ged bodies forms

t he ' i' 1 he iti-1 r'lliient callei ! 1 he elect n isci ipe.

The electroscope Fin. > consists of a glass case in which a bra - rod
terminate- below m two pieces of old-!caf. and above in a brass knob.
Un britiii'iiig the brass knob near a positively charged body, negative



i- a< t r.n-i < i i po-itive charge being re-

Ipoii become \
11 i- neiuhbi irh<

::<-t her. I .lit if the <_da -

, ' . in : pririn cotiducli it 1 , c >r had recei\ ei i a

iiild liave 1 ieci niie pi .-'i! i\ . -\y

} ; \ < remained divi -r^, sit

:i : u- i-eli lo-l 1 vil h -ollie coin lllcl iii- -lib-



21



In \YulCfs electroscope 1 the u'old-leave- are replaced by two quint/
filaments coated with platinum. The filaments are fa-tened t ( > ,-i
conducting rod at the top. and are al.-o joined together at the bottom,
where there is a light weight, pi oducing a uniform tension. An
electric charge causes the filaments to div< Tge most widely at their
middle (joints (Fig. \ > . The amount of thi- divergence i- observed
by a microscope magnifying 70 time.-. The objective of thi- micro-
scope is of low, and the eye-piece of hiidi. power. In this wav the
objective may be at a convenient distance from the filament-.

Another example of the repulsion between bodies charged with the
same polarity is seen when one's hair - land- on end under treatment
by static electricity. The discharge of static electricity produce- ;i



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