The daily gazette., 1877-04-03
"BLUE LIGHT AND SUNLIGHTn

sunlight on vegetable and animal life, by
the republication Of General Pleasanton's
memoir onthe subject, has been extend
ed by the criticisms and attables upon the
authors theories. On tee one side We
have In General Pleasanton's booklvery.
many authenticated cases. which appar.
emily show remarkable development of
animal and vegetable life and vigor under
the influence of blue light associated with
sunlight, and on the other side We have
"quips. and sentences, and paper bullets
of the BRAIN" which may amuse, but
should never awe a man from the career
of his humor." And we have, moreover,
elaborate treatises based on what may be
called the accepted facts of nature, writ
ten to show that Gen. Pleasanton's the
ory as to the influence of associated blue
light and sunlight is erroneous.
In short, the doctors disagree, but, for
tunately, no one is required to decide
just yet as to the relative value of theor-1
les explaining the cause Of the phenom-
ena. The first questions must be as to
the truth of the alleged effects and the
correctness of the assumption that the
effects are caused by an association OF
rays of particular color with sunlight.
When those questions have been deter
mined beyond all oavil it will be time
enough to discuss questions of relations
between the ascertained cause and the as
certained effect.
General PleasantOn's memoir on the
subject shows that in 1861 he tried his
first experiment in cold grapery light
cd through plain and violet-colored glass
in the proportion of about seven to one.
Although violet glass was used in the
earlier experiments, General Pleasan-
ton ascribes all the effects produced un-
der 1t to the blue in the violet, and hence
lott - 4ax
There is abundant evidence to show that
the growth of the vines under the associ<
ated lights was exceptionally rapid; they
bore large crop of grapes in the second
season after planting, and continued for
nine years thereafter to bear large crops
of grapes, not becoming exhausted, as
was expected. At the end of nine years,
whom tho memoir on the subject was
written, the plants were still vigorous and
healthy. This experiment was made to
some extent comparative, as vines of the
man in an ordinary grapery did not grow
| with anything like the growth shown by
those in General Pleasanton's grapery.-
A similar experiment was tried with pigs
separated from litter, one lot being put
under the influence of violet light and
sunlight and another lot in an ordinary
piggery. The former grew much more
rapidly than tho latter, although all re-
ceived the same treatment in other re-
Ispects. Other experiments were tried,
and General Pleasanton's book contains
many letters from former invalids, who
believe that they have been cured of ner-
vous diseases and other affections by the
blue glass treatment. 1t Is unnecessary
/ to narrate these cases, as many of them
have no value as experiments, and the
two cited above are among the best of the
book. They both seem to have been sue
cessful, the one In developing vegetable
: and the other animal life, and they show
. to some extent comparative results.
Those results are of sufficient import
Ance to make it desirable that more OK
tended and more exact experiments
: sh hould be made with blue light associa.
ted with sunlight. They do not, as they
stand, demonstrate beysnd question any
fact Of moment, although they obtair
Fictitious support from a large numhel
of other experiments, few OF which arr
, as nearly conclusive while some are con
tradictory, as for instance, those which
are brought forward to show that obnox
ious insects are killed by exposure to tn,
! blue ray. Further experiments with th'
: blue glass associated with sunligh
o should show first the comparative re
E suits OF exposure Of animal and vegeta
bic life under the associated lights ant
under sunlight alone, all other con
r ditions being the same, and then, il the
t results show an advantage in favor o
! associated lights. experiments should
i be made with other colored lights an,
screens preserving in all else the sam,
r conditions. 1t is quite possible ian,
from General Plsasanton's experiment
] Int would appear to be probable) tina
{ animal and vegetable life may be stin
4 ulated ander the blue ray associates
: with sunlight; but this fact should b
settled first, and theories to explain !
g invented afterwards, else one may fal
: into the condition Of the schoolboy VIII,
j undertook to explain why fish coul'
be put into basin filed to the brir
with water without causing the water t
: overflow. In the boys case simple e1
pertinent would have shown him tha
there was no truth in the alleged fac
and hence nothing to be explained. !
this case more elaborate experiment
will be required, but they are no les
ing as to causes. Photographers hav
n used blue glass in their galleries fc
many years, and for definite purpos
They wish to shut of some of the ray
le of light (reducing its Intensity, an
y they use blue glass for the purpose. be
q cause blue, while excluding all the othe
{ rays of the spectrum, admits the pa
i sage Of the blue rays, and in the vlole
II or blue end Of the spectrum are all tn
e; chemical rays which the Photographic
= requires to make chemical changes o
: the exposed negative. For an opposit
reason he uses yellow glass for the wiz
dows OF his clark room," so as to exclud
the chemical rays while admitting igh
The photographers successful use {
glass of different colors in differer
branches of his work is based directly o
l. the accepted theory of light. and the sam
theory may possibly explain the result
obtained BY the use OF blue glass in col
- servatories, graperies and sick room
General Pleasanton has seen fit to ascrit
the effects to electrical action, but th
question Of hop the effect is produced
at present Of inferior Importance to til
. primary one, are they produced by tt
use of blue glass? At present the ev
dence, although not conclusive, is
g favor Of General Pleasanton's side I
this question, and he can afford TO star
the ridicule of small wits and attacks c
the validity of his theory on the subjec
lie the utility of blue glass in developer