Scientific American, Volume XXXVI., No. 8, February 24, 1877 | Page 8

prepared has been dipped in the glaze, the colors are applied on the soft
surface of the latter, and the vitrifying process fuses all into a glossy
enamel of the color of the pigment. This is still the common practice;
and we mention it merely to show that to his pigment and glaze
Andreoli must have added some third substance, which rendered the
enamel capable of reflecting white light as blue, red, green, or yellow
light--in other words, of giving the object a luster of a color wholly
different from the tints of the pigment. He evidently could produce any
desired color at will, and the effects gained are indescribably beautiful.

The Castellani collection contains 130 superb specimens, which glow
like jewels. In one, the scene of the nativity of Christ is provided with
the figures in low relief, and the exquisite cerulean lustre is imparted to
give the effect of moonlight. The rarest pieces are those of which the
luster is a delicate green. Some blaze with yellow, as if of gold; others
exhibit the brilliancy of the ruby; while others resemble the interior of
the pearl oyster shell. Whether this sheen is produced by polarization of
the light in some manner, or whether it is at all analogous to
fluorescence, is yet to be decided. The impression of the surface with
fine microscopic lines might produce an iridescence, but not separate
and clearly defined hues. The ware was intended for ornamental
purposes, not for household use; and it was suspended against the rich,
dark tapestries of the period with which walls were covered, thus aiding,
as it were, in illuminating the apartment with its exquisite radiance.
* * * * *

THE BLUE GLASS DECEPTION.
On September 26, 1871, General A.J. Pleasonton, of Philadelphia, Pa.,
obtained a patent for "utilizing the natural light of the sun transmitted
through clear glass, and the blue or electric(!) solar rays transmitted
through blue, purple, or violet colored glass, or its equivalent, in the
propagation and growth of plants and animals." In his specification, of
which the above constitutes one claim, he states that he has discovered
"special and specific efficacy in the use of this combination of the
caloric rays of the sun and the electric blue light in stimulating the
glands of the body, the nervous system generally, and the secretive
organs of man and animals." He also states that he finds that vegetation
is vastly improved by the transmitted blue light. These alleged
re-discoveries--for the General only claims to have devised the method
of utilizing them--were extensively promulgated through the press early
in 1871. Subsequently, in 1876, General Pleasonton published a book
on the subject, the volume being appropriately bound in blue and
printed in blue ink. Recently public attention has again been called to
the subject by a New York daily journal. The peculiar kind of glass in

question is known as "pot metal blue," that is, it is stained a bluish
violet throughout, and is not clear glass covered with flashings of blue
glass. It is used in greenhouses, etc., in connection with clear glass; and
in General Pleasonton's grapery it appears that only every eighth row of
panes was blue. Some of the results alleged to have been obtained by
exposing animals and plants are as follows: Twenty grape vines, in
their second year, after being set out under the blue glass, bore 1,200
lbs. of splendid fruit. A very weak Alderney bull calf was in four
months developed into a strong and vigorous bull. Heifers when kept
under blue glass may safely bear young when 18 months old. A weak
child, weighing but 3½ lbs. at birth, weighed at the end of four months
22 lbs.--the light in this instance having come through blue curtains.
Two major-generals with rheumatism were cured in three days. A
young lady whose hair had come out regained her tresses; and to these
must be added various other cures of severe ailments which we have
not space here to recapitulate. The above are the alleged facts; and we
propose to consider the supposed discovery in the light of previous
investigations.
With reference to the theories of electricity, etc., advanced by General
Pleasonton to account for his phenomena, their absurdity is so complete
that we shall waste no time over them. The important question in the
matter, and the only one in which the public is interested, is whether or
not blue glass is capable of producing all or any of the results imputed
to its use. In order to clear the way for the examination of the
investigations, the records of which we have carefully collected, let us
consider first those which General Pleasonton quotes in support of his
views. These are (1) Seunebier's researches, which go to show that the