ATLAS OF ABSORPTION SPECTRA

BY

H. S. UHLER and R. W. WOOD

WASHINGTON, D. C:

Published by the Carnegie Institution of Washington

May, 1907

CARNEGIE INSTITUTION OF WASHINGTON
Publication No. 71.

PRESS OK THE WILKKNS-SHEIRY PRINTING CO.
WASHINGTON, D. C.

INTRODUCTION.

By R. W. Wood.

In spite of the ven' large amount of work which has been done on ab-
sorption spectra, there exists practically no collection of photographed spectra
from which one can pick out the media most suitable for any particular line
of investigation. The greater part of the published records are drawings
made from visual observations, and give no information regarding the optical
properties of the media in the ultra-violet. It seems desirable therefore to
compile a set of photographic records which are free from the errors liable
to enter into observations made by visual methods, and to arrange them in
such a way that the medium or media necessary to secure a desired result
could be readily found from a mere inspection of the plates.

A great deal of experimental work was necessarj^ before satisfactory^
photographic records were obtained. The details of the spectrograph and
the refinements of the method have been worked out very skilfully by
Dr. Uhler, who has done practically all of the experimental work. It was
our original plan to include the colored salts of metals, and to examine a
large number of colorless substances for peculiarities in the ultra-violet. The
solutions of the inorganic compounds could not, however, be investigated
in precisel}' the same manner, owing to their less powerful absorption. Much
thicker absorbing wedges were required, and these gave trouble, even when
compensated, as a result of dispersion. It was therefore decided to limit
the present work chiefly to a study of the aniline dyes, which are used to a
much greater extent than the metallic salts, in the preparation of absorbing
screens. The absorption spectra of a number of metallic salts, however,
have been photographed, as it is believed that many of them will be useful
in the preparation of ray filters ; some of them are far more transparent in
the ultra-violet than the aniline dyes. Even such substances as the salts
of erbium, neodymium, and praseodymium are useful in special cases where
it is desired to suppress one or more isolated spectral lines. For example,
a solution of neodymium has a very narrow and intense band coincident with
the D lines, and has therefore the property of cutting out the sodium radia-
tion from a given source, transmitting at the same time nearly the whole of
the remainder of the spectrum. The same salt can be used to advantage
when working with the new cadmium and zinc arc lamps in quartz tubes,

43948

2 ATLAS OF ABSORPTION SPECTRA.

made by Heraeus. The fact that the absorption of each substance in the
ultra-violet is recorded, makes the plates of especial value to anj^ engaged
in the preparation of screens for spectroscopic or photographic purposes.

For the removal or transmission of one or more isolated lines some
other arrangement is often more useful than an absorbing screen. A
spectroscope with a slit placed in the focus of the observing telescope
(monochromatic illuminator) is frequenth' all that is necessary. But if more
light is required, the following device may be used. A block of quartz from
2 to 4 cm. in thickness, cut perpendicular to the optic axis, is mounted
between two Nicol prisms. The transmitted spectrum is crossed by black
bands, which result from the rotatory power of the quartz. By adjusting
the nicols and varying the thickness of the quartz it is often possible to get
rid of the spectrum lines which are not desired, and at the same time to
utilize the whole area of the source, which can never be done with the spec-
troscope. In this wa}^ with a quartz plate 45 mm. thick, the line 4809 of
the zinc arc in quartz can be completely removed and the two lines 4721
and 4679 transmitted. This method is especiall}' useful in the study of the
fluorescence excited in various bodies by monochromatic light.

If it is necessar}' to separate radiations of very nearh' the same wave-
length, for example if we wish to work with the light of one of the two
sodium lines, the following arrangement can be used : A quartz plate about
2 cm. in thickness, cut parallel to the axis, is mounted between crossed nicols,
with its axis making an angle of 45° with the principal planes of the polar-
izing prisms. The source is placed behind a vertical slit 2 or 3 mm. in
width, and the light, after traversing the polarizing system is brought to a
focus by a lens. A number of concentric maxima and minima will be
formed, the light of Di and Dg being found in adjacent maxima. The
wave-length which is not desired can be stopped by a screen of suitable
dimensions placed at the focus of the lens. In this waj' it is possible to
obtain a source of Di or D2 radiation of sufficient intensity to show distinct
fringes in a Michelson interferometer. By a curious coincidence this method
occurred independently to the writer and to Professor Michelson on the same
day. It has been found to give excellent satisfaction. The thickness of
the quartz plates used in either of the above cases depends upon the close-
ness of the lines which it is desired to separate.

We are under great obligation to the Actiengesellschaft fiir Anilinfabrika-
tion and to Meister, Lucius & Briining, both of which firms presented the
Johns Hopkins University with a large collection of aniline dyes.

ATLAS OF ABSORPTION SPECTRA.

OBJECT OF THE PRESENT INVESTIGATION,

If we look over the literature of the subject of absorption of light we
fail to find a collection of absorption spectra presented in such a manner as
to enable the observer to select at a glance a substance which produces
either general or selective absorption in any specihed part of the visible or
ultra-violet spectrum. The wave-lengths of the absorption bands and other
characteristics of the absorption exhibited by innumerable natural and arti-
ficial compounds and mixtures, both inorganic and organic, may be found
in a great many books, journals, memoirs, and dissertations. If all of these
results were reproduced and catalogued in one volume they would not satis-
factorily fulfil the requirements just mentioned, because the different experi-
menters have had various objects in view and hence they have worked in
various and limited parts of the spectrum, have used different numerical
dispersions, have employed optical systems of unlike dispersion curves, have
not made it possible even to reduce their results to graphical form much less
to a common basis of wave-lengths and normal dispersion, etc. The nearest
approach to a work of the kind under consideration is made by the publica-
tions of J. Formanek, especially the two volumes entitled respectively ' ' Die
Qualitative Spektralanalyse anorganischer Korper" and "Spektralanaly-
tischer Nachweis kiinstlicher organischer Farbstoffe ; " Berlin, 1900. For-
manek's investigations are very extensive and complete from the point of
view explicitly stated in the preface to the last-named volume. It was his
aim to develop a practical spectroscopic method of procedure by which any
given organic coloring matter could be unambiguously identified. He says:

" Das Princip des hier beschreibenen neuen Verfahrens beruht auf der Kombina-
tion der spektralanalytischen Beobaclitung und der chemischen Untersuchuug ; dieses
Verfahreu liefert nicht nur sichere Resultate, sondern sein Vortheil liegt auch darin,
dass man mit Hilfe desselben alle eiuzelnen Farbstoffe von einander unterscheiden
kann."

Formanek, in order to obtain his results, varied the concentrations of
his solutions until each absorption band of a given substance became in suc-
cession as well defined as possible, so that the wave-lengths of their maxima
might be read off with precision. This method is preeminently adapted to
locating maxima, but it gives very little, if any, information relative to the
absorption between and beyond the maxima, for bodies exhibiting marked

4 ATLAS OF ABSORPTION SPECTRA.

selective absorption, and it tells even less about substances presenting
weak, general absorption. Another important respect in which Formanek's
diagrams fail to give the data required by the first sentence of this section is
that he confined his measurements to eye observations, unaided by phos-
phorescent screens, and hence he omitted the entire ultra-violet region.
In fact, his wave-lengths have the limits 420/j',« and 741,"/^, i. e. , from
"above" the G line to a little " below " the a line. Formanek used a prism
spectroscope to the dispersion of which he gives no clue.

To fill in this gap in the then existing collections of absorption spectra
the present research was begun in the spring of 1903. Its chief object is to
furnish graphical representations, on a normal scale of wave-lengths, of the
absorption spectra, both in the visible and in the 7(ltra-violet regions, of a reasoft-
ably large number of compounds.

The most obvious use to which such a collection can be put is the pro-
duction of color screens either for photographic work or for removing higher
orders of spectra from the first order, in the case of diffraction gratings. It
also makes possible the selection of such solutions as will transmit relatively
narrow, and hence roughl}^ monochromatic, regions of the spectrum. Such
solutions are often convenient substitutes for somewhat elaborate pieces of
apparatus which first disperse the light by a prism (or grating) and then
permit any desired portion of the resulting spectrum alone to continue unin-
terrupted by means of a suitable slit and screens. Other directions in which
the data given below may be of practical value need not be pointed out here.

SELECTION OF MATERIAL, APPARATUS, ETC.

That a great deal of time was consumed in constructing apparatus and
in performing preliminar}' experiments is shown by the fact that, although
the investigation was entered upon in the spring of 1903, it was not until
July, 1904, that the first really satisfactory negative was obtained. Only
aqueous solutions of the aniline dyes have been investigated up to the present
time. As is well known, the position of an absorption band may be shifted
within wide limits by varying the solvent ; * moreover, many aniline dyes
are insoluble, or nearly so, in water. On this account it would have been
desirable to have made use of the alcohols, benzol, and other organic com-
pounds as solvents for the media under investigation. But difficulties were
met with which were not overcome until the stud}' of the dyes was completed.
Chief among them may be mentioned the rapid evaporation of the fluid held
between the quartz plates. Attempts were made to obviate the difficulty by
painting the edges of the wedge with melted paraffin, but the heat of the
spark was sufficient to drive off the greater part of the fluid before the

*See Nos, 158 and 165.

SELECTION OF MATERIAL, APPARATUS, ETC. 5

exposure was finished. Water is, however, the solvent generall}' used, and
the easiest one to manage. It is moreover free from ultra-violet absorp-
tion, which is not true of the majority of the other solvents available, and
all dyes which can be dissolved in water can be used for staining gelatin
films. The gelatin can be dissolved in the solution of the dye and clean
glass plates flowed with the warm solution, or an unexposed photographic
plate, after preliminary treatment with thiosulphate of soda and thorough
washing, ma}- be stained with the solution of the dye. It is probable that
the position of the absorption bands is the same in gelatin as in water, for
the indices of refraction of the two media are very nearly the same.

ABSORBING MEDIA.

Because of their great variety, strong selective absorption, and general
interest, aniline dves and their related organic compounds were selected as
best suited for the study contemplated.

DISPERSING SVSTEM.

In order to obtain reasonably normal spectra a spherical, concave,
speculum grating, whose radius of curvature was 98.3 cm., was used. For
the first order spectra and for short photographic exposures the astigmatism
of the reflector did not produce deleterious effects. This was determined
by actual measurements. The length of one line of the ruling was 1.96 cm.,
and the assemblage of lines covered 5.36 cm. The spectroscopic resolving
power was 21,250 (2.125 inches with 10,000 lines per inch). The incon-
venience of superposed higher orders will be mentioned later on. To obtain
a general idea of the normality of the spectrograms and of the linear dis-
persion it may be stated that, by calculation one millimeter the center of
which was at 214.7.",", or 399.4,",^, or 656.3,","., covered 25.77, 25.84, and
25.71 A. U., respectively, for the spectrum was designed to be normal at
the air line 399. 4,"/^.

PHOTOGRAPHIC MATERIAL.

Because of the short radius of curvature of the focal surface (about 49
cm.) celluloid films were employed in most cases. The films used through-
out were M. A. Seed's "L-ortho cut negative films," size 5 by 7 inches.
The emulsion is by no means equally sensitive over the field of wave-lengths
studied, i. e., from 0.2," to 0.63,". The chief maximum of sensitiveness is
in the 3'ellow, about 0.56,". A much weaker maximum is near 0.49,". The
middle of the less sensitive intervening region is ver}' roughly 0.52//.

For the short exposures given throughout, these films are not appreciabl}-
influenced b}- wave-lengths longer than about 0.61,". The resultant effect of
the Nernst glower and the Seed emulsion is best understood by referring to
fig. 102, plate 26, for which the times of exposure were, in order, 2 seconds,
5 seconds, 15 seconds, 30 seconds, i minute, 2 minutes, and 3 minutes.

6 ATLAS OF ABSORPTION SPECTRA.

Various schemes to make the resultant action more uniform were tried
and other makes of films were tested, but no improvement on the simple
combination of the Seed emulsion and the Nernst glower resulted, therefore
the}' were used almost exclusively. The Seed films are good in the ultra-
violet as is shown by the fact that with an exposure of 5 minutes the alumin-
ium line at 185///* was clearly recorded. To see if appreciable shifts in the
apparent positions of the absorption bands were produced by the yellow
maximum and the green minimum of the Seed films, negatives of the same
absorbing medium, under exactly the same conditions, were taken on sev-
eral different makes of films and plates which did not exhibit maxima and
minima of sensitiveness for the same wave-lengths. Also, other and inde-
pendent tests of this possible source of error were made. The conclusion
was that no noticeable displacements of the bands were caused. However,
in the cases of brown and other visibly colored solutions, exhibiting weak,
general absorption, the observer of the appended positives must be careful to
distinguish between true absorption and the spurious effects in the vicinity
of 0.52,'/.

In photographing bands in the orange and red, Cramer "Trichromatic"
plates were found to be the best and hence they were used. The plates
being plane they had to occupy a mean position with respect to the focal
surface of the grating. Since only a comparatively small region of wave-
lengths was thus recorded, no measurable errors were introduced. In fact,
in the region considered, the second order ultra-violet of a discontinuous
spectrum taken on a film and on a plate could be superposed fine for line.

The developer used was a simple hj'drochinone solution made up
according to Jewell's formula.*

SOURCES OF LIGHT.

For wave-lengths from "above" 0.65,". to "below" 0.326//., and for
exposures of about one minute, the Nernst glower was found to be the most
satisfactory. Prevailing circumstances made desirable the use of 104 volt
glowers on a circuit carrying about 133 cycles. The emissivity of the Nernst
lamp varies so very greatly with the e. m. f. impressed upon its terminals
that it was obligatory to keep in series with the glower a Thomson A.C.
ammeter having a range from zero to two amperes and graduated directly
to 0.02 ampere. Fluctuations of more than 0.02 ampere invariably resulted
in a 'spoiled photograph, consequently boxes containing variable metallic
resistance were maintained in series with the ammeter and thus, in spite of
large changes in the load on the dynamo, due to other experimental circuits,
it was possible to prevent the effective current in the filament from changing

* L. E. Jewell. Astrophys. Jour., v. xi, 1900, pp. 240-243.

SELECTION OF MATERIAL, APPARATUS, ETC. 7

by more than o.oi ampere. The current was usually 0.8 ampere or a little
less. The ammeter was appreciabl}' more sensitive to small changes in the
terminal voltage than a comparably graduated Thomson A. C. voltmeter,
because the current shunted through the voltmeter was not negligible in
comparison with the current which fed the glower. Among other sources the
electric arc was given a fair trial and discarded for two reasons, first, because
of the intensity of the carbon and C3'anogen bands, and second, because of
the inconveniences resulting from its unsteadiness and great emission of heat.

