Scientific American Supplement, No. 497, July 11, 1885

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The hereinbefore described substance may be ground with oil and used
like ordinary paint; or it may be ground with any suitable varnish or be
mixed in the manner of water colors; or it may be employed in any other
suitable and well-known manner in which paints are employed.

My improved luminous substance is adapted for a great variety of
uses--for instance, for painting business and other signs, guide boards,
clock and watch dials, for making the numbers on houses and railway
cars, and for painting all surfaces which are exposed periodically to
direct or indirect light and desired to be easily seen during the night.

When applied with oil or varnish, my improved luminous substance can
be exposed to the weather in the same manner as ordinary paint without
suffering any diminution of its luminous property. I claim as my
invention the herein described luminous substance, consisting of
calcined chalk, sulphur, and bismuth, substantially as set forth.

Merrill B. Sherwood, Jr., of Buffalo, N. Y., obtained a patent for a
phosphorescent composition, dated August 9, 1881.

The author says: My invention relates to an improvement in
phosphorescent illuminants.

I have taken advantage of the peculiar property which obtains in many
bodies of absorbing light during the day and emitting it during the
night time.

The object of my invention is the preparation by a prescribed formula,
to be hereinafter given, of a composition embodying one of the
well-known phosphorescent substances above referred to, which will be
applicable to many practical uses.

With this end in view my invention consists in a phosphorescent
composition in which the chief illuminating element is monosulphide of
calcium.

The composition obtained by the formula may be used either in a powdered
condition by dusting it over articles previously coated, in whole or in
part, with an adhesive substance, or it may be intimately mixed with
paints, inks, or varnishes, serving as vehicles for its application, and
in this way be applied to bodies to render them luminous.

The formula for obtaining the composition is as follows: To one hundred
parts of unslaked lime, that obtained from calcined oyster shells
producing the best results, add five parts of carbonate of magnesia and
five parts of ground silex. Introduce these elements into a graphite or
fire-clay crucible containing forty parts of sulphur and twenty-five
parts of charcoal, raise the whole mass nearly or quite to a white heat,
remove from the fire, allow it to cool slowly, and, when it is cold or
sufficiently lowered in temperature to be conveniently handled,
remove it from the crucible and grind it. The method of reducing the
composition will depend upon the mode of its use. If it is to be applied
as a loose powder by the dusting process, it should be simply ground
dry; but if it is to be mixed with paint or other similar substance,
it should be ground with linseed or other suitable oil. In heating the
elements aforesaid, certain chemical combinations will have taken place,
and monosulphide of calcium, combined with carbonate of lime, magnesia,
and silex, will be the result of such ignition.

If, in the firing of the elements, as above set forth, all of the
charcoal does not unite with the other elements, such uncombined portion
should be removed from the fused mass before it is ground.

If it is designed to mix the composition with paints, those composed of
zinc-white and baryta should be chosen in preference to those composed
of white lead and colored by vegetable matter, as chemical action will
take place between the composition and paint last mentioned, and
its color will be destroyed or changed by the gradual action of the
sulphureted hydrogen produced. However, by the addition of a weak
solution of gum in alcohol or other suitable sizing to the composition,
it may be used with paints containing elements sensitive to sulphureted
hydrogen without danger of decomposing them and destroying their color.

In many, and possibly in a majority of cases, the illuminating
composition applied as a dry powder will give the most satisfactory
results, in view of the tendency to chemical action between the paint
and composition when intimately mixed; in view of the fact that by
the addition to paint of any color of a sufficient quantity of the
composition to render the product luminous, the original color of the
paint will be modified or destroyed; and, also, in view of the fact that
the illuminating composition is so greatly in excess of the paint, the
proportions in which they are united being substantially ten parts
of the former to one of the latter, it will be difficult to impart a
particular color to the product of the union without detracting from
its luminosity. On the other hand, the union of dry powder with a body
already painted by the simple force of adhesion does not establish
a sufficiently intimate relation between it and the paint to cause
chemical action, the application of a light coat of powder does not
materially change the color of the article to which it is applied; and,
further, by the use of the powder in an uncombined state its greatest
illuminating effects are obtained. Again, if the appearance in the
daytime of the article which it is desired to have appear luminous at
night is not material, it may be left unpainted and simply sized to
retain the powder.

