Evening star., 1925-07-19
Light on Light.

Ultraviolet Gnvisible) light from di-
rect sunlight or from the electric arc
lamp or the mercury vapor quartz
lamp will kill bacteria and some of
the higher organisms (protozoa) in
thin layer of clear water in few
seconds; apparatus for this purpose
devised by Thresh and Bealle steril-
lied from so OF 200 gallons of water
per hour, depending on the character
of the water. Colon bacilli are killed
In Is to 20 seconds. typhoid germs in
10 to 20 seconds, cholera germs in 10
to Is seconds, some of the more re-
sistent spores in 80 to so seconds, with
a Cooper-Hewitt mercury vapor lamp
having a quartz lens instead of glass
and a current Of amperes, 130 volts.
Ultraviolet rays are the invisible
rays beyond the violet in the spectrum
or rainbow; they cause the chemical
change in the photographer 8 sensitive
plate or film and the medical or physi-
illogical changes brought about by
exposure of the living organism to
sunlight or other source of ultraviolet
energy or influence. Sunburn or tan
ming is not the only effect of exposure
of the body to sunlight. Roller has
shown the world how the ultraviolet
atmosphere occurs will cure tubercu-
losis, and before Roller introduced
the sun bath treatment at Leysin. in
the Swiss Alps, Finsen had discovered
the power of ultraviolet rays to cure
lupus (skin tuberculosis) and other
bacterial or protozoal skin diseases.
Recently our own research workers
have demonstrated by animal expert
mentation that the ultraviolet ray
has the power to protect animals and
man from the tendency to develop
ricketts, when the food is deficient in
the vitamin which prevents ricketts,.
Exposure to ultraviolet light, either
from direct sunlight or from the arc
lamp or the mercury vapor quartz
lamp, is now a well established
method Of treating ricketts, in the
earliest stage of the disease.
DIR. Alfred H. Hess, New York pedi-
artist, has found, with his co-workers
in this field. that food substances
which ordinarily carry little or none
of the essential vitamin may be made
capable of preventing ricketts, by ir-
radiation with ultraviolet light; even
vegetable oils may be rendered almost
as effective against ricketS by this
means as cod liver oil is.
Some research workers of the Great
Britain Medical Research Council re-
Gently proposed that the mysterious
quality of the open air, of fresh air,
which distinguishes pure air from
dead, foul, impure confined air, may
be a physiological potency acquired
from this activation by ultraviolet
light. We have always fancied that
the air of mountain regions has some
health-giving virtue not so noticeably
present in the air in the valleys. We
have long believed that the open air,
the outdoor air, is more healthful than
indoor air. all other physical or chemi-
cal features being equal. This sugges-
tion of the British Psychologists has
not been substantiated as yet.
DR.. John B. Todd of Syracuse. whose
introduction of the cloth window
screen method of ventilation for school
rooms and other rooms indirectly
brought about the scrapping of many
thousands of dollars worth of me-
chanical ventilation equipment in New
York schools, put forward this same
idea of possible vitamin in fresh air