For wave-lengths between the strong ultra-violet of the Nernst glower
and o. 2,a a spark discharge in air of about i cm. length was used. In obtain-
ing the greater number of the negatives one electrode was composed of an
alloy of equal parts by weight of cadmium and zinc and the other was made
of sheet brass. The alloy wore away so rapidly that the brass electrode was
employed to reduce the labor attendant upon sharpening the terminals.
The electrodes were given a form apparently not
described before. As is very well known, manj^
spectral lines, both weak and strong, produced

b}^ sparks between metallic surfaces extend only :^"'"~~"tii^' ^

a short distance beyond the metal and hence do '''^•i^::\f^h::^:'^ii;i ^p'^''^

not offer a continuous source of light! across the t " ' r'' (V

entire spark gap. In order to obtain a back-
ground of uniform intensity from edge to edge
of the negatives it was necessary' to use some Fig. 1.— Flat and edge views,

scheme to nullify the effects of the non-uniformity of emission in the spark.
One way of accomplishing this is to rapidly translate the electrodes (main-
tained at a fixed distance apart) back and forth parallel to the length of
the slit of the spectrograph by some mechanical device.

The reciprocating action associated with this plan shakes the camera
and grating to such an extent as to demand greater rigidity in the apparatus
than it usually has. Therefore the electrodes were made in the shape of
wedges or chisels with the sharp edges parallel to the slit. The well-known
distribution of a rapidly alternating current in a conductor necessitated
curving the edges of the electrodes, as is shown in fig. i, which is Ji natural
size. Due to the tearing away of the metal, and to various other causes,
the innumerable thread-like sparks changed the positions of their ends so
rapidly that the integrating action of the photographic film recorded a
perfectly uniform negative for exposures of 15 seconds or more. The
exposures generally lasted 75 seconds. The electrodes had to be kept sharp
and smooth, for, when this was neglected, the elementary sparks persisted
much longer in one position than in another and consequently caused streaks
of varying intensity to run along the negatives parallel to their length, as
can be seen in some of the positives reproduced in the appended plates, e.g.,
fig. 99, plate 25.

8 ATLAS OF.IaBSORPTION SPECTRA.

The current for the spark was obtained in the following manner: An
alternating e. m. f. of about io6 volts (133 cycles) was impressed on the
terminals of an induction coil of unknown ratio of turns. Eight or nine
amperes commonly flowed in the primary. The interrupter of the coil was
thrown out of circuit and the coil therefore performed the functions of a
transformer. In parallel with the secondary was placed a Le3fden jar about
18 inches high and of unmeasured capacity. No auxiliary spark was intro-
duced. The system could spark about 2.5 cm. in air between metallic
points.

The great intensity of some of the lines characteristic of all the common
metals tried (Al, Cd, Cu, Fe, Pb, Zn, etc.) made these metals undesirable
for the present work. Cadmium and zinc were selected only because of the
strong continuous background to which they give rise. Uranium, its salts or
its earths were not used in this work because they are unmanageable.
Naturally the pure metal in air burns to oxide at once; pitchblende can not
be worked into a suitable shape (at least, for such specimens as we have
been able to obtain); and, pitchblende is so very heterogeneous that the
position of the spark can not be depended upon for an instant. To have
employed a neutral atmosphere in conjunction with a reciprocating mechanism
would have consumed, obviously, too much time and would have demanded
too complicated, cumbersome and inconvenient an assemblage of apparatus.

THE CELL.

In order to show the variations in the absorption spectrum of a given
substance when the thickness of the absorbing layer changed linearly, a
wedge-shaped cell was constructed. Vessels made on this principle have
been designed and used often before, notably by Angstrom, Gladstone, Govi,
Gibbs, Tumlirz, Hodgkinson, F. Melde, Hartley, and others.* Neverthe-
less, because the precise form of the cell is supposedly new and certainly
useful it may not be superfluous to enter into a detailed description of it
here. This little piece of apparatus was designed so that the relative posi-
tions of the quartz surfaces through which the light entered into, and emerged
from, the absorbing liquid could be varied at will, within certain limits. In
other words, matters were so arranged that the liquid could be in the form
either of a wedge, of variable angle, with zero thickness at the refracting
edge, or of a prism of variable angle and finite depth throughout, or of a
plane-parallel layer of changeable thickness. To satisfy these conditions it
was convenient to rely upon gravitation to preserve certain parts of the cell
in mutual contact. This in turn necessitated both the horizontal position of

* See H. Kayser, " Handbuch der Spectroscopie, " v. in, pp. 58, 59.

T'

T

^

n

t

H

. i

o

O O 0

SELECTION OF MATERIAL, APPARATUS, ETC. 9

the bottom of the cell and (because it was desirable to reduce the number of
reflecting surfaces to a minimum) a vertical t\^pe of spectrograph.

The cell comprised live separable parts, as follows: (i) A brass frame-
work upon which the other parts rested; (2) a transparent tray, without a
lid, which confined the liquid in proper bounds; (3) a transparent boxlike
S3'stem which gave the upper surface of the liquid the desired position; (4) a
vulcanite framework to hold the last mentioned box in place ; and (5) four
mahogan)' pins or pegs to fasten the box to its framework.

(i) A side view of this framework is presented in figure 2. There
were three micrometer screws, all of the same pitch, viz : i turn =^ k in.

^0.053 cm. The heads
of the screws were grad-
uated, on their upper sur-
faces, in ten equal parts.
Fig. 2.-Four-fifths natural size. The scrcw T was in the

medial plane of the cell while the remaining screws (T' only is shown) were at
the other end of the system, were equidistant from this plane, and were as far
apart as possible. The micrometer screws called for vertical scales on the
adjacent brass-work to count whole turns. The handle is denoted by HH.
A black fiducial mark, F, on a white ground, enabled the experimenter to
tell what position the cell occupied with reference to the length of the slit of
the spectrograph. The lower end of F moved over a scale parallel to the
slit and in the plane of the jaws of the latter. The flange at the bottom of
the framework was made of brass only 0.014 cm. thick so that the absorb-
ing medium might be as near the slit as possible.

(2) An accurately ground, plane-parallel plate of quartz 40 mm. long,
18.5 mm. ^yide, and 2 mm. thick had cemented to its periphery four
rectangular sheets of thin glass 8 mm. high. Hence, the greatest depth of
liquid which could be studied by the aid of this cell was 6 mm.

(3) In figure 3, a, 6, c, and d designate the vertices
of the section of a quartz plate, made by a plane per-
pendicular to the plane the trace of which is the line

M M

O O

ad. ad was 2 mm., ad wa.s 34.8 mm., and the angle Fig. 3.— Four-fifihs nat. size,
between the planes of ad and dc was 55 minutes of arc. The horizontal
width of the wedge was 10 mm. Glass walls surrounded three sides of the
wedge, as the outline indicates. The reason for using the quartz wedge was
to counteract the deviation and dispersion produced by the solution in the
cell. The angle of the liquid wedge could be varied until the deviation
effected by the quartz wedge nullified the average action of the absorbing
solution. At first it was supposed that with liquid wedges of 15 or so
minutes of arc a plane-parallel quartz plate could be used successfully instead

lO

ATLAS OF ABSORPTION SPECTRA.

1

■

1

^

, j

P

1 .

1

F'

"

M

p'

of the quartz wedge. This was true for some dyes but for concentrated
solutions of certain other dyes (notably the sodium salt of /-methoxy-
toluene-azo-/5-naphthol-di-sulphonic acid) some compensating sj'stem was
absolute!}' necessary. Finally, the quartz wedge was made with the utmost
care by an expert optician, special pains being taken to have the edge
through d, perpendicular to the plane aicd, as sharply defined as possible,
and the surfaces whose traces are denoted by ad and dc were accurately
plane.

(4) Figure 4 presents a side view and an end view of the vulcanite frame
into which the quasi-box just described fitted. This frame was shaped

out of a single block of vulcanite, for
experience showed that a cemented
system of several pieces was not dur-
able; also a dielectric was needed to
keep the sparks from jumping to the
screws. P indicates a httle depression
Fig. 4— Four- fifths natural size. which fitted over the point of the

screw T. P' designates the end of a straight line along which the rounded
extremity of the screw T' slid. P" is the cross-section of a shallow,
V-shaped groove along which the pointed end of the third screw, T", like-
wise slid. The perforations M, M', etc., correspond to each other and to
the associated wooden pegs mentioned above as (5).

Figure 5 is an unconventional
sketch of the cell when completely
assembled.

A cell of the construction just
described is very well suited to the
study of thin layers of solutions in solvents of relatively high boiling-points,
such as water and amyl alcohol, but, unless inclosed in some suitable vessel,
it is not applicable to solvents of lower boiling-points like ethyl alcohol,
ether, chloroform, etc.

CEMENTS.

A few words concerning cements may not be superfluous because a great
many receipts were tried and none was considered entirely satisfactory.
No single cement was found which satisfied the following three necessary
conditions : (a) Of being unaffected by hot or cold water ; {d) of being insolu-
ble in the alcohols, ether, chloroform, carbon bisulphide, etc. ; (c) of drying
or setting in three or four days, at most.

The plan used by Prof. H. N. Morse, in waterproofing cells for the
study of osmotic pressure, gave the best results and hence it was followed

Fig. 5.

SELECTION UF MATERIAL, APPARATUS, ETC.

II

.in fastening together the quartz and glass parts of the cell described in the
last section. These parts were first fastened together with Khotinsky
cement in the usual way, that is, by heating them in an air bath, to any
convenient temperature above the melting point of this cement, and by
heating a stick of the adhesive mixture in a Bunsen flame and then applying
it to the surfaces of the hot quartz and glass.

Since this resinous cement is soluble in ethyl and amyl alcohol and other
solvents, and because it is attacked by various liquids, such as an aqueous
solution of potassium permanganate, it was necessary to coat the exposed sur-
faces of the cement with something which was chemically inert towards the
solutions to be studied. Such a substance is a solution of rubber in carbon
bisulphide. This solution was made and used as follows: From an adequate
length of black, soft, rubber connecting-tubing segments about 2 cm. long
were cut and heated in an evaporating dish over a Bunsen flame until the
sections fused, ran together, and formed a very sticky, viscous liquid. (A
single long piece of tubing does not liquefy at all satisfactorily.) The liquid
state persisted after the contents of the evaporating dish had been allowed
to cool down to about room temperature. Carbon bisulphide was next
poured into the dish and the contents of the latter were stirred until a
homogeneous solution resulted.

The relative proportions of the carbon bisulphide and rubber used were
immaterial and were determined by convenience only The solution can be
retained indefinitely in a tightly stoppered bottle and used whenever needed.
A thin layer of the solution was painted over the Khotinsky cement, after
which the quartz-glass system was heated in an air bath at about 100° C.
until the layer became dry and hard, and was no longer sticky. (Of course,
during the first part of the process the transparent elements of the cell had
to fit over a suitable wooden "form," because Khotinsky cement softens too
much at 100° C. to maintain objects in their proper relative positions.) After
this another thin coat of the rubber solution was applied and the heating
continued. This succession of operations was repeated until a thick, hard,
dark-brown covering for the joints was obtained. It then made little differ-
ence whether the original cement were present or not, as the hard rubber
held the quartz and glass together very satisfactorily.

A cement which dissolves readily in water and in acetic acid but which
is not affected by ethyl alcohol, amyl alcohol, carbon bisulphide, glycerin,
chloroform, ether, benzol, nitrobenzol, aniline oil B, benzaldehyde, toluol,
etc., is made by dissolving 2 pounds of pure gelatin in one quart of water and
adding to the resulting solution 7 ounces of nitric acid (sp. gr. 1.35 to 1.42).
The final solution is colorless and when applied in thin layers dries in a day
or so. It is called Dumoulin's liquid glue. This glue does not keep well.

12 ATLAS OF ABSORPTION SPECTRA.

even in a tightly stoppered bottle, and is best made up fresh just before
being applied as an adhesive.

Since the completion of the experimental work on the aniline dj-es a
cell, in the construction of which no cement at all was employed, has been
designed and successfully used by one of us.* This cell could retain any
liquids which would not attack glass and quartz and, although it was
designed to confine the solutions in plane-parallel layers, nevertheless, the
principles involved in its construction were such as to admit of extension to
the production of a cell which would be wedge-shaped in the interior and
would, at the same time, hold organic solvents, prevent evaporation, etc.

THE SPECTROGRAPH.

The essential parts of a vertical section of the spectrograph are outlined
in figure 6. They may be tersely described, with the aid of symbols,
as follows: In the first place, the elements of the system were adjustable
in every respect. Light from the Nernst filament, N, was focused by the
concave speculum mirror, R, on the slit, S, whence it continued to the
grating, G, from which a portion of it was dispersed in the direction of the
sensitized film, F. The distances from the middle of the slit to the centers
of the mirror and grating were respectively about 89. 5 cm. and 97. i cm.
The electrodes, E, were usually at the distance of 4. 2 cm. above the slit and
they did not interfere with the passage of the light from the reflector to the
slit. No lenses or other reflectors were used. The micrometer head at M
indicated the separation of the slit-jaws. Q and Q' denote a screen system
such that when Q was vertical the passage of light from the grating to the
camera was not interfered with, whereas when Q was horizontal only ultra-
violet light of shorter wave-length than 0.4,^ could reach the photographic
film. PP is a horizontal platform with a scale along its front edge. By
sliding projecting, horizontal, opaque screens of various widths along this
platform it was possible to cut out completely any region or regions of wave-
lengths desired.

In making certain tests, the platform and sliding screens were very
convenient. L is the section of a thin, black, metal shutter capable of
motion in a horizontal direction and hence at right angles to the length of
the photographic films ; in other words, parallel to the slit and to the rulings
of the grating. A number of long, rectangular slots or openings, suitably
spaced and proportioned, were present in this screen so that strips of differ-
ent widths of the films or plates could be exposed to the light from the
grating without causing any displacement of the sensitized surfaces with refer-

*The description of the details of the cell is given on pages 241 to 243 of Publication No. 60 of the
Carnegie Institution of Washington, entitled : Hydrates in Aqueous Solution. By Harry C. Jones.

THE SPECTRUGKAPII.

13

ence to the grating and slit. This was necessary for impressing comparison
spectra, etc. H and H' suggest the rack-and-pinion system by the aid of
which the lihns could have unexposed portions brought successively opposite
to some selected opening in the slide-screen L. D and D' denote two of

the four doors which gave access to
the interior of the spectrograph, and
which made it possible to close up
the camera light-tight, while making
various adjustments with the rest of the
system. The camera was made so
that, when it contained neither a film
nor a plate, it was possible for the
experimenter to look directly at the
grating and to make observations with
the assistance of an ej'e-piece.

Certain black-on-white scales and
ruby-glass windows (Z, for example)
enabled the experimenter to know the
precise relative positions of the various
accessories on the interior of the spec-
trograph, when the entire system was
shut up and exposures were being made.
Numerous dull black diaphragms and
screens (A), A2, Ay, Aj, A5, etc.) pro-
tected the photographic film from the
unusable light which came from the cen-
tral image, I, and from all the spectra
except the one desired. Ui and Oi
give the extreme rays of so much of the
first order spectrum as was studied,
that is, Ui and Oi correspond respec-
tively to about 0.201JL and 0.625^. Ob-
vioushs the spectrograph was dull black,
both inside and out, and contained
plaited black velvet in appropriate
places. A general idea of the size of
the apparatus may be derived from
the following dimensions: From R to
the plane of BC = 198.5 cm. ; BC
= 34. 5 cm. ; the bottom edge perpen-
dicular to BC = 27.5 cm.; BJ=ii6
cm. ; and JK = 29 cm.