In printing it is probable that the composition will be employed almost
exclusively in the form of dry powder, as printing-ink, normally pasty,
becomes too thick to be well handled when it is combined with powder in
sufficient quantity to render the printed surface luminous. However, the
printed surface of a freshly printed sheet may be rendered luminous by
dusting the sheet with powder, which will adhere to all of the inked and
may be easily shaken from the unmoistened surfaces thereof.

I am aware that monosulphide of calcium and magnesia have before
been used together in phosphorescent compounds. What I claim is a
phosphorescent composition consisting of monosulphide of calcium,
combined with carbonate of lime, magnesia, and silex, substantially as
described.

Orlando Thowless, of Newark, N.J., obtained a patent for a process of
manufacturing phosphorescent substances dated November 8, 1881.
The inventor says: The object of my invention is to manufacture
phosphorescent materials of intense luminosity at low cost and little
loss of materials.

I first take clam shells and, after cleaning, place them in a solution
composed of about one part of commercial nitric acid and three parts of
water, in which the shells are allowed to remain about twenty minutes.
The shells are then to be well rinsed in water, placed in a crucible,
and heated to a red heat for about four hours. They are then removed and
placed, while still red-hot, in a saturated solution of sea salt, from
which they are immediately removed and dried. After this treatment and
exposure to light the shells will have a blood-red luminous appearance
in the dark. The shells thus prepared are used with sulphur and
the phosphide and sulphide of calcium to produce a phosphorescent
composition, as follows: One hundred parts, by weight, of the shells,
prepared as above, are intimately mixed with twenty parts, by weight, of
sulphur. This mixture is placed in a crucible or retort and heated to a
white heat for four or five hours, when it is to be removed and forty
parts more of sulphur, one and one-half parts of calcium phosphide, and
one-half part of chemically pure sulphide of calcium added. The mixture
is then heated for about ninety minutes to an extreme white heat. When
cold, and after exposure to light, this mixture will become luminous.
Instead of these two ignitions, the same object may be in a measure
accomplished by the addition of the full amount of sulphur with the
phosphide and sulphide of calcium and raising it to a white heat but
once. The calcium phosphide is prepared by igniting phosphorus in
connection with newly slaked lime made chemically pure by calcination.
The condition of the shells when the sulphur is added is not material;
but the heat renders them porous and without moisture, so that they will
absorb the salt to as great an extent as possible. Where calcined shells
are mixed with solid salt, the absorbing power of the shells is greatly
diminished by the necessary exposure, and there will be a lack of
uniformity in the saturation. On the contrary, by plunging the red-hot
shells in the saline solution the greatest uniformity is attained.

Instead of using clam shells as the base of my improved composition, I
may use other forms of sea shells--such as oyster shells, etc.

I claim as new:

1. The herein described process of manufacturing phosphorescent
materials, which consists in heating sea shells red-hot, treating them
while heated with a bath of brine, then, after removal from the bath,
mixing sulphur and phosphide and sulphide of calcium therewith, and
finally subjecting the mixture to a white heat, substantially as and for
the purpose described.

2. The described process, which consists in placing clean and red-hot
clam shells in a saturated solution of sea salt, and then drying them,
for the purpose specified.

* * * * *

BOXWOOD AND ITS SUBSTITUTES.

[Footnote: Prize essay written for the International Forestry
Exhibition, Edinburgh.]

By JOHN R. JACKSON. A.L.S., Curator of the Museums, Royal Gardens, Ken.

The importance of the discovery of a hard, compact, and even grained
wood, having all the characteristics of boxwood, and for which it would
form an efficient substitute, cannot be overestimated; and if such
a discovery should be one of the results of the present Forestry
Exhibition, one of its aims will have been fulfilled.

For several years past the gradual diminution in the supplies of
boxwood, and the deterioration in its quality, have occupied the
attention of hardwood merchants, of engravers, and of scientific men.

Of merchants, because of the difficulties in obtaining supplies to meet
the ever increasing demand; of engravers, because of the higher prices
asked for the wood, and the difficulty of securing wood of good size and
firm texture, so that the artistic excellence of the engraving might be
maintained; and of the man of science, who was specially interested
in the preservation of the indigenous boxwood forests, and in the
utilization of other woods, natives, it might be, of far distant
countries, whose adaptation would open not only a new source of revenue,
but would also be the means of relieving the strain upon existing
boxwood forests.

