Evening journal., 1897-10-16
HOW THE SKIN TANs.
Explanation of the Effects of Light
and Heat
Produced bs the same Rays That Are
Effective In PhOtogrnphy-An
Interesting and Instruc-
tive study.

often painfully, upon peoples notlce
every summer. is one in which modern
scientifc Investigations have developed
many interesting facts. Contrary to
the former popular belief that sunburn
was due to the heat of the sun, II has
now been shown thatitis the suns light
chiefly which affects the skin. That
severe sunburn may be produced with
out heat has been proved by the fact
that persons exposed 10 strong sunlight
on the tops of mountains at extremely
low temperatures have been burned
Just as II they had undergone the suns
heat as well. Alpine travellers and those
who have taken long Journeys over the
snow have had the experience of being
painflllly burned by the reflected light
from the white, glittering surface, and
eunburn from reflections on the water
is equally we'll known. That heat alone
does not produce the effects clear from
lnanv evidences. Persons exposed TO
the high temperatures which prevail in
the firerooms of ocean steamers, in deep
mines and other places, do not become
tanned and burned In the same manner
as those who work in the sun.
According to the present theory. then,
sunburn. or tan. is produced by the ac-
ainlc rays Of the suns light-fhat is,
those rays which POSSESS the power OF
affecting chemically certain substances
upon which they fall. In photography
81 is we'll known thatAhe blne or violet
rays Of light have far more effect upon
The sensitive plate than the red rays,
and recent experiments have tended to
show that this IS also true regarding
the rays and the human skin. The ex-
periments have been conducted with
differently colored glass screens, placed
between the light and the skin. Red
glass. according 10 the principles Of
physics, allows the red light rays to
pass through Il freely. while rejecting
the complementary blue rays. In the
same way. blue glass admits the blue or
violet rays and excludes the red. Thus,
as tire red rays have been shown 10 have
the least chemical power, any red sub
stance which screened the skin, allow
ing only the comparatively harmless
rays Of ihatcolor TO penetrate, would be
.she most effective protection against
sunburn.
A rather amusing but we'll authenti-
Gated instance is proof Of this. A
woman who was travelling on foot with
n party of tourists wore a waist which
had alternate broad stripes OF white
and red. After long exposure TO the
sunlight she found that she had been
burned through the material Of the
waist, and. to her utter astonishment,
that the burn was in well-marlSed
stripes-iptense under the white bars
OF cloth. and scarcely perceptible under
the red ones. (Whte, which allows all
rays to pass through it. is practically
llks no screen at all) This experience
would indicate that red wells. for in
stance, would be the best to protect the
face, and that the old-fashioned blue
wells worn few years ago were of the
most undesirable color possible.
That part OF the skin which receives
the chemical action OF the light rays so
as 20 produce sunburn, tan, or freckles
ls'the pigment, ,'or coloring matter. This
varies greatly In sensiiiveness in diff
ferent persons, not always being gov
erned by the complexion, although. as
rule, blonds and redAaired persons
are more subject 10 sunburn thar
others. just why some people burn red
while others freckle or tan, does moi
seem TO be definitely known. Doctors
usually say that the difference is du,
merely to the varying qualities of skins
Generally. after months of exposure
20 the sun. any skin becomes hardened
10 IT'S effects, takes on permanen
brown or bronze color, and is no
changed thereafter by any amount o
additional exposure. But there are eN
ccptions TO this rule. There is an OLE
fisherman down on the Great South bay
who. though he has lived in the open al
all his life, is continually being burne'
afresh by the suns rays. Year afte
year his face peels and becomes sor
several times IN a season. The ski
has never been able 10 accustom i5sel
30 the burning sunlight.
The darkening of The pigmenti in th
skim" said a a'physician, els an effort O
nature TO interpose defense ugains
the infiaming light rays. The darke
the surface upon which they fall tn
more difficult is IL for them TO pas
through and injure the sensitive part
Dtutdtns 0uuDuIus uONtNelt boSo uN
do any real harm TO the skin; in fac
the light and air are rather beneticiu
than otherwise. although the first e.
feet. II Vhere'is swelling and extrem
heat, is rather painful"
When asked why wind often SCENE
10 produce burn as readily as sunligh
the doctor said;
The wind by irritating the skin, pre-
duces a certain amount Of congestion
audthus predisposes to the effect Of IN
sunlight. When The skin is even slighi
" congested it will burn quickly, eve
In rather weak light. in The sam
way heat also, by congesting the skin
IS a predisposing cause 10 sunburl
though not the direct cause. which
10 be found in the light"
In connection with the subject Of III
effect Of light upon fhe skin it is int
esting 10 recall the many cases in whic
the Roentgen rays have caused SOM
thing almost precisely like sunbur
Persons who have exposed their hanC