Fig. 6. — One-lenth natural size.

14 ATLAS OF ABSORPTION SPECTRA.

MANNER OF EXPERIMENTING.

SOLUTIONS.

A small, known mass of a selected dye was carefully weighed on a
chemical balance, and put at the bottom of a medium-sized test-tube.
Then distilled water was run from a burette into the test-tube, and the
latter shaken up from time to time, until the resulting solution appeared to
have the proper concentration. As would be expected, practice produced
skill in judging absorption of visible light, but to get the right concentration
with respect to ultra-violet light was not always so eas}'. The greatest error
in measuring the solvents was about 0.2 per cent. Since the concentrations
are only intended to serve as general guides to an understanding of the
spectrograms, a higher degree of accuracy would have been superfluous.
Neither was there any reason, in general, for noting the volume of solutio7t
which contained a known number of grams of pure solvend; in other words,
changes in volume due to the processes of solution were not regarded.

ADJUSTMENT OF THE CELL.

Especial care was taken to remove all coloring matter from the cell
before introducing another solution into it. Dust caused more trouble than
anything else. After cleaning the quartz and glass elements of the cell the
various parts of the latter were assembled and, when a prism of liquid was
to be studied, the micrometer screws regulated in the following manner :
All the screws were turned down so as not to touch the vulcanite framework,
and thus to cause the quartz wedge to rest on the quartz plate. Then the
screw T had its point elevated again and again until it just touched the
deepest part of the depression P. {^Sce figures 2, 3, 4, and 5.) This
condition was attained by gently rocking the S3fstem around the edge d of
the quartz wedge, somewhat after the fashion of experimenting with certain
types of spherometer. Thus the zero position of the cell was determined,
before each experiment, of course. Next, guided by the circular and plane
scales, the observer turned up the screw T until the desired angle, between
the wedge and plate, was known to obtain. After this, the screw corre-
sponding to T' was turned up until its tip projected far enough into the groove
P" to prevent the quartz wedge and its accessories from sliding over the
quartz plate around the point T as pivot, but yet not far enough to raise the
vulcanite frame the least bit. Finally, a small amount of the solution was
poured into the cell and the latter was then placed on the very thin brass
sheet which rested upon and protected the jaws of the slit.

As soon as the cell was placed over the slit and the glower had been
lighted the cell was moved forward and backward, parallel to the slit, while
one edge of the field of view was examined with an ej'e-piece, until a position
of the cell was obtained for which the light passing through the quartz wedge

MANNER OF EXPERIMENTING. 15

at its refracting edge {d of figure 3) illuminated the very limit of the
field of view as seen through the chosen slot of the shutter (L of figure 6).
The position of the mark on the handle of the cell (F of figure 2), with
respect to the horizontal scale in the plane of the slit-jaws, was then read off.
If the cell were then moved, ever so little, in one direction the width of the
brightl}^ illuminated field could be seen to be less than the opening in the
shutter; whereas, if the cell were translated in the opposite sense no increase
in the width of the illuminated field occurred. At this opportunity, eye-
observations of the absorption between 0.400/j and 0.625/ji were always
made and the facts recorded.

When the concentration of the liquid in the cell was much too great or
far too small this instrument had to be cleansed and filled with a solution of
more suitable absorbing power, obviously, but when the concentration was
not too remote from the best value the effective depth of the cell was varied
until the desired result was obtained.

All three screws were raised and regulated in an obvious manner when
prisms of liquid having nowhere infinitesimal thickness were wanted. When
layers of liquid of uniform depth were studied a system much like that
shown in figure 3, but which had for bottom a plane-parallel plate of
quartz 2 mm. thick, was substituted for the quartz-wedge system.

CALIBRATION OF THE CELL.

The diedral angles formed by the cell were calculated from the dimen-
sions of the instrument, and also from measurements made with a spec-
trometer.

EXPOSURES AND SPECTROGRAMS.

The majority of the spectrograms consist of three distinct photographs
taken side by side and as close together as possible. {See the plates.) The
width of each photograph was practically the same as the width of the
opening in the shutter L. Numerous trials showed that this field of view
was completely filled with light, with no overlapping on the grating-side of
the opaque portions of the shutter, when the length of the slit was dia-
phragmed down to 10.5 mm. Consequently, the sht was limited to a length
of a very little more than this number and the cell was moved along exactly
10.5 mm. between the taking of two adjacent photographic strips on the
same film. By this means, the thickness of absorbing liquid through which
the light passed to the very edge of one photographic strip was equal to the
thickness subsequently traversed by the light which recorded itself at the
contiguous edge of the adjacent strip. Of course, the best appearing records
were obtained when the film holder, actuated by the rack-and-pinion system,
was moved, by an amount exactly equal to the width of the opening in the
shutter. A casual inspection of the positives reproduced in the appended

I 6 ATLAS OF ABSORPTION SPECTRA.

plates shows that mechanical shifts, in wave-lengths, of the strips on one
complete spectrogram, with reference to one another, exist. This may mar
the appearance of the photographs somewhat, but the ultra-violet spark lines
show the magnitude of the displacements so that corrections can be made,
and hence the ultimate scientific value of the results is not decreased.

The order of events in taking a complete negative of tJiree strips was
invariably as follows : The thickest layer of absorbing liquid was over the
opening of the slit first, then the intermediate layer, and last of all, the
thinnest layer, which usually tapered to infinitesimal depth. This sequence
enabled the comparison spectrum to be taken by moving the shutter, L,
without jarring the film-holder, so as to minimize the shift of this spectrum
relative to the adjacent photographic strip. For negatives of more than three
strips precisely the reverse succession was adopted because it was easier to
commence with the cell in adjustment and then to raise the quartz wedge
parallel to itself than to lower all three micrometer screws by the same
number of turns until the quartz wedge just barely came into contact with
the quartz bottom of the cell. With the screen Q horizontal the first expo-
sure with the spark was taken. The screen was lowered and the second
exposure was made, this time with the Nernst glower. These two exposures
produced the first of the three photographic strips. Next the film-holder
and cell were moved the proper distances, as explained above. The glower
and spark exposures followed in the order named. After again moving the
film-holder and cell, the fifth and sixth exposures were produced by
the spark and glower respectively. Finally the cell and diaphragm were
removed from the slit, another opening in the shutter was adjusted before
the film, and the comparison spectrum impressed. In general, the glower
exposures lasted 60 seconds, the ultra-violet exposures 75 seconds, and the
comparison exposures 35 seconds. The width of the slit was always 0.008
cm. In any one complete spectrogram the exposures to the Nernst light
were all equal to each other and those for the ultra-violet were related to
one another in the same manner. Experience showed that the intervals 60
and 75 seconds were best suited to cause the overlapping ends of the photo-
graphic impressions to blend as if they had been produced simultaneously
by light from a single source. With the longest exposures used, the light
from the glower did not affect the films and plates for wave-lengths as short
as 0.315// and, since the field photographed did not comprise wave-lengths
longer than 0.63,^, there was no trouble produced bj' the ultra-violet of the
second order. The screen Q took care of this matter so far as the spark
exposures were concerned. Figures 14 and 15, plate 4, indicate how the
processes just explained can be extended to negatives as wide as may be
desirable and hence to as deep la3'ers of absorbing liquid as may be wished.*

*0f course, a cell deeper than 6 ram. would be necessary if the matter were pushed very far.

RESULTS. 1 7

RESULTS.

INTERPRETATION OF THE CURVES.

If the distances from the edge of a positive which is adjacent to the
comparison spectrum (which edge therefore corresponds to zero depth of
liquid in the cell) to arbitrary points on the boundary of a sharply-defined
absorption curve be called ordinates, and if wave-lengths be considered as
abscissa?, we may say that the absorption constants* associated with any
two chosen wave-lengths are inversely proportional to the ordinates belong-
ing to these wave-lengths. This statement involves certain assumptions,
about emission curves and sensibility curves, a discussion of which will not
be given here.

If the edge of an absorption band is a straight line at right angles to the
length of the picture it means that the position of this side of the band
will not appreciably change with wide variations in the concentration of the
solution; in other words, the limit of absorption will remain at the same
wave-length regardless of the concentration. This is roughly the case in
figs. 4 and 15 of plates i and 4 at the respective wave-lengths o. 29/i and
0.515,^, and for most of the narrow bands of figs. 96, 100, and loi. If this
condition holds for all the bands of a given substance, which are within or
near the confines of the visible spectrum, the color of the light transmitted
by the solution will be the same no matter how much the concentration be
varied. This is well illustrated by solutions of the salts of neodymium and
praseodymium.

When the boundary of an absorption band is a straight line inclined to
the axis of wave-lengths it may be inferred that the limit of the band will be
displaced in proportion to the change of concentration, and that the factor of
proportionality depends upon the angle which the line makes with the axis of
abscissae. This is exemplified in fig. 45, plate 12, by the portions of the
band, at wave-length 0.47,". corresponding to the thicker layers of liquid.

In like manner, the general relation between the displacements of the
limits of absorption and the associated changes in concentration may be
easily inferred when the confines of the absorption bands are curved either
convex or concave.

EXPLANATION OF THE TABLES.

Two plans suggest themselves for the sequence of the experimental data,
viz : {a) To classify the material on the basis of the characteristics of the
absorption spectra, i. e., the succession, intensity, etc., of the bands and
regions of absorption ; (d) to arrange the results according to the chemical

r/ r — fv^

1 8 ATLAS OF ABSORPTION SPECTRA.

nature of the absorbing media. Because the first method conforms more
closel}^ to the professed object of the present research than the second, every
scheme consistent with it was tried which suggested itself. The great num-
ber of combinations on the negatives of the effects of weak, general absorp-
tion with definite, intense bands, combined with more or less uncertaint}' as
to the interpretation of the negatives in the region for which the source of
the discontinuous spectrum had to be used, made it impossible to find a
satisfactory permutation of the photographic records. Consequently the
second plan suggested above was followed as far as the text is concerned.
The spectrograms, on the contrary, are arranged, as far as possible, so as
not to have widely different absorption spectra succeed one another on the
same plate.* The organic coloring matters succeed one another in the same
order as is given to them in the English translation by A. G. Green of a
book by G. Schultz and P. Julius entitled "A Systematic Survey of the
Organic Colouring Matters" (Macmillan & Co., London, 1904). This con-
nection between the contents of the volume just named and the material
recorded below has the advantage of making it easy to find out many things
about the dyes which can not be appropriately given here, such as the names
of their discoverers, their literature, patents, methods of preparation, their
behavior with various reagents, chemical constitution, etc.

The descriptive tables following this explanatory section present the
experimental results in the following order:

(i) The absorption of a small number of interesting intermediate prod-
ucts, so-called, arranged according to the alphabetical order of their names.

(2) The absorption of such dyes as were studied and were capable of
identification with the dyes discussed in the book by Schultz & Julius.

(3) The absorption of such dyes as were not unquestionably the same
as any given in the reference volume. The accounts of these dyes follow
the alphabetical order of their comvicrcial names.

(4) The absorption of certain miscellaneous objects of more or less
interest, in alphabetical order.

Whenever a number without qualification is given to a substance it
refers to the present account, but when a number is quoted from the volume
by Schultz & Julius attention is called to the fact by the abbreviation S. & J.

In the brief account of any one dye the details are presented in the
sequence explained by the following sentences:

First. The arbitrary number of the substance in the present list is given.

Second. The commercial name of each substance is recorded precisely
as it was labeled by the firm which furnished the coloring matter. When

*Plate 2 is an exception to this statement.

RESULTS. 19

two firms sent the same dye under the same or under different names the
circumstance is explicitl}' presented.

Third. Immediately after the commercial name that of the factory is
given. The dyes were obtained from three sources. Both the Actiengesell-
schaft fiir Anilinfabrikation and Meister, Lucius & Briining presented a large
number of d3^es of their manufacture to the Johns Hopkins University. The
other d3'es were purchased from the firm of Eimer & Amend, New York.

The following abbreviations are used throughout.

[A.] Actiengesellschaft fiir Anilinfabrikation, Berlin (The Berlin Aniline Co.).

[A. A.C.] The Albany Aniline Color Works, Albany, New York.

[B.] Badische Anilin-und Sodafabrik, Ludwigshafen am Rhein (The Baden Co.).

[By.] Farbenfabriken vorm. Fr. Bayer & Co., Elberfeld (The Bayer Co.).

[C] Leopold Cassella & Co., Frankfurt am Main.

[D.] Dahl &Co., Barmen.

[D. H.] L,. Durand, Huguenin & Co., Basle and Huningen.

[G.] J. R. Geigy, Basle.

[I. ] Soci6t6 pour 1' Industrie Chimique (formerly Bindschedler & Busch), Basle.

[K.] Kalle & Co., Biebrich am Rhein.

[M.] Farbwerke vorm. Meister, L,ucius & Briining, Hochst am Main (Meister,

Lucius & Briining, Limited).
[O.] K. Oehler, Offenbach am Main.
[P.] Societe Anonyme des Matieres Colorantes de St. Denis, Paris.

Fourth. The chemical name of the absorbing medium is given.

Fifth. Reference is made either to the figure (or figures) and plate
which belong to the substance under discussion itself or to a figure which is
very much like the spectrograms of the dye considered.

Sixth. When possible, the number of the dye or the page of the inter-
mediate product, as found in the volume of Schultz & Julius, is recorded.

Seventh. The color and superficial character of the dry coloring matter
is suggested.

Eighth. The color of the solution as observed in a test-tube is followed
by the color in the cell. The change of color with thickness is often
significant.

Ninth. Then follows the concentration in grams of dry solvend in a
liter of solvent. The term "saturated" is to be understood in its general,
practical sense and not in the almost unattainable, theoretical sense.
Parenthetical, qualifying words, such as "(heated, filtered)," call attention
to the fact that the substance does not dissolve readily in water, or that the
solution contained gritt3% foreign material, etc.

Tenth. Next is given the angle between the quartz plates forming the
top and bottom of the various cells used. In the same line the numbers
denote in order the minimum and maximum depths of solution through
which the light passed before acting upon the outer limits of the negative.
The intermediate thicknesses va.Ty linearly, of course. The same angle is not

20 ATLAS OF ABSORPTION SPECTRA.

always associated with the same maximum depth, even when the minimum
thickness is unchanged, because several cells of different dimensions were
employed.

Eleventh. Finally, a brief account of the most noticeable characteristics
of the absorption spectrum, between the limits o. 20//. and 0.63//, is furnished.

The results of eye-observations of the absorption spectra come first and
serve as checks on the photographic records. The data obtained visually
are qualitatively reliable for all strong bands between 0.40// and 0.63//. For
cases of very weak, general absorption much less importance must be
ascribed to the visual results because, unfortunately, the cells were not con-
structed so as to present side by side, in the field of view, two spectra, the
one of the light after passing through the absorbing solution, the other of
the unabsorbcd light direct from the Nernst glower.

When the solution is fluorescent, or decomposes when ultra-violet light
falls u])on it, or possesses a characteristic odor, etc., the facts are noted.
That the spectrograms are not distorted by the presence of fluorescent light,
but give as true records of the absorption spectra of fluorescent compounds
as they do for non-fluorescent solutions, was ascertained by direct experi-
ments. (In particular, sec the record for solution No. 107.)