While by far the most important use of boxwood is for engraving
purposes, it must be borne in mind that the wood is also applied to
numerous other uses, such, for instance, as weaving shuttles, for
mathematical instruments, turnery purposes, carving, and for various
ornamental articles, as well as for inlaying in cabinet work. The
question, therefore, of finding suitable substitutes for boxwood divides
itself into two branches, first, directly for engraving purposes, and,
secondly, to supply its place for the other uses to which it is now put.
This, to a certain extent, might set free some of the boxwood so used,
and leave it available for the higher purposes of art. At the same time,
it must not be forgotten that much of the wood used for general purposes
is unsuited for engraving, and can only therefore be used by the turner
or cabinet maker. Nevertheless, the application of woods other than box
for purposes for which that wood is now used would tend to lessen the
demand for box, and thus might have an effect in lowering the price.

So far back as 1875 a real uneasiness began to be felt as to the future
supplies of box. In the _Gardeners' Chronicle_ for September 25, of that
year, page 398, it is said that the boxwood forests of Mingrelia in the
Caucasian range were almost exhausted. Old forests, long abandoned, were
even then explored in search of trees that might have escaped the notice
of former proprietors, and wood that was rejected by them was, in 1875,
eagerly purchased at high prices for England. The export of wood was at
that time prohibited from Abhasia and all the government forests in
the Caucasus. A report, dated at about the same period from Trebizond,
points out that the Porte had prohibited the cutting of boxwood in the
crown forests. (_Gardeners' Chronicle_, Aug. 19, 1876, p. 239.) Later
on, the British Consul at Tiflis says: "_Bona fide_ Caucasian boxwood
may be said to be commercially non-existent, almost every marketable
tree having been exported." (_Gardeners' Chronicle_, Dec. 6, 1879, p.
726.)

The characters of boxwood are so marked and so distinct from those of
most other woods that some extracts from a report of Messrs. J. Gardner
& Sons, of London and Liverpool, addressed to the Inspector-General of
Forests in India, bearing on this subject, will not be without value;
indeed, its more general circulation than its reprint in Mr. J.S.
Gamble's "Manual of Indian Timbers" will, it is hoped, be the means of
directing attention to this very important matter, and by pointing
out the characters that make boxwood so valuable, may be the means of
directing observation to the detection of similar characters in other
woods. Messrs. Gardner say:

"The most suitable texture of wood will be found growing upon the sides
of mountains. If grown in the plains the growth is usually too quick,
and consequently the grain is too coarse, the wood of best texture being
of slow growth, and very fine in the grain.

"It should be cut down in the winter, and, if possible, stored at once
in airy wooden sheds well protected from sun and rain, and not to have
too much air through the sides of the sheds, more especially for the
wood under four inches diameter.

"The boxwood also must not be piled upon the ground, but be well skidded
under, so as to be kept quite free from the effects of any damp from the
soil.

"After the trees are cut down, the longer they are exposed the more
danger is there afterward of the wood splitting more than is absolutely
necessary during the necessary seasoning before shipment to this
country.

"If shipped green, there is great danger of the wood sweating and
becoming mildewed during transit, which causes the wood afterward to dry
light and of a defective color, and in fact rendering it of little value
for commercial purposes.

"There is no occasion to strip the bark off or to put cowdung or
anything else upon the ends of the pieces to prevent their splitting.

"Boxwood is the nearest approach to ivory of any wood known, and will,
therefore, probably gradually increase in value, as it, as well
as ivory, becomes scarcer. It is now used very considerably in
manufacturing concerns, but on account of its gradual advance in price
during the past few years, cheaper woods are in some instances being
substituted.

"Small wood under four inches is used principally by flax spinners for
rollers, and by turners for various purposes, rollers for rink skates,
etc., etc., and if free from splits, is of equal value with the larger
wood. It is imported here as small as one a half inches in diameter, but
the most useful sizes are from 21/2 to 31/2 inches, and would therefore,
we suppose, be from fifteen to thirty or forty years in growing, while
larger wood would require fifty years and upward at least, perhaps we
ought to say one hundred years and upward. It is used principally for
shuttles, for weaving silk, linen, and cotton, and also for rule making
and wood engraving. _Punch, The Illustrated London News, The Graphic_,
and all the first class pictorial papers use large quantities of
boxwood."