Lastly, the approximate wave-lengths of the maxima and minima of
absorption, as obtained from the spectrograms, are given, beginning near
o. 20/'. and continuing to 0.63//. When the wave-lengths of the "ends" of a
region of absorption are given they obviously have significance only under
the conditions of thickness of absorbing layer, of concentration, of length
of photographic exposure, etc., which prevailed at the time when the
spectrogram was taken. The maxima are not subject to the same limita-
tions. The fact that the Seed films can produce spurious absorption bands
in the green must be again emphasized. {See figure 102, plate 26.)

When the end of the spectrogram, which marks the fading away of the
sensitiveness of the emulsion from the yellow to the orange, is practically a
straight line perpendicular to the length of the spectrogram it means that
there is no appreciable general absorption in this locality, but when the limit
just specified is approximately a right line inclined at an obtuse angle to the
positive direction of the axis of wave-lengths it signifies that appreciable
general absorption is present in this region.

TABULATED DATA OF ABSORPTION.

Intermediate Products.

1. Amidonaphthoklisulphonic Acid IT. (M.)

Fig. I, pi. I ; pp. 57 and 58, S. & J.

Grayish-white himps. In solution
brownish yellow, colorless.

Saturated.

Angle 27.3'. Depth o to 0.25 mm.

No visible absorption. Intense blue
fluorescence. Ultra-violet absorp-
tion ends about 0.347/x.

2. y3-Naphtholdisulphonic Acid G. (M.)

F'igs. 2 and 5, pi. i ; p. 51, S. & J.

Pinkish-white powder. In solution
colorless.

Saturated.

Angle 27.3'. Depth o to 0.25 mm.

No visible absorption. Intense blue
fluorescence. Ab.sorption ends very
definitely and follows appro.ximately
a straight line from 0.346/i to 0.356/^.
Fig. 5 shows absorption exhibited by
a solution made by diluting a certain
volume of the saturated solution to
eight times its original value.
3. /'-Nitraniline. (Powder, "extra.") (M.)

Page 12, S. & J.

Lemon-yellow powder. In solution yel-
low, faint yellow.

Saturated.

Angle 37.1'. Depth o to 0.34 mm.

No visible absorption is produced by
a column 6 cm. deep. Entire ultra-
violet absorption is weak. A region
of slight absorption from 0.20/A to
0.255/n is followed by transparency
as far aso.34/u. Faint absorption
extends from 0.34/A to 0.40/x. From
o.40;u. to o.6^fi no absorption is no-
ticeable.

4. o-Nitrobenzaldehyde. (M.)

Page 61, S. & J.

White needles. In solution colorless.

Saturated.

Angle 31.2'. Depth o to 0.29 mm.

Extremely weak absorption from 0.20^

to 0.24/X. Transparent from 0.24;^ to

0.6311..

5. />-Nitrosodimethylaniline.

Fig. 3, pi. I ; p. 32, S. & J.

Dark-green, crystalline powder. In
solution brownish yellow, clear yel-
low.

Saturated.

Angle 23.4'. Depth o to 0.21 mm.

5. /i-Nitrosodimethylaniline — Continued.

Strong absorption in violet and blue
increasing towards the ultra-violet.
A remarkably transparent region
extends from 0.30/n to 0.375/4. All
the strong lines between 0.324/* and
0.363/1 are transmitted with almost
no decrease in intensity.* A very
round band stretches from 0.375/1 to
0.448/i with its ma.ximum at 0.432/i.
Complete transparency from 0.49/t
to 0.63/i.

6. Resorcine (techn. pure). (M.)

Fig. 4, pi. I ; p. 45, S. & J.

White, crystalline lumps. In solution
colorless.

Nearly saturated.

Angle 29.3'. Depth o to 0.27 mm.

No visible absorption. Very faint yel-
low in a layer a decimeter thick. Ab-
sorption ends very abruptly and
shows an almost vertical right line
determined by 0.287/1 and 0.293/4.

Coloring Matters.

7. Naphthol Yellow. (A.) Naphthol Yellow

S. (M.) Sodium salt of dinitro-a-
naphthol-;8-monosulphonic acid.

Fig. 42, pi. 11; No. 4, S. & J.

Orange-yellow powder. In solution
brownish yellow, pure yellow.

Saturated (heated).

Angle 31.2'. Depth o to 0.29 mm.

Intense band in violet, ultra-violet side
invisible. Absorption decreases from
0.20/1 towards 0.335/t. Transparent
region around 0.335/4. A pair of
overlapping bands extends from
about 0.345/t to 0.465/4. Their max-
imum absorption is at 0.385/4 and
their least absorption is at 0.4 1/4.
Very transparent from 0.465/1 to be-
yond 0.63/t.

8. Aurantia. Ammonium salt of hexanitro-

diphenylamine.

Fi?- 39' pl- 10; No. 6, S. & J.

Reddish-brown crystals. In solution
dull red, yellow.

10 g. per liter (filtered).

Angle 42.5'. Depth o to 0.36 mm.

General absorption in violet. Absorp-
tion decreases from o.20/t towards
0.28/4. Transparent region from
0.28/1 to 0.33/1. Wide band from
0.33/4 to 0.49/4 with its ma.ximum

« R. W. Wood. •' On Screens Transparent only to Ultra-Violet Light and their use in Spectrum Photography."
Phil. Mag., V. 5, Feb., 1903, pp. 257-263.

22

ATLAS OF ABSORPTION SPECTRA.

8. Aurantia — Continued.

at 0.4I/A. As the concentration in-
creases the absorption encroaches
much faster on the transparent re-
gion in the ultra-violet than on the
limit in the yellow. Very trans-
parent to yellow and orange.

9. Fast Yellow. (B.) Sodium salt of

amidoazotoluene-disulphonic acid.

Somewhat similar to fig. 40, pi. 10;
No. 9, S. & J.

Brownish-yellow powder. In solution
brownish yellow, yellow.

15 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Absorption in violet and blue. The
region of partial transmission in
the ultra-violet is not as complete
for solution No. 9 as for solution
No. 32. Also the boundaries of the
violet band are somewhat more defi-
nite for the former solution than
for the latter. The less refrangible
side of this band is more like the
corresponding region for solution
No. 129, fig. 13, pi. 3. Absorption
decreases gradually from o.20/i, to
semi-transparency at about 0.34/1. A
wide, diiifuse band extends from this
region to about 0.475/*. Its maxi-
mum is at 0.40/1. Transparent from
o.475/t to 0.63/*.
10. Orange G. (A.) Sodium salt of benzene-
azo-jff-naphthol-disulphonic acid G.

Fig. 30, pi. 8; No. 14, S. & J.

Yellowish-red powder. In solution
red, yellow.

Saturated (heated).

Angle 21.3'. Depth o to 0.18 mm.

Strong absorption in blue and green.
Sharp on yellow edge. Two ultra-
violet bands meet at about 0.29/* in
a semi-transparent spot. The maxi-
mum of the less refrangible band is
0.325/t. This strong band meets a
very weak one at 0.365/*. The center
of the weak band is 0.39/t. The
weak band joins an intense one at
o.42/<,. This last band joins a still
stronger band, from which it is not
resolved, at 0.485/1. The maximum
of the stronger band is at 0.505/1.
Absorption ceases at 0.53/t. Com-
plete transparency to 0.63/t.

II. Ponceau 2 G. (M.) Sodium salt of
benzene -azo-/?-naphthol - disulphonic
acid R.

11. Ponceau 2 G — Continued.

Fig. 6, pi. 2; No. 15, S. & J.

Bright-red powder. In solution yel-
lowish red, yellow.

7 g. per liter (filtered).

Angle 27.3'. Depth o to 0.25 mm.

Comparatively weak band in the blue-
green, with a shadowy, fainter com-
panion on the yellow side. Absorp-
tion decreases gradually from o.20/t
to 0.34/1. The nearly transparent
region from 0.34/1 to 0.44/* is inter-
rupted by a very faint band having
its maximum at 0.39/1. The pair of
stronger bands extends from 0.44/1
to 0.545/1. Transparent from 0.545/1
to 0.63/1. Same empirical formula
as No. 10. No. 10 is derived from
the G acid, while No. 11 is a salt
of the R acid.

12. Chrysoidine. Hydrochloride of diami-

doazobenzene.

Fig. 7, pi. 2 ; No. 17, S. & J.

Reddish-brown powder. In solution
brown, yellow.

10 g. per liter (filtered).

Angle 23.4'. Depth o to 0.21 mm.

Absorption in violet, blue, and green
with maximum in the indigo. Ab-
sorption decreases from 0.20/1 to
0.33/t. Transparent from 0.33/t to
0.36/1. A pair of broad, unseparated
bands absorbs from 0.36/1 to 0.54/t.
The band of greater refrangibility
is the more intense and has its max-
imum at 0.43/t. Transparent from
0.54/1 to 0.63/1. The less refrangible
band disappears first on dilution. A
five-strip negative shows that the
outer boundaries of the pair of bands
are steep and definite.
13. Chromotrope 6 B. (M.) Sodium salt
of />-acetamidobenzene-azo- 1 :8-dioxy-
naphthalene disulphonic acid.

Fig. 8, pi. 2; No. 38, S. & J.

Grayish-brown powder. In solution
red, pink.

5.71 g. per liter.

Angle II. 7'. Depth o to o.ii mm.

Strong absorption in green-yellow.
Transparent from 0.35/1 to 0.465/t.
A strong band has its beginning at
0.465/i and its maximum at 0.515/t.
The less refrangible side joins a weak
companion band extending into the
orange and red. More dilute solu-
tions show that the intense band is
symmetrical with respect to its max-

COLORING MATTERS.

23

13. Chromotrope 6 B — Continued.

imum until it joins the associated
band. More concentrated solutions
show very distinctly the weaker
band in the orange-red.

14. Azo Coccine 2 R. (A.) Sodium salt

o f xy lene-azo-a-naphthol-/'-sulphonic

acid.
Fig. 9, pi. 2 ; No. 50, S. & J.
Reddish-brown powder. In solution

salmon pink, salmon pink.
Saturated (heated).
Angle 27.3'. Depth o to 0.25 mm.
Narrow band in the blue-green. An

absorption band of very indefinite

edges extends from about 0.48/* to

o.53ft with its maximum at 0.505^.

Transparent from o.^^/x to 0.63/i.

15. Brilliant Orange G. (M.) Sodium salt

of xylene-azo-/8-naphthol-mono - sul-
plionic acid.

Fig. 31, pi. 8;No. 54, S. & J.

Cinnabar-red powder. In solution
yellowish red, deep yellow.

7 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Intense absorption in blue-green and
blue. Very sharp on the yellow side.
Absorption decreases from 0.20/i, to
weak absorption at 0.295/*, then in-
creases to maximum absorption at
0.32/1. At o.355/t semi-transparency
obtains. A definite band has its
maximum at 0.395/1 and joins the
next band at 0.43/*. The next band
has its maximum at 0.48/1 and joins
the adjacent band at 0.505/1. The
final band" has a maximum at 0.52/1.
Absorption ends at 0.545/1. Com-
plete transparency to 0.63/1. The
band at 0.395/1 disappears rapidly
with dilution. Same empirical
formula as solution No. 14.

16. Ponceau 2 R. (A.), (M.) Sodium salt

of xylene-azo-/?-naphthol-disulphonic
acid.

Similar to fig 55, pi. 14 ; No. 55, S. & J.

Brownish-red powder. In solution red,
pink.

5 g. per liter (heated).

Angle 27.3'. Depth o to 0.25 mm.

Hazy-edged band in the blue-green.
Similar absorption to that of solu-
tion No. 17 in the ultra-violet and
identical with it in the visible region.

17. Ponceau 3 R. (A.), (M.) Sodium salt

of i/i-cumene-azo - j3 - naphthol-disul-
phonic acid.

17. Ponceau 3 R — Continued.

Fig. 55, pi. 14; No. 56, S. & J.

Dark-red powder. In solution red, pink.

5 g. per liter (heated).

Angle 29.3'. Depth o to 0.27 mm.

An absorption band is in the blue-
green. It has its maximum at 0.50/1
and extends from about 0.47/1 to
0.54/1. Transparent from 0.54/1 to
0.63/1.

18. Crystal Ponceau 6 R. (A.), (M.)

Sodium salt of a-naphthalene-azo-
/3-naphthol-disulphonic acid.

Similar to fig. 55, pi. 14; No. 64, S. & J.

Brownish-red crystals with golden re-
flex. In solution light red, pink.

5 g. per liter (heated).

Angle 27.3'. Depth o to 0.25 mm.

Hazy-edged band in the blue-green and
green. Similar absorption to that of
solution No. 17. The ultra-violet ab-
sorption, however, is somewhat more
intense and extends to greater wave-
lengths for solution No. 18 than for
solution No. 17. The visible band
extends from 0.465/1 to 0.56/1 with
its maximum at 0.5 i/i.

19. Bordeaux B. (M.) Sodium salt of o-

naphthalene-azo - /3 - naphthol-disul-
phonic acid.

Similar to fig. 19, pi. 5 ; No. 65, S. & J.

Brown powder. In solution red, red.

4.18 g. per liter.

Angle 42.5'. Depth o to 0.36 mm.

Hazy-edged band in the green. The
sides of the band in the green and
the orange end of the spectrogram
slope a little more for solution No.
19 than for No. 106. Band from
0.485/1 to 0.545/1, with maximum at
0.515/1. The least refrangible ends
for all the spectrograms slope, thus
showing that there is some general
absorption in the orange. More con-
centrated solutions show that the
greatest transparency occurs at
0.414/1. Same empirical formula as
No. 18.

20. Coccinine B. (M.) Sodium salt of p-

methoxy- toluene - azo - p - naphthol-
disulphonic acid.

Similar to fig. 55, pi. 14; No. y^, S. & J.

Dark-red powder. In solution bright-
red, red.

13.64 g. per liter.

Angle 12.8'. Depth o to o.ii mm.

.Strong absorption in green-yellow.
Similar to solution No. 17, save that

24

ATLAS OF ABSORPTION SPECTRA.

20. Coccinine B — Continued.

a weak absorption band seems to
have the limits 0.315JL1 and 0.355/x,
with a maximum at 0.33/i. Intense
band from 0.465^ to 0.555/u, with a
maximum at o.5iOfi. Transparent
from 0.555/i to 0.63/i. Very concen-
trated solutions or deeper layers
show that the transparent region on
both sides of 0.4111 becomes opaque
much faster than the orange and red
region. Red is transmitted when all
shorter wave-lengths are absorbed
completely. The solution exhibits
strong dispersive power.

21. Eosamine B. (A.) Sodium salt of p-

cresol - methyl -ether-azo-a-naphthol-
disulphonic acid.

Fig. 52, pi. 13; No. 74, S. & J.

Reddish-brown powder. In solution
yellowish red, pink.

8.89 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Strong band in blue-green and green.
Intense, round band from 0.465/1 to
0.565(11, with its maximum at about
0.52/i. Transparent from 0.565/1 to
0.63/1. Same empirical formula as
No. 20.

22. Erika B. (A.) Sodium salt of methyl-

benzenyl - amido - thio-xylenol-azo-a-
naphthol-disulphonic acid.

Fig. 57. pl-i5;No.78, S. &J.

Reddish-brown powder. In solution
red, pink.

6.67 g. per liter.

Angle 19.5'. Depth o to 0.18 mm.

Strong absorption in blue, green, and
green-yellow. Two unresolved bands
absorb strongly from 0.46/1 to 0.59/t.
The more refrangible band shows
greater intensity than its companion
and has its maximum at 0.52/1. Slight
absorption in the orange is followed
by greater transparency in the red.

23. Emin Red. (A.) Sodium salt of methyl-

benzenyl - amido - thioxylenol-azo-/?-

naphthol-sulphonic acid.
Fig. 29, pi. 8 ; No. 80, S. & J.
Red powder. In solution red, pink.
Saturated (heated).
Angle 31.2'. Depth o to 0.29 mm.
Weak, hazy absorption in blue and

green. Strong absorption from o.20/<.

to about 0.35/1, then a rather rapid

decrease in absorption sets in. From

23. Emin Red — Continued.

0.38/t to 0.45/1 a semi-transparent re-
gion exists. A round band extends
from 0.45/1 to 0.54/1. Its maximum
is near 0.495/1. The less refrangible
side of this band is far more definite
than its ultra-violet edge. Trans-
parent from 0.54/1 to 0.63/1.

24. Janus Green. (M.) Chloride of safra-

nine-azo-dimethylaniline.

No. 81, S. & J.

Olive-green, crystalline powder. In so-
lution blue, blue.

4.6 g. per liter.

Angle 17.0'. Depth o to 0.14 mm.

Band in orange and orange-red. Trans-
parent to pure red. Very general ab-
sorption in ultra-violet, decreasing
gradually from o.20/t to 0.40/1. Trans-
parent from 0.40/1 to 0.515/1. The
absorption band begins at 0.515/1.

25. Tropffioline O. (C.) Sodium salt of p-

sulphobenzene-azo-resorcinol.

Similar to fig. 37, pi. 10 ; No. 84, S. & J.

Brown powder. In solution wine-color,
yellow.

Saturated (heated).

Angle 25.5'. Depth o to 0.21 mm.

Faint absorption in the violet. Similar
absorption to that of solution No. 81.
Weak absorption from 0.20/1 to
0.275/1. Transparent from 0.275/1 to
0.325/1. A weak, hazy band extends
from 0.325/1 to 0.41/1 with its maxi-
mum around 0.37/1. Transparent
from 0.41/1 to 0.63/1.

26. Tropreoline OOO No. i. Sodium salt of

/i-sulphobenzene-azo-a-naphthol.

Similar to fig. 31, pi. 8; No. 85, S. & J.

Reddish-brown powder. In solution
red, salmon pink.

6.67 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Absorption in violet, blue, and green.
Similar absorption to that of solu-
tion No. 15. Rather strong absorp-
tion continues from 0.20/1 to about
0.33/1 and then decreases rapidly to
semi-transparency. A tolerably trans-
parent region is from 0.35/1 to 0.37/1.
Three unresolved bands with maxima
at about 0.41/1, 0.48/1, and 0.52/1 fol-
low. The intermediate points of less
intensity of absi.irption are 0.435/t
and 0.450/1. At 0.545/1 the absorption
cea.ses. Transparent from 0.545/1 to
0.63/1.

COLORING MATTERS.

25

27. Tropxnline OOO No. 2. Sodium salt of

/>-sulphobenzeiie-azo-/3-naphthol.

No. 86, S. & J.

Bright, orange powder. In solution
deep red, salmon pink.

14 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Msible absorption and spectrogram
identical with No. 26. Similar ab-
sorption to that of solution No. 15.
Nos. 26 and 27 have the same em-
pirical formulae, but differ by a and /?
in the naphthol.

28. Methyl Orange III. (P.) Sodium salt

of' /»-sulphobenzene-azo - dimethylani-

line.
Fig. 41, pi. 11; No. 87, S. & J.
Ocher-yellow powder. In solution red,

yellow.
Saturated (heated).
Angle 27.3'. Depth o to 0.25 mm.
Absorption in blue and green. A strong

band extends from 0.36/i to 0.525^1.

This band is very round with its

maximum at 0.44/x. Transparent

from 0.525/^ to 0.63/u..

29. Tropc-eoHne 00. (C.) Sodium salt of

^-sulphobenzene-azo - diphenylamine.
Similar to fig. 40, pi. 10 ; No. 88, S. & J.
Yellow powder. In solution yellowish

red, yellow.
6 g. per liter (heated and filtered).
Angle 25.5'. Depth o to 0.21 mm.
Delicate absorption in violet and blue.
Similar absorption to that of solu-
tion No. 32. The extreme ultra-
violet absorption is weak because the
lines near 0.23/^ show on all three
photographic strips. From 0.385^ to
0.47/i a weak absorption band obtains
with its maximum at 0.43/x. The
substance is very transparent to yel-
low and red. Nos. 29 and 32 have
the same empirical formulae. No. 29
is the para-compound and No. 32 is
the meta-. No. 29 shows weaker
absorption than No. 32.
30. Curcumeine. (A.) Mixture of nitrated
diphenylamine yellow with nitrodi-
phenylamine.
Fig. 12, pi. 3; No. 91, S. & J.
Ocher-yellow powder. In solution red,

yellow.
Saturated (heated).
Angle 27.3'. Depth o to 0.25 mm.

30. Curcumeine — Continued.

Absorption in violet, blue, and blue-
green. Absorption complete at o.20/t,
decreasing very gradually with com-
paratively definite contour to o.455/t.
Transparent from 0.455/x to 0.63^*.
31.AZO Acid Yellow. (A.) Azo Yellow,
concentrated. (M.) Mixture of
nitrated diphenylamine yellow with
nitro-diphenylamine.
Similar to fig. 12, pi. 3 ; No. 92, S. & J.
Ocher-yellow powder. In solution

brownish yellow, yellow.
Saturated (heated).
Angle 27.3'. Depth o to 0.25 mm.
Strong absorption of violet, blue, and
blue-green. Similar absorption to
that of solution No. 30. Absorption
is nearly complete and uniform from
0.20/J. to about 0.39/i. Then the ab-
sorption decreases in a gently slop-
ing curve to about 0.505/*. Trans-
parent to yellow and red. Nos. 30
and 31 are mixtures of the same con-
stituents and have very similar re-
gions of absorption.
32. Metanil Yellow. (A.) Sodium salt of
w - sulphobenzenc-azo-diphenylamine.
Fig. 40, pi. 10; No. 95, S. & J.
Brownish-yellow powder. In solution

yellowish red, yellow.
4.29 g. per liter (filtered),
^ngle 23.4'. Depth o to 0.21 mm.
Absorption in violet and blue. A band
with very indefinite boundary ex-
tends from about 0.36/x to 0.47/u.. The
maximum is near 0.41JU,. Transparent
to yellow and red. A very concen-
trated solution shows complete ab-
sorption from 0.20/A to 0.5 ijn with a
semi-transparent spot at 0.34^'' and
maximum absorption at 0.40/i. Ab-
sorption ceases abruptly at 0.535/x.
33. Naphthylamine Brown. Sodium salt of
p - sulphonaphthalene-azo-a-naphthol.
Similar to fig. 11, pi. 3 ; No. loi, S. & J.
Brown powder. In solution reddish

brown, almost colorless.
I I.I I g. per liter (heated and filtered).
Angle"30.o'. Depth o to 0.45 mm.
Very weak, general, indefinite absorp-
tion for all visible colors of shorter
wave-lengtlis than the yellow. Sim-
ilar absorption to that of solution
No. 47. Absorption was nearly com-
plete from 0.20/X to o.274;n. From

26

ATLAS OF ABSORPTION SPECTRA.

33. Naphtliylamine Brown — Continued.

the latter wave-length the absorption
decreased very gradually to a maxi-
mum of semi-transparency at about
o.43/t. The apparent absorption at
o.52yti is much exaggerated by the
lack of relative sensitiveness of the
photographic film at this spot. Very
slight absorption from o.55yti to 0.63/*.
A weaker solution presented only
ultra-violet absorption.

34. Fast Red A. (A.) New Coccine O.

(M.) Sodium salt of /i-sulphonaph-
thalene-azo-y8-naphthol.

Fig. 27, pi. 7; No. 102, S. & J.

Brownish-red powder. In solution red,
pink.

5 g. per liter (heated).

Angle 27.3'. Depth o to 0.25 mm.

Hazy absorption in blue-green and
general absorption in blue. Muddy-
looking solution. Two partially re-
solved bands extend from 0.41 5/^ to
0.54/t with maxima of absorption at
about 0.45/x and 0.50S/X. The less
refrangible band is the more intense.
Orange and red are transmitted, but
the sloping end of the photograph
shows that slight, general absorption
is present in orange. Nos. 33 and 34
have the same empirical formula.
They differ by a and (3 naphthol.

35. Azo Rubine S. (A.) Sodium salt of

/"-sulphonaphthalene - azo-a-naphthol-
/'-sulphonic acid.

Similar to fig. 55, pi. 14; No. 103,
S.&J.

Brown powder. In solution red, pink.

10 g. per liter.

Angle 19.5'. Depth o to 0.18 mm.

Absorption in green. Much like solu-
tion No. 17 with slight differences in
the ultra-violet. Absorption decreases
from o.20fi to 0.27/1. The strong lines
at 0.255/X and 0.275/x are transmitted
by the deepest layer. Absorption in-
creases from o.27;u to a maximum at
0.315/i. Then the absorption de-
creases to approximate transparency
at o.36ja. Transparent from 0.36/^ to
o.465;it. Strong band from 0.465/a to
0-55.S/^ with maximum at 0.51/11. The
visible band is in the same place as
the like band of No. 20, but the
ultra-violet is different. Transparent
to orange and red.

36. Fast Red, extra. (A.) Sodium salt of
/>-sulphonaphthalene-azo-^-naphthol-
monosulphonic acid.

Similar to fig. 55, pi. 14; No. 105,
S.&J.

Reddish-brown powder. In solution
red, pink.

7 g. per liter.

Angle 27.3'. Depth o to 0.25 mm.

Absorption in blue-green and green.
Absorption the same throughout as
for No. 35 except the position of
the visible band. No. 36 absorbs
from 0.460/t to o.545;a with the max-
imum at 0.505^1. Same empirical
formula as for No. 35.

^y. New Coccine. (A.) Sodium salt of
/'-sulphonaphthalene-azo-;8-naphthol-
disulphonic acid.

Similar to fig. 52, pi. 13 ; No. 106,
S.&J.

Scarlet-red powder. In solution yel-
lowish red, pink.

10 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Absorption in blue-green and green.
Similar absorption to that of solu-
tion No. 21. The ultra-violet absorp-
tion of solution No. 37 seems to con-
sist only of one band whereas that
of solution No. 21 seems to be separ-
ated into two bands by a minimum of
absorption near 0.274/11. Absorption
decreases from o.20;u, to transparency
about 0.37^. A strong, round band
from 0.445/i to 0.56/11 has its maxi-
mum at 0.5 i/u. Transparent from
0.56/a to 0.63/u.

38. Fast Brown 3 B. (A.) Sodium salt of
sulphonaphthalene-azo-a-naphthol.

Similar to fig. 23, pi. 6 ; No. 1 1 1, S. & J.

Dark-brown, glistening powder. In so-
lution reddish brown, faint brown.

15 g. per liter.

Angle 2^.^'. Depth o to 0.25 mm.

Absorption most intense in blue-green
and green with slight general absorp-
tion on both sides. Similar absorp-
tion to that of solution No. 60. A
fairly strong band from 0.46/u to
0.54/u, has its maximum at 0.51/1. No
definite band from 0.54/n to 0.63/u, but
general absorption is made evident
by the slope of the end of the nega-
tive.

COLORING MATTERS.

27

39. Mordant Yellow O. (M.) Sodium salt of

siilphonaphthalene-azo-salicylic acid.

Similar to fig. 13, pi. 3 ; No. 1 16, S. & J.

Yellow powder. In solution reddish
yellow, yellow.

10 g. per liter.

Angle 31.2'. Depth o to 0.29 mm.

Absorption in the violet only. Similar
absorption to that of solution No.
129. Strong absorption from o.20/t
to 0.28/4. Slight weakening of ab-
sorption from 0.28/1 to 0.34/i. Ab-
sorption attains a maximum at 0.36/1
and then slopes gradually, with a
comparatively definite edge, to trans-
parency at 0.44/1. From this point
to 0.63/1 complete transparency ex-
ists.

40. Dianil Yellow R. (M.)

Similar to fig. 37, pi. 10; No. 124,
S. & J.

Orange-yellow powder. In solution
clear yellow, yellow.

Saturated.

Angle 31.2'. Depth o to 0.29 mm.

Faint absorption in violet. Similar ab-
sorption to that of solution No. 81.
Absorption is comparatively strong
at 0.20/1 and decreases to partial
' transparency near 0.295/*. A toler-
ably weak band extends from this
region to about 0.435/1. Its maximum
is indeterminate. Transparent from
0.44/t to 0.63/t.
4i.Resorcine Brown. (A.) Sodium salt of
xylene - azo - resorcin-azo-benzene-/»-
sulphonic acid.

Fig. 38, pi. 10; No. 137, S. & J.

Brown powder. In solution brown,
yellow.

7.78 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Strong absorption in the violet and
blue. A more concentrated solution
exhibited absorption in the green
and yellow. A long band or region
of absorption extends from 0.35/1 to
0.52/1. The maximum is near 0.395/t.
There is a slight minimum of absorp-
tion at 0.48/1. The presence of a
weaker, less refrangible band, in-
creasing in intensity at 0.48/*, is more
marked as the concentration is in-
creased. More concentrated solutions
show that the transparency in the
ultra - violet rapidly disappears.

41. Resorcine Brown — Continued.

whereas the bands do not encroach
as rapidly on the yellow. Trans-
parent from 0.53/1 to 0.63/1. The
absorption of the concentrated solu-
tions is like that of solution No. yy,
fig- 35-

42. Acid Brown. (D.) Sodium salt of bi-

sulphobenzene-disazo-a-naphthol.

Similar to fig. 39, pi. 10; No. 138,
S. & J.

Brown powder. In solution brown,
yellow.

7.5 g. per liter.

Angle 25.5'. Depth o to 0.21 mm.

Absorption in violet and blue. Similar
absorption to that of solution No. 8.
Very weak absorption from o.20/t
to 0.29/t. Transparent to continuous
background of spark from 0.29/1 to
0.33/1. Weak, indefinite absorption
band from 0.33/1 to 0.48/1, with max-
imum indeterminate. Transparent to
yellow, orange, and red.

43. Ponceau B O, extra. (A.) Sodium salt

of benzene-azo-benzene-azo - j8- naph-
thol-disulphonic acid.

Similar to fig. 52, pi. 13 ; No. 146,
S. & J.

Light-brown powder. In solution yel-
lowish red, pink.

7 g. per liter.

Angle 21.5'. Depth o to 0.20 mm.