In 1880, Messrs. Churchill and Sim reported favorably on some
consignments of Indian boxwood, concluding with the remarks that if the
wood could be regularly placed on the market at a moderate figure, there
was no reason why a trade should not be developed in it. Notwithstanding
these prospects, which seemed promising in 1877 and 1880, little or
nothing has been accually done up to the present time in bringing Indian
boxwood into general use, in consequence, as Mr. Gamble shows, of
the cost of transit through India. The necessity, therefore, of the
discovery of some wood akin to box is even more important now than ever
it was.

BOXWOOD SUBSTITUTES.

First among the substitutes that have been proposed to replace boxwood
may be mentioned an invention of Mr. Edward Badoureau, referred to in
the _Gardeners' Chronicle_, March 23, 1878, p. 374, under the title of
artificial boxwood. It is stated to consist of some soft wood which has
been subject to heavy pressure. It is stated that some English engravers
have given their opinion on this prepared wood as follows:

It has not the power of resistance of boxwood, so that it would be
imposible to make use of it, except in the shape of an electro obtained
from it, as it is too soft to sustain the pressure of a machine, and
would be easily worn out. In reply to these opinions, Mr. Badoureau
wrote: "My wood resists the wear and tear of the press as well as
boxwood, and I can show engravings of English and French artists which
have been obtained direct from the wood, and are as perfect as they are
possible to be; several of them have been drawn by Mr. Gustave Dore."

Mr. Badoureau further says that "while as an engraver he has so high an
opinion of the qualities of compressed wood as a substitute for boxwood,
as the inventor of the new process he considered that it possesses
numerous advantages both for artistic and industrial purposes." In
short, he says, "My wood is to other wood what steel is to iron."

The following woods are those which have, from time to time, been
proposed or experimented upon as substitutes for boxwood, for engraving
purposes. They are arranged according to their scientific classification
in the natural orders to which they belong:

_Natural Order Pittosporeae_.

1. _Pittosporum undulatum_. Vent.--A tree growing in favorable
situations to a height of forty or even sixty feet, and is a native of
New South Wales and Victoria. It furnishes a light, even grained wood,
which attracted some attention at the International Exhibition in 1862;
blocks were prepared from it, and submitted to Prof. De la Motte, of
King's College, who reported as follows:

"I consider this wood well adapted to certain kinds of wood engraving.
It is not equal to Turkey box, but it is superior to that generally used
for posters, and I have no doubt that it would answer for the rollers
of mangles and wringing machines." Mr. W.G. Smith, in a report in the
_Gardeners' Chronicle_ for July 26, 1873, p. 1017, on some foreign woods
which I submitted to him for trial, says that the wood of _Pittosporum
undulatum_ is suitable only for bold outlines; compared with box, it is
soft and tough, and requires more force to cut than box. The toughness
of the wood causes the tools to drag back, so that great care is
required in cutting to prevent the lines clipping. The average diameter
of the wood is from 18 to 30 inches.

2. _Pittosporum bicolor_, Hook.--A closely allied species, sometimes
forty feet high, native of New South Wales and Tasmania. This wood is
stated to be decidedly superior to the last named.

3. _Bursaria spinosa_, Cav.--A tree about forty feet high, native of
North, South, and West Australia, Queensland, New South Wales, Victoria,
and Tasmania, in which island it is known as boxwood. It has been
reported upon as being equal to common or inferior box, and with
further trials might be found suitable for common subjects; it has the
disadvantage, however, of blunting the edges and points of the tools.

_Natural Order Meliaceae_.

4. _Swietenia mahagoni_, L. (mahogany).--A large timber tree of
Honduras, Cuba, Central America, and Mexico. It is one of the most
valuable of furniture woods, but for engraving purposes it is but of
little value, nevertheless it has been used for large, coarse subjects.
Spanish mahogany is the kind which has been so used.

_Natural Order Ilicineae_.

_Ilex opaca_, L. (North American holly).--It is a widely diffused tree,
the wood of which is said to closely resemble English holly, being white
in color, and hard, with a fine grain, so that it is used for a
great number of purposes by turners, engineers, cabinet makers, and
philosophical instrument makers. For engraving purposes it is not equal
to the dog-wood of America (_Cornus florida_); it yields, however, more
readily to the graver's tools.

_Natural Order Celastrineae_.