Strong absorption in blue and green.
Similar absorption to that of solu-
tion No. 21. Absorption decreases
from o.20/t to 0.295/1, and then in-
creases to a maximum near 0.345/1.
This band fades to semi-transparency
about 0.4/t. The width and general
appearance of the region of separa-
tion between the ultra-violet bands
and the band in the green resembles
much more closely the correspond-
ing region for solution No. 48 than
for solution No. 21. Transparency
continues from 0.4/1 to 0.44/1., where a
strong, round band begins. The last
band ends at 0.565/t. Its maximum is
at 0.51/1. Transparent from 0.565/1
to 0.63/1. Absorption from this band
moves more rapidly towards the
ultra-violet than towards the red,
with increasing concentration. Same
empirical formula as No. 42.

28

ATLAS OF ABSORPTION SPECTRA.

44. Janus Red B. (M.) Chloride of tri-

methyl-amido- benzene - azo - in - tol-
uene-azo-;8-naphthol.

Similar to fig. 23, pi. 6 ; No. 149, S. & J.

Reddish-brown powder. In solution
yellowish red, faint yellowish red.

Saturated.

Angle 54.6'. Depth o to 0.50 mm.

Pointed, V-shaped, weak band in the
blue-green. Similar absorption to
that of solution No. 60. Absorption
is strong at oaOfi and decreases
gradually and in a poorly defined
manner to transparency at 0.375/*.
The transparent region continues to
0.455/it. An absorption band lies be-
tween 0.455/n and o.540ya, with its
maximum at 0.5 i/x. Slight general
absorption in the yellow and orange,
but transparent to the red.

45. Cloth Red G. (O.) Sodium salt of

toluene - azo-toluene-azo-/?-naphthol-
monosulphonic acid.

Fig. 25, pi. 7; No. 153, S. & J.

Reddish-brown powder. In solution
red, faint pink.

8.33 g. per liter (heated and filtered).

Angle 31.2'. Depth o to 0.29 mm.

Bands in blue-green and green with
hazy edges and weak general ab-
sorption in both directions. A band
extends from o.445yu. to O-S^/x and ap-
pears to be composed of a stronger
band with a weaker, more refrangible,
unresolved companion. Their maxi-
mum of absorption is at 0.515/t. The
slant at the end of the negative shows
that weak, general absorption is ex-
erted in the orange. Transparent to
the red.

46. Cloth Red O. (M.) Sodium salt of

toluene - azo-toluene-azo-/?-naphthol-
disulphonic acid.

Fig. 21, pi. 6; No. 154, S. & J.

Dark-brown powder. In solution deep
red, very faint red.

6.36 g. per liter (warmed and filtered).

Angle 33.2'. Depth o to 0.30 mm.

Maximum of absorption in blue-green
with weak absorption in yellow and
orange. Absorption band starts at
0.485/x, attains its maximum at 0.52/1,
and is dissipated in weak general ab-
sorption about 0.555/t. The end of
the negative slants appreciably.
Transparent to red.

47. Cloth Red 3 G A. (A.) Sodium salt of

toluene - azo-toluene-azo-;8-naphthyl-
amine-monosulphonic acid.

Fig. II, pi. 3; No. 155, S. & J.

Brownish-red powder. In solution red-
dish brown, light brown.

Saturated (heated).

Angle 1° 57'. Depth o to 1.07 mm.

General absorption in violet, also a
maximum of absorption in the blue-
green and green. Absorption is about
complete at 0.20/1 and increases very
gradually, with hazy contour, to
semi-transparency at about 0.42/*.
Semi-transparency from 0.42/i to
0.49/n. Weak band from 0.49/x to
0.54/i. Transparent from 0.54/1 to
0.63/1.

48. Ponceau 4 R B. (A.) Sodium salt of

sulphobenzene - azo - benzene - a.zo-/i-
najihthol-monosulphonic acid.

Fig. 51, pi. 13; No. ifio, .S. & J.

Reddish-brown powder. In solution
yellowish red, pink.

10 g. per liter (heated).

Angle 19.5'- Depth o to 0.18 mm.

Strong absorption in blue-green and
green. At 0.455/x the strong band be-
gins and extends to 0.565/1, with its
maximum about 0.5 i/i. Transparent
from 0.565/1 to 0.63/1.

49. Biebrich Scarlet. (K.) Sodium salt of

sulphobenzene - azo - sulphobenzene -
azo-/i(-naphthol.

Similar to fig. 51, pi. 13; No. 163,
S. & J.

Reddish-brown powder. In solution
red, pink.

6 g. per liter.

Angle 19.5'. Depth o to 0.18 mm.

Absorption band in blue-green and
green. Absorption decreases from
0.20/1 to about o.32/(,, where a semi-
transparent region appears. This is
followed by an absorption band with
its maximum at 0.355/1. Slight ab-
sorption from 0.39/1 to 0.45/t. A defi-
nite band starts at 0.45/1, reaches a
maximum near 0.51/1, and ends at
0.555/x. Transparent from 0.555/1 to
0.63/1. A solution of 10 g. per liter
showed almost complete absorption
from 0.20/1 to 0.36/1. From 0.395/1 to
0.445/1 only the first photographic
strip received light. The band is very
round from 0.445/1 to its end at

COLORING MATTERS.

29

49. Bielirich Scarlet — Continued.

0.585/1. Transparent to orange and
red. Same empirical formula as No.
48 and almost identical visible ab-
sorption.

50. Wool Black. (A.) Sodium salt of sul-

pbobenzene-azo - sulphobenzene-azo-
/'-tolyl-^-naphthylaniiiie.

Figf. 67, pi. 17; No. 166, S. & J.

niuish-black powder. In solution pur-
ple, light purple.

5.56 g. per liter (filtered).

Angle 35.1'. Depth o to 0.32 mm.

Hazy band in yellow spreading indefi-
nitely into the orange. Transmits
bright red. At 0.49/1 a region of ab-
sorption commences which seems to
consist of a hazy central band with
a weak, washed-out companion on
each side. The chief maximum is
about o.54/t. Absorption is very weak
from o.6o/i to 0.63/1. A very concen-
trated solution shows that the max-
imum of transparency is near 0.44/1.

51. Ponceau 6 R B. (A.) Sodium salt of

sulphotoluene - azo - toluene - azo - /3-
naphthol-a-sulphonic acid.

Fig. 56, pi. 14; No. 169, S. & J.

Reddish-brown powder. In solution
, scarlet red, pink.

5.38 g. per liter.

Angle 31.2'. Depth o to 0.29 mm.

Strong band in the green which is
more definite on the blue side than
on the yellow border. Strong band
from 0.465/1 to 0.565/1. The maxi-
mum is at 0.5 i/i. The band is prob-
ably composed of two unresolved
bands of which the weaker lies nearer
the red. Transparent from 0.565/1 to
0.63/1.

52. Blue-Black. (B.) Sodium salt of sulpho-

/8-naphthalene - azo - a - naphthalene-
azo-/8-naphthol-disulphonic acid.

No. 186. S. & J.*

Bluish-black powder. In solution bluish
violet, violet.

6.69 g. per liter (filtered).

Angle 33.2'. Depth o to 0.30 mm.

Very indefinite absorption in green-
yellow, yellow, and orange, with
maximum in yellow. Absorption is
strong at 0.20/1 and decreases gradu-
ally to about 0.34/1. Approximately
transparent from 0.4/x to 0.5/1. Ab-
sorption starts near 0.50/r,, increases
to a maximum about 0.54/t, and de-

52. Blue-Black — Continued.

creases to weak, general absorption
from 0.58/1 to 0.63/t.

53. Anthracene Yellow C. (C.) Sodium

salt of thio-di-benzene-disazo-di-sali-
cylic acid.

Similar to fig. 37, pi. 10 ; No. 190,
S. & J. '

r>rownish-yellow powder. In solution
muddy yellowish brown, greenish
yellow.

6 g. per liter (filtered).

Angle 21.3'. Depth o to 0.18 mm.

Absorption in violet. Somewhat sim-
ilar absorption to that of solution
No. 81. However, the absorption of
solution No. 53 is more intense than
that of solution No. 81. Absorption
decreases from 0.20/1 to a semi-trans-
parent strip at about 0.295/1. Beyond
this strip a band with hazy contour
extends as far as 0.41/1 with its max-
imum at about 0.34/1. Transparent
from 0.4 i/i to 0.63/1.

54. Bismarck Brown. (A.) Hydrochloride

of benzene-disazo-phenylene-diamine.
Fig. 7, pi. 2 ; No. 197, S. & J.
Dark-brown powder. In solution brown,

yellow.
30 g. per liter (filtered).
Angle 19.5'. Depth o to 0.18 mm.
Visible and photographic ab.sorption

identical with that of solution No. 12.

55. V e s u v i n e. (B.) Hydrochloride of

toluene-disazo-Mj-tolylene-diamine.

Fig. 7, pi. 2; No. 201, S. & J.

Dark-brown powder. In solution red-
dish brown, yellow.

4.29 g. per liter.

Angle 31.2'. Depth o to 0.29 mm.

Visible and photographic absorption
identical with that of solution No. 12.

56. Congo Orange G. (A.) Sodium salt of

diphenyl - disazo-phcnetol-/3-naphthyl-
amine-disulphonic acid.

Fig'- 33, pl-9; No. 217, S. & J.

Brownish-red powder. In solution red-
dish yellow, yellow.

5.38 g. 'per liter.

Angle 23.4'. Depth o to 0.21 mm.

Hazy absorption in blue, blue-green,
and green with maximum in the
green. Tolerably strong absorption
decreases from 0.20/1 to a weak mini-
mum near 0.32/1 and then increases
to a maximum about 0.36/t. A
semi-transparent region lies between

♦Spectrogram too indefinite for reproduction.

30

ATLAS OF ABSORPTION SPECTRA.

56. Congo Orange G — Continued.

0.405(a and 0.44/1. A weak, hazy band
begins at o.44i«. and continues to
o.47Sfi. at which point it joins a
more intense band. The latter has
its maximum at 0.50S/H and then de-
creases to transparency at 0.53/*.
Transparent from 0.53/x to 0.63/1.
More concentrated solutions empha-
size all the maxima of absorption
just outlined and the minimum at
0.42/1.

57. Chrysamine G. (A.) Sodium salt of

diphenyl-disazo-bi-salicylic acid.

Similar to fig. 36, pi. 9 ; No. 220, S. & J.

Yellowish-brown powder. In solution
brownish yellow, faint yellow.

7 g. per liter (heated and filtered).

Angle 35.1'. Depth 0.26 to 0.58 mm.

No visible absorption unless, perhaps,
a faint weakening of the extreme
violet. Somewhat similar absorption
to that of the more dilute solution of
No. 77. For the layer used the ab-
.sorption is nearly complete from
o.20/t to o.2gii. The continuous back-
ground is transmitted from 0.29/1 to
0.30/1. The limit of the ultra-violet ab-
sorption is approximately a straight
line joining the wave-lengths 0.365/1
and o.395/t at the opposite edges of
the negative. Transparent from
o.395/t to 0.63/1. More dilute solu-
tions and wedges of liquid tapering
to infinitesimal thickness show that
ultra-violet absorption is very weak.
58. Cresotine Yellow G. (M.) Sodium salt
of diphenyl - disazo-bi-o-cresol - car-
boxylic acid.
Similar to fig. 36, pi. 9 : No. 221, S. & J.

Yellowish-brown powder. «Jn solution

yellow, faint yellow.
Saturated.

Angle 39.0'. Depth o to 0.36 mm.
Absorption in violet and indigo. Ab-
sorption much like that of the more
dilute solution of No. 77. The solu-
tion has a peculiar odor. A washed-
out band begins at 0.3 i/i, passes
through a maximum near 0.355/1,
and then fades away at 0.44/1. A
rather narrow region of semi-trans-
parency, the center of which is near
0.30/1, separates this band from a
weak, more refrangible ultra-violet
band. Transparent from 0.44/1 to
0.63/x.

59. C o n g o R e d. (A.) Sodium salt of
diphenyl-disazo-bi-naphthionic acid.

Similar to fig. 26, pi. 7 ; No. 240, S. & J.

Reddish-brown powder. In solution
red, yellowish red.

5.9 g. per liter.

Angle 27.3'. Depth o to 0.25 mm.

Absorption in blue, blue-green, and
green with maximum nearer the
green end. Similar absorption to that
of solution No. 69. Absorption de-
creases from o.20fjL to near 0.28/1 and
then increases to a maximum at
about 0.325/1. These two partially
resolved bands are followed by a re-
gion of approximate transparency
extending from 0.385/1 to 0.426/1 with
its maximum at 0.405/1. Tran.spar-
ency is terminated at 0.426/1 by a
pair of wide, hazy bands of which
the more refrangible is the weaker.
The chief maximum is at 0.505/1.
Absorption ends at 0.545/1. Trans-
parent from 0.545/1 to 0.63/t. More
concentrated solutions show that the
ultra-violet and visible bands soon
run together, whereas the absorption
does not advance much towards the
orange.

60. Congo Corinth G. (A.) Sodium_ salt

of diphenyl - disazo - naphthionic-a-
naphthol-sulphonic acid.

Fig. 23, pi. 6; No. 242, S. & J.

Greenish-black powder. In solution
brownish red, red.

5.38 g. per liter (heated).

Angle 27.3'. Depth o to 0.25 nun.

Absorption in blue-green, green, and
yellow. Very general absorption at
the red border. .A.bsorption band
from 0.46/1 to 0.555/t with its maxi-
mum near 0.5 15/1. The end of the
negative slants considerably, show-
ing that general absorption con-
tinues into the orange. Transparent
to red. Same empirical formula as
No. 61, but different constitution.

61. Congo Rubine. (A.) Sodium salt of

diphenyl-disazo-naphthionic acid - ^ -
naphthol-sulphonic acid.

Similar to fig. 19, pi. 5; No. 243,
S. & J.

Greenish, crystalline powder. In solu-
tion bluish red. dull red.

Saturated (warmed).

Angle 39.0'. Depth 0.26 to 0.62 mm.

COLORING MATTERS.

6i. Congo Rubine — Continued.

Absorption in bhie-green. Absorption,
especially in the visible spectrum,
similar to that of solution No. io6.
A layer about 2 mm. deep absorbs
all the visible si)cctrum except the
orange and red. Complete absorp-
tion at 0.20^ decreases to a minimum
near 0.275(11, then increases to a maxi-
mum at about 0.31/1, and finally van-
ishes in transparency at 0.345(11. Ab-
sorption band from 0.485/x to 0.55ft
with its maximum at 0.52/1. Trans-
parent from 0.55/t to 0.63/1. Same
empirical formula as No. 60, but dif-
ferent constitution.

62. Anthracene Red. (I.) S o d i u m salt

of nitrodiphenyl - disazo - salicylic-a-
naphthol-sulphonic acid.

Similar to fig. 56, pi. 14; No. 262,
S. &J.

Brownish-red powder. In solution deep
red, pink.

7.5 g. per liter.

Angle 27.3'. Depth o to 0.25 mm.

Hazy-edged band in the blue-green
and green. Similar absorption to
that of solution No. 51. Absorption
decreases from 0.20/1 to semi-trans-
parency at 0.29/1. About 0.31/1 a well-
rounded, hazy-edged band starts,
passes through its maximum near
0.36/t, and ceases at 0.42/*. Partial
transparency from 0.42/1 to 0.465/1.
A symmetrical absorption band pre-
vents transmission from 0.465/1 to
0.55/1. Its maximum is near 0.51/1.
Transparent from 0.55/1 to 0.63/1.
Less concentrated solutions show
that the ultra-violet absorption is
comparatively weak.

63. Congo Orange R. (A.) Sodium salt of

ditolyl - disazo - phenetol-j8-naphthyl-
amine-disulphonic acid.

Similar to fig. 11, pi. 3 : No. 275, S. & J.

Yellowish-red powder. In solution
brown, yellowish brown.

5 g. per liter (warmed and filtered).

Angle 39.0'. Depth o to 0.36 mm.

Indefinite, -general absorption in the
blue and blue-green. The liquid is
not clear, but behaves somewhat like
an emulsion. Similar absorption to
that of solution No. 47. Absorption
decreases from 0.20/1 to about 0.29/1
and then remains about constant as
far as 0.365/t. From this point it de-

63. Congo Orange R — Continued.

creases to very weak, general ab-
sorption at 0.43/1. A slight increase
in absorption has its maximum at
0.515/1. It is partly, but not entirely,
due to the weak spot of the Seed
emulsion. Transparent from 0.54/1
to 0.63/1. Deeper layers of greater
concentration show the minimum of
absorption to be the region around

0.455^-

64. Benzopurpurine 6 B. (A.) Sodium

salt of ditolyl - disazo - bi-a-naphthyl-
amine-sulphonic acid.

Similar to fig. 26, pi. 7 ; No. 278, S. & J.

Red powder. In solution red, brownish
red.

7.78 g. per liter (filtered).

Angle 29.3'. Depth o to 0.27 mm.

Hazy-edged band in blue and green.
Similar absorption to that of solu-
tion No. 69. Strong absorption from
0.415/1 to 0.55/1. The chief maximum
of absorption is at 0.51/1. Probably
two hazy, unresolved bands, with
more refrangible, weaker component.
Transparent from 0.55/1 to 0.63/1.
Weaker solutions show more rapid
increase of transparency on the ultra-
violet side of the visible band than
on the red side.

65. Benzopurpurine B. (A.) Sodium salt

of ditoIyl-disazo-bi-/?-naphthylamine-
/?-sulphonic acid.

Similar to fig. 26, pi. 7 ; No. 279, S. & J.

Brown powder. In solution reddish
brown, brown.

8.75 g. per liter.

Angle 25.4'. Depth o to 0.23 mm.

Same visible and photographic absorp-
tion as No. 69. Identical visible ab-
sorption to that of solution No. 64.
Solutions Nos. 65 and 69 seem to
have only one region of absorption
in the ultra-violet, whereas solution
No. 64 has a slight minimum of ab-
sorption near 0.275/1. Nos. 64 and
65 have the same empirical formulae,
but different chemical constitution.

66. Diamine Red B. (A.) Deltapurpurine

5 B. (M.) Sodium salt of ditolyl-

disazo-bi-)3-naphthylamine - sulphonic

acid.
Similar to fig. 26, pi. 7 ; No. 280, S. & J.
Reddish-brown powder. In solution

yellowish red, pink.

32

ATLAS OF ABSORPTION SPECTRA.

66. Diamine Red E — Continued.

6.36 g-. per liter (warmed and filtered).

Angle 25.4'. Depth o to 0.23 mm.

Same visible absorption as No. 64.
Similar absorption to that of solution
No. 69. Nos. 64 and 66 have the
same empirical formulse, but differ-
ent chemical constitutions.

67. Brilliant Congo R. (A). Sodium salt

of ditolyl-disazo - p - naphthylamine-
monosulphonic - j8-naphthylamine-di-
sulphonic acid.

Similar to fig. 26, pi. 7 ; No. 281, S. & J.

Brown powder. In solution, yellowish
red, yellowish red.

8 g. per liter.

Angle 31.2'. Depth o to 0.29 mm.

Hazy-edged band in blue and green.
Similar absorption to that of solution
No. 69. A pair of unresolved bands
extends from 0.42/* to 0.56^, with
their chief maximum at 0.515/*. The
less refrangible band is the more in-
tense. Transparent from 0.555/i to
0.63/1.

68. Diamine Red 3 B. (A.) Sodium salt

of ditolyl-disazo-bi-j8-naphthylamine-
8-sulphonic acid.

Fig. 61, pi. 16; No. 282, S. & J.

Reddish-brown powder. In solution
reddish brown, brown.

7 g. per liter (heated and filtered).

Angle 50.7'. Depth 0.64 mm. to i.io
mm.

Hazy-edged absorption in the blue-
green and green A pair of unre-
solved bands absorbs from about
o.435/t to 0.545/u,. Their maximum
is near 0.515/1. The more refrangible
band is weaker and more indefinite
than its companion. Transparent
from 0.545/1 to 0.63U.

69. Brilliant Purpnrine R. (A.) Sodium

salt of ditolyl-disazo-naphthionic-;8-
naphthylamine-disulphonic acid.

Fig. 26, pi. 7; No. 283, S. & J.

Red powder. In .solution red, pink.

8.75 g. per liter.

Angle 25.4'. Depth o to 0.23 mm.

Same visible and photographic absorp-
tion as No. 67. Nos. 6y and 69 have
the same empirical formulae, but dif-
ferent chemical constitutions. Ab-
sorption gradually decreases from
o.20/t to partial transparency at
0.388/i. This minimum of absorption
extends to 0.411/1. A pair of unre-

69. Brilliant Purpurine R — Continued.

solved bands absorbs all radiations
between 0.41 i/t and 0.563/1. The less
refrangible band is the more intense
and has its ma.ximum at 0.515/1.
Transparent from 0.563/* to 0.63/1.

70. Rosazurine B. (B.) Sodium salt of

ditolyl - disazo - bi - ethyl-;8-naphthyl-
amine-sulphonic acid.

Similar to fig. 26, pi. 7 ; No. 285, S. & J.

Brown powder. In solution red, pink.

7 g. per liter (heated).

Angle 27.3'. Depth o to 0.25 mm.

Weak absorption in the green, with
very hazy, blue boundary. Similar
absorption to that of solution No. 69.
The precise size and shape of the
visible band matches very closely the
corresponding band of solution No.
45, fig. 25. Ab,sorption from 0.47/*.
to 0.55/1, with the maximum near
0.515/t. Transparent from 0.55/1 to
0.63JU.

71. Congo Corinth. Sodium salt of ditolyl-

disazo - naphthionic-a-naphthol-/'-sul-
phonic acid.

Similar to fig. 22, pi. 6; No. 286, S. & J.

Grayish-black powder. In solution red,
pink.

9.09 g. per liter (very gritty; filtered
often).

Angle 21.5'. Depth o to 0.20 mm.

General absorption in green, yellow,
and orange. Very weak and hazy
towards the red. Similar absorption
to that of solution No. 74. Weak,
general absorption in ultra-violet,
permitting all strong lines to pass
through the solution. It fades away
about 0.35/1. Several plates and films
show that absorption begins again
about 0.49/t and becomes relatively
small at 0.56/1. Weak, general ab-
sorption, however, continues to 0.63/1.
The maximum of ab.sorption is inde-
terminate. Saturated solutions gave
the same general results.

72. Azo Blue. (By.) Sodium salt of ditolyl-

disazo-bi-a-naphthol-/>-sulphonic acid.
Somewhat like fig. 22, pi. 6; No. 287,

S. & J.
Bluish-black powder. In solution deep

blue, reddish blue.
4.29 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.
Hazy-edged absorption in green-yellow,

yellow, and orange. The red border

COLORING MATTERS.

33

72. Azo Blue — Continued.

is very indefinite and the maximum
appears to be in the yellow. Ab-
sorption is like that of solution No.
74, except in so far as it is stronger
than No. 74 in the orange. Compara-
tively weak absorption in the ultra-
violet from o.20jii to 0.355/t. There
are slight indications of two ultra-
violet bands with the intervening re-
gion near 0.29/i. Transparent from
0.36/4 to 0.49/x. Absorption begins at
o.49/t, increases to 0.53/x, then fades
to partial transparency near 0.59/1.
Weak absorption from 0.59/1 to 0.63/t.

73. Diamine Black BO. (C.) Sodium salt

of ethoxy-diphenyl-disazo-bi-amido-
naphthol-sulphonic acid.

Suggested by fig. 22, pi. 6; No. 304,
S. & J.

Black powder. In solution blue, blue.

7.5 g. per liter.

Angle 31.2'. Depth o to 0.29 mm.

Strong absorption in the yellow and
orange with diffuse borders. Red is
transmitted. The absorption is some-
what like that of solution No. 74
except in so far as it is stronger than
No. 74 in the orange. Absorption
decreases from o.20/i to about 0.37/t.
Transparent from 0.37/t to 0.51/1.
Absorption extends from 0.5 i/t into
the clear red. The maximum of ab-
sorption is indefinite.

74. Benzopurpurine 10 B. (A.) Sodium

salt of dimethoxy-di-phenyl-disazo-
bi-napluHonic acid.

Fig. 22, pi. 6 ; No. 307, S. & J.

Brownish-red powder. In solution red,
pink.

5.83 g. per liter.

Angle 23.4'. Depth 0.05 to 0.26 mm.

Chief absorption in the green. The
visible band extends from about
0.48/1 to o.55/t with its maximum at
0.515/1. The slanting end of the nega-
tive denotes general absorption in
the orange.

75. Benzoazurine. Sodium salt of dimeth-

oxy-diphenyl disazo-bi-a-naphthol-/>-
sulphonic acid.

Somewhat like fig. 22, pi. 6; No. 311,
S. & J.

Bluish-black powder. In solution red-
dish blue, blue.

7.5 g. per hter.

75. Benzoazurine — Continued.

Angle 25.5'. Depth o to 0.21 mm.

No very definite, visible band, but a
general weakening of the green, yel-
low, orange, and red. The ultra-
violet absorption is weak and ends
near 0.355/*. The region of general
absorption begins about 0.5 i/t and
continues beyond 0.63/1. There is a
weak maximum near 0.53/4. The
end of the negative slants to an un-
usual degree. The contour of the
weak band is V-shaped like the
visible band for solution No. 74.

76. Diamine Green B. (C.) Sodium salt

of diphenyl - disazo-phenol-disulpho-
amidonaphthol-azo-nitrobenzene.

No. 372, S. & J. *

Dull-gray, crystalline powder. In solu-
tion bluish green, bluish green.

3 g. per liter.

Angle 17.0'. Depth o to 0.14 mm.

Gradual absorption in the orange and
red. Very weak absorption in the
ultra-violet from 0.20/4 to about
0.38/4. No visible or photographic
absorption between 0.38/4 and 0.6/1.
General absorption begins about 0.6/1.
yy. Congo Brown G. (A.) Sodium salt of
sulpho - benzene-azo-resorcinol - azo-
diphenyl-azo-salicylic acid.

Figs. 35 and 36, pi. 9 ; No. 379, S. & J.

Brown powder. In solution light brown,
yellow.

4.67 g. per liter.

Angle 27.3'. Depth o to 0.25 mm.

Absorption in violet, blue, and green.
Very hazy at green side. Absorp-
tion decreases from 0.20/4 to a some-
what transparent region around
0.295/1. Maximum absorption at
0.365/4. Absorption ceases at 0.53/t.
A weaker solution (fig. 36) showed
transparency from 0.29/4 to 0.315/1.
Absorption from 0.315/t to 0.428/4.
Maximum absorption at 0.365/4, as
before. Transparent to yellow,
orange, and red.
78. Congo Brown R. (A.) Sodium salt of
sulpho-naphthalene-azo-resorcin-azo-
diphenyl-azo-salicylic acid.

Fig. 35,pl. 9;No. 380, S. &J.

Dark, brownish-red powder. In solu-
tion reddish brown, yellow.

Saturated.

Angle 29.3'. Depth o to 0.27 mm.

♦Spectrogram too indefinite for reproduction.

34

ATLAS OF ABSORPTION SPECTRA.

78. Congo Brown R — Continued.

Same visible and photographic absorp-
tion as No. 77. The change in tlie
constitution is from benzene to naph-
thalene.

79. Fast Green O. (M.) Dinitroso-resor-

cinol. (Dioximidoquinone.)

Similar to fig. 11, pi. 3 ; No. 394, S. & J.

Grayish-brown powder. In solution
deep cofifee brown, coffee brown.

Saturated (heated).

Angle 1° 6'. Depth 0.05 to 0.66 mm.

General absorption in violet and blue.
Similar absorption to that of solu-
tion No. 47. The boundaries of the
hands, however, are more definite for
solution No. 79 than for solution No.
47. From o.20;u, to 0.325^4 the ab-
sorption is complete. Absorption de-
creases with a long, gradual slope,
from 0.325/^ to a minimum of semi-
transparency at 0.47S/J.. Then a
weak band with maximum at 0.52/i
presents itself and continues to o.S4lf-
Only very weak absorption is
present from 0.54/i to 0.63/^. With
the same solution and the cell
set for 35.1' and 0.32 mm. the ab-
sorption was almost complete from
o.20fi to o.30;u. and then sloped gradu-
ally to transparency at 0.405/4. The
band at 0.52/A could not be dis-
cerned.

80. Naphthol Green B. (C.) Ferrous so-

dium salt of nitroso-/?-naphthol-^-
monosulphonic acid.

Fig 10, pi. 3 ; No. 398, S. & J.

Dark-green powder. In solution green,
light green.

8.75 g. per liter (boiled).

Angle 31.2'. Depth o to 0.29 mm.

Absorption in violet and in dark red.
Absorption very strong from o.zOfj.
to 0.3 i/n. Then the absorption de-
creases very gradually, with a long
slant, to o.455ft. From 0.455/4 to the
orange the transparency is complete.
Absorption begins again in the red.

81. Curcumine S. (A.) Sodium salt of

the so-called azoxy - stilbene - disul-

phonic acid.
Fig. 37, pi. 10; No. 399, S. & J.
Brown powder. In solution yellow,

faint yellow.
Saturated.
Angle 1° 10'. Depth o.ii to 0.75 mm.

81. Curcumine S — Continued.

Faint absorption in violet. Absorption
decreases from 0.20/i to 0.29/4. Trans-
parent from 0.29/A to 0.34/1. Weak
band from 0.34/1 to 0.43/4 with max-
imum at 0.39/1. Transparent from
0.43/1 to 0.63/4.

82. Auramine O. (B.) Hydrochloride of

amido-tetramethyl-diamido-diphenyl-
methane.

Fig. 43, pi. 11; No. 425. S. & J.

Sulphur-yellow powder. In solution
yellow, faint yellow.

Equal volumes of a saturated solution
and of water (filtered).

Angle 42.5'. Depth o to 0.36 mm.

Strong absorption in violet and indigo.
Relatively transparent at 0.22/1. The
continuous background of the spark
indicates one band or, at most, two
bands from 0.23/1 to 0.275/1. Un-
usually transparent from 0.275/4 to
0.345/4. A pair of partially-resolved
intense bands absorb from 0.345/1 to
o.47/t. Their maxima lie at 0.365/1
and 0.425/1. The intervening, par-
tially-transparent spot is near 0.385/1.
The less refrangible band is the more
intense and is very round. Trans-
parent from 0.470/4 to 0.63/1.