6. _Elaeodendron australe_, Vent.--A tree twenty to twenty-five feet
high, native of Queensland and New South Wales. The wood is used in the
colony for turning and cabinet work, and Mr. W.G. Smith reports that for
engraving purposes it seems suitable only for rough work, as diagrams,
posters, etc.

7. _Euonymus sieboldianus_, Blume.--A Chinese tree, where the wood,
which is known as pai'cha, is used for carving and engraving. Attention
was first drawn to this wood by Mr. Jean von Volxem, in the _Gardeners'
Chronicle_ for April 20, 1878. In the Kew Report for 1878, p. 41, the
following extract of a letter from Mr. W.M. Cooper, Her Majesty's Consul
at Ningpo, is given: "The wood in universal use for book blocks, wood
engravings, seals, etc., is that of the pear tree, of which large
quantities are grown in Shantung, and Shan-se, especially. Pai'cha is
sometimes used as an indifferent substitute. Pai'cha is a very fine
white wood of fine fiber, without apparent grains, and cuts easily; is
well suited for carved frames, cabinets, caskets, etc., for which large
quantities are manufactured here for export. The tree itself resembles
somewhat the _Stillingia_, but has a rougher bark, larger and thinner
leaves, which are serrated at the edge, more delicate twigs, and is
deciduous." In 1879, a block of this wood was received at the Kew
Museum, from Mr. Cooper, a specimen of which was submitted to Mr. Robson
J. Scott, of Whitefriars Street, to whom I am much indebted for reports
on various occasions, and upon this wood Mr. Scott reported as follows:
"The most striking quality I have observed in this wood is its capacity
for retaining water, and the facility with which it surrenders it. This
section (one prepared and sent to the Kew Museum), which represents
one-tenth of the original piece, weighed 3 lb. 41/2 ounces. At the end of
twenty one days it had lost 1 lb. 63/4 ounces in an unheated chamber. At
the end of another fourteen days, in a much elevated temperature, it
only lost 1/4 ounce. In its present state of reduced bulk its weight is 1
lb. 10 ounces. It is not at all likely to supersede box, but it may be
fit for coarser work than that for which box is necessary." Later on,
namely in the Kew Report for 1880, p. 51, Mr. R.D. Keene, an engraver,
to whom Mr. Scott submitted specimens of the wood for trial, writes: "I
like the wood very much, and prefer it to box in some instances; it is
freer to work, and consequently quicker, and its being uniform in color
and quality is a great advantage; we often have great difficulty in
box in having to work from a hard piece into a soft. I think it a very
useful wood, especially for solid bold work. I question if you could get
so extreme a fine black line as on box, but am sure there would be a
large demand for it at a moderate price." Referring to this letter, Mr.
Scott remarks that the writer does not intend it to be understood that
pai'cha is qualified to supersede box, but for inferior subjects for
which coarse brittle box is used. Mr. Scott further says that of the
woods he has tried he prefers pear and hawthorn to pai'cha.

_Natural Order Sapindaceae_.

8. _Acer saccharinum_, L. (sugar or bird's eye maple).--A North American
tree, forming extensive forests in Canada, New Brunswick, and Nova
Scotia. The wood is well known as a cabinet or furniture wood. It has
been tried for engraving, but it does not seem to have attracted much
notice. Mr. Scott says it is sufficiently good, so far as the grain is
concerned. From this it would seem not to promise favorably.

_Natural Order Leguminoseae. Sub-order Papilionaceae_.

9. _Brya ebenus_, [Delta]. DC.--A small tree of Jamaica, where the wood
is known as green ebony, and is used for making various small articles.
It is imported into this country under the name of cocus wood, and
is used with us for making flutes and other wind instruments. Mr.
Worthington Smith considers that the wood equals bad box for engraving
purposes.

_Natural Order Rosaceae_.

10. _Pyrus communis_, L. (common pear).--A tree averaging from 20 to 40
feet high. Found in a wild state, and very extensively cultivated as a
fruit tree. The wood is of a light brown color, and somewhat resembles
limewood in grain. It is, however, harder and tougher. It is considered
a good wood for carving, because it can be cut with or across the grain
with equal facility. It stands well when well seasoned, and is used for
engraved blocks for calico printers, paper stainers, and for various
other purposes. Pear-wood has been tried for engraving purposes, but
with no great success. Mr. Scott's opinion of its relative value is
referred to under pai'cha wood _(Euonymus sieboldianus)_.

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