83. Malachite Green. (M.) Oxalate of

tetramethyl - di-/»-amido - triphenyl-
carbinol.

Similar to fig. 46, pi. 12; No. 427,
S. & J.

Green, metallic, glistening plates. In so-
lution greenish blue, greenish blue.

3.75 g. per liter.

Angle 25.5'. Depth o to 0.21 mm.

Strong, double band in the orange and
clear red. Deep red is transmitted.
Similar absorption to that of solution
No. 86 from 0.20/4 to the yellow. All
strong lines in the extreme ultra-
violet are transmitted freely. Ab-
sorption band lies between 0.29/4 and
0.33/1. A faint band has its maximum
near 0.425/4. Strong absorption com-
mences at 0.55/4.

84. Emerald Green. (B.) Sulphate or

zinc - double - chloride of tetraethyl-
diamido-triphenyl-carbinol.

Similar to fig. 46, pi. 12; No. 428,
S. & J.

Golden, glistening crystals. In solu-
tion green, green.

4.62 g. per liter.

COLORING MATTERS.

35

84. Emerald Green — Continued.

Angle 31.2'. Depth o to 0.29 mm.

Compound band in the orange and red
with the maximum in the red. The
contour is hazy. Similar absorption
to solution No. 86 from 0.20/x to the
yellow, save that the band near
0.425;^ is hardly discernible on the
negative. Strong absorption begins
at 0.57/x. For ultra-violet details see
No. 83 above.

85. Light Green F S. (B.) Sodium salt of

dimethyldibenzy 1 - diamido - triphenyl-
carbinol-trisulphonic acid.

Similar to fig. 46, pi. 12; No. 434,
S. &J.

Brownish-black powder. In solution
green, green.

10 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Strong band in the yellow, orange, and
red. Except for concentration, the
absorption is the same as that of so-
lution No. 86, hence for further de-
tails refer to No. 86.

86. Acid Green, concentrated. (C.) Sodium

salt of diethyldibenzyl - diamido - tri-
phenyl-carbinol-trisulphonic acid.

Fig. 46, pi. 12; No. 435, S. & J.

Bright-green, dull powder. In solution
deep green, green.

13-33 g- per liter.

Angle 25.4'. Depth o to 0.23 mm.

Strong band in orange and red with
no return to transparency visible.
Absorption in violet and blue. Ab-
sorption -decreases from 0.20/t to
about 0.275/1. Then a strong band
begins, having its maximum near
0.32/* and returning abruptly to
transparency at 0.34/^. Transparent
from 0.34/i to 0.39/i. A round band
extends from 0.39/i to 0.455/1 with
its maximum at 0.425/1. Transpar-
ent from 0.455/1 to 0.55/1. Strong ab-
sorption commences at 0.55/1 and in-
creases to complete opacity at 0.63/1.
Weaker solutions show conclusively
the transparent region around 0.275/1
and also that the band at 0.425/1 van-
ishes most readily.

87. Fuchsine. (M.) Mixture of hydro-

chloride or acetate of pararosa'niline

and rosaniline.
Fig. 48, pi. 12; No. 448, S. & J.
Green, crystalline powder. In solution

deep red, red.

87. Fuchsine — Continued.

Angle 21.3'. Depth o to 0.18 mm.

Intense band in blue-green and green.
All lines near 0.23/1 and from 0.25/1
to 0.26/1 are freely transmitted. The
background indicates a band with
its maximum at 0.285/1 and extend-
ing from 0.27/1 to 0.305/1. Transpar-
ent from 0.305/1 to 0.45/1. Very
strong absorption from 0.45/1 to
°-575l^ with maximum near 0.53/1.
There are probably two unresolved
bands of which the more refrangible
is the weaker. Transparent from
0-575/^ to 0.63/1. A layer about i mm.
deep limited the more refrangible,
transparent region to the interval
from 0.35/1 to 0.39/1.

88. New Magenta. (O.) Hydrochloride of

triamido-tritolyl-carbinol.

Fig. 50, pi. 13 ; No. 449, S. & J.

Beetle-green powder. In solution red,
bluish red.

6 g. per liter.

Angle 31.2'. Depth o to 0.29 mm.

Strong band in the green, steeper on
the yellow side, and suggesting a
sharp band superposed upon a
weaker one. The band extends from
about 0.44/1 to 0.56/1 with its maxi-
mum near 0.52/1. Transparent from
0.56/1 to 0.63/1.

89. Dahlia. _ (B.) Mixture of the hydro-

chlorides or acetates of the mono-
di- or tri-methyl (or ethyl) rosani-
lines and pararosanilines.

Fig. 69, pi. 18; No, 450, S. & J.

Green, lumpy powder. In solution deep
blue, reddish violet.

3.57 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Absorption commences in the blue-
green, has its maximum in the green-
yellow, and decreases gradually into
the red. Transparent to deep red.
Absorption in ultra-violet is weak.
A band which is definite on the more
refrangible edge commences at 0.48/1
and increases to a maximum at
0.52/i. A weak, unresolved com-
panion joins the last one near 0.57/1
and fades away at 0.62/1.

90. Crystal Violet. (B.) Hydrochloride of

hexamethyl-pararosaniline.
Similar to fig. 66, pi. 17; No. 452,
S. & J.

36

ATLAS OF ABSORPTION SPECTRA.

90. Crystal Violet — Continued.

Cantharides glistening crystals. In so-
lution violet, violet.

1.38 g. per liter.

Angle 42.5'. Depth o to 0.36 mm.

The absorption is the same as that ex-
hibited by solution No. 92, hence see
the description given below.

91. Ethyl Violet. (B.) Hydrochloride of

hexaethyl pararosaniline.

Fig. 64, pi. 16; No. 453, S. & J.

Green, crystalline powder. In solution
pure, deep blue, pinkish blue.

2.73 g. per liter.

Angle 27.3'. Depth o to 0.25 mm.

Intense absorption in the green. Very
sharp and abrupt on the blue side
but indefinite on the red border.
Strong lines in the ultra-violet are
transmitted pretty freely. Relative
transparency in the vicinity of 0.265/^.
Absorption ceases about 0.31/* and
from this wave-length to 0.495/1
transparency obtains. At 0.495^11 an
intense band having its maximum at
o.525(Li begins. About 0.585/i the ab-
sorption becomes relatively weak and
diffuse and continues thus to 0.63^4.

92. Methyl Violet 6 B. (A.) Chiefly a mi.x-

ture of the hydrochlorides of benzyl-
pentamethylpararosaniline and hexa-
methylpararosaniline.

Fig. 66, pi. 17; No. 454, S. & J.

Metallic, glistening powder. In solu-
tion blue, reddish blue.

2.5 g. per liter.

Angle 31.2'. Depth o to 0.29 mm.

Transmits only blue and pure red in
concentrated solution. The solution
described below showed two bands,
the more intense in the green-yellow
and the weaker in the orange. All
strong ultra-violet lines are trans-
mitted. The chief band starts at
0.50/4, has its maximum at 0.535/1,
and joins its companion about 0.57/x.
The weaker band has its maximum
at 0.595/4 and fades away at 0.615/1.
Transparent from 0.62/1 to beyond
0.6^/4.

93. Methyl Green 00. (By.) Zinc-double-

chloride of hepta-methyl-pararosani-

line-chloride.
Similar to fig. 47, pi. 12; No. 460,

S. & J.
Green crystals. In solution greenish

blue, greenish blue.

93. Methyl Green OO — Contimied.

6 g. per liter.

Angle 19.5'. Depth o to 0.18 mm.

Band in violet and blue, also strong
absorption in orange and red. The
band in the orange is partly sepa-
rated from the stronger band whose
intensity increases to, and beyond,
0.63/t. With due allowance for dif-
ferences in concentration, it ap-
pears that the absorption is, in
toto, the same as that shown by
solution No. 94. Absorption de-
creases from 0.20/4 to a region of
less intense absorption at 0.28/4.
Then follows a strong band with
maximum at 0.315/1. A band from
0.375/4 to 0.445/1 has its maximum
at 0.415/4. The yellow and orange
band begins at 0.515/4.

94. Methyl Green. Zinc-double-chloride of

ethylhexamethyl - pararosaniline bro-
mide.

Fig 47, pi. 12; No. 461, S. & J.

Moss-green, crystalline powder. In
solution bluish green, bluish green.

20 g. per liter.

Angle 19.5'. Depth o to 0.18 mm.

Band in violet and blue, also strong
absorption in orange and red. Trans-
mits green and yellow-green. Band
from 0.36/1 to 0.45/1 with maximum
at 0.415/4. This band is steeper on
its green side. Very transparent
from 0.45/t to 0.495/4. From 0.495/1
the absorption is intense and no re-
turn to transparency can be seen at
0.63/1. The band at 0.415/1 disap-
pears first on dilution.

95. Fuchsine S. (B.) Mixture of the so-

dium or ammonium salts of the tri-
sulphonic acids of rosaniline and
pararosaniline.

Fig. 53, pi. 14; No. 462, S. & J.

Metallic, green, glistening powder. In
.solution red, red.

3 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Strong absorption in the blue-green
and green. The middle of the first
transparent region is about 0.265/t.
A weak absorption band has its
maximum near 0.295/4. The visible
band commences at 0.475/4, has its
maximum about 0.535/4, and ends at
o. 575/4. Transparent from 0.575/4 to
0.63/4.

COLORING MATTERS.

37

96. Red Violet 5 R S. (B.) Sodium salt of

ethylro5aniline-sulphonic acid.

Fig. 62, pi. 16; No. 463, S. & J.

Ilrownish - violet, metallic, glistening
lumps. In solution brownish red,
brownish red.

.Saturated.

Angle 58.5'. Depth o to 0.54 mm.

General absorption in the green, yel-
low, and orange. The ultra-violet
absorption is complete from 0.20/i.
to 0.36/x. Absorption decreases
gradually from o.36,u to a minimum
of general absorption near 0.47/i. A
weak band has its maximum about
0.525;!. The marked slant of the end
of the negative shows the presence
of appreciable g'eneral absorption in
the yellow and orange. Red is trans-
mitted.

97. Alkali Blue 6 B. (A. A. C.) Sodium

salt of triphenyl-/'-rosaniline - mono-
sulphonic acid.

Fig. 72, pi. 18; No. 476, S. & J.

Blue powder. In solution blue, deli-
cate blue.

12.5 g. per liter (heated).

Angle 23.4'. Depth o to 0.21 mm.

Strong absorption in yellow, orange,
and red. Intense, continuous absorp-
tion from o.20/t to 0.32/x. Abrupt
decrease in absorption from 0.32/i to
transparency at 0.345/11. Transparent
from 0.345/i to 0.51/1. Strong ab-
sorption from 0.51/1 to beyond 0.63/4.
No decrease in absorption as far as
0.63/1. The apparent increase in ab-
sorption near 0.62/1 is due to the
relative diminution of sensitiveness
of the photographic emulsion.

98. Methyl Blue. (O.) Sodium salt of tri-

phenyl - pararosaniline - trisulphonic
acid.

Similar to fig. 71, pi. 18; No. 479,
S. &J.

Dark-blue powder. In solution deep,
bright blue, blue.

6.89 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Strong absorption in the yellow, orange,
and red. The description for solu-
tion No. 99 holds here quantitatively.

99. China Blue. (A.) Sodium salt of the

trisulphonic acid of triphenylrosani-
line and triphenylpararosaniline.
Fig. 71, pi. 18; No. 480, S. & J.

99. China Blue — Continued.

Coppery flakes. In solution blue, blue.

3-57 S- V^^' 'iter (filtered).

Angle 23.4'. Depth o to 0.21 mm.

A hazy-edged band begins in the green
and continues into the red. The
strong lines around 0.255/1 are trans-
mitted by the deepest layer of liquid.
Absorption is more or less uniform
from 0.20/1 to 0.32/1 and then shades
off to transparency at 0.345/1. Trans-
parent from 0.345/1 to 0.505/1. Then
a band starts and continues with un-
diminished intensity to 0.63/1.

100. Coralline Red. Dioxy-amido-triphenyl-

carbidrid.

Fig. 49, pi. 13 ; No. 484, S. & J.

Reddish-brown lumps. In solution red,
salmon pink.

11.25 §■• per liter (heated).

Angle 19.5'. Depth o to 0.18 mm.

Sharp band in blue and green. Very
definite at yellow side with maxi-
mum in green-yellow. Rather strong
absorption from 0.20/1 to 0.27/1, then
a decrease to transparency at 0.315/1.
Strong absorption from 0.445/1 to
0-557y" with maximum at 0.527/1.
Probably two unresolved bands with
the weaker component at the more
refrangible side. Transparent from
0.557/1 to 0.63/1.
loi. Night Blue. (B.) Hydrochloride of
/'-tolyltetraethyl-triamido - diphenyl-
a-naphthyl-carbinol.

Similar to fig. 70, pi. 18; No. 480.
S. & J.

\ iolet, bronzy powder. In solution
bright blue, blue.

2-31 g- per liter.

Angle 23.4'. Depth o to 0.21 mm.

Absorption in the yellow, orange, and
red. The limit at the green side is
steep and the curve is flat in the
longer wave-lengths. The visible re-
gion of absorption begins about
°-5~5f^- For the ultra-violet absorp-
tion see fig. 70.
102. Victoria Blue 4 R. (B.) Hydro-
chloride of phenylpenta-methyl-tri-
amido-diphenyl - a - naphthyl - car-
binol.

Fig. 70, pi. 18; No. 490, S. & J.

Bronzy, glistening powder. In solution
deep blue, reddish blue.

2.78 g. per liter (heated).

Angle 27.3'. Depth o to 0.25 mm.

38

ATLAS OF ABSORPTION SPECTRA.

1 02. Victoria Blue 4 R— Continued.
Hazy-edged absorption in yellow and

orange. The red is only partially
absorbed. Comparatively weak ab-
sorption decreases steadily from
o.20/i to about 0.335/1. A band com-
mences at 0.495/j, and continues to a
maximum at 0.53/x. From this point
the band shades off gently towards
the red. (The apparent increase of
absorption at 0.62^ is probably due
to the increasing lack of sensitive-
ness of the plate.)

103. Rhodamine B. (B.) Hydrochloride of

diethyl-m-amido-phenol-phthaleine.

Fig. 65, pi. 17; No. 504, S. & J.

Reddish-violet powder. In solution
bluish red, violet.

7.5 g. per liter.

Angle 42.5'. Depth o to 0.36 mm.

Two distinct bands, the one in the yel-
low-orange and the other in the
green-yellow. Eye observations,
changes in concentration, and differ-
ent makes of films show that the
more refrangible band is the more
intense. Fluorescent solution. Ab-
sorption decreases gradually from
o.20/i to an indefinite limit near 0.32U.
Strong absorption from 0.494/j. to
about 0.59/i. The maxima are at
0.524/i and o.557;u. with the inter-
vening minimum of absorption at
0.54/j.. Transparent beyond the
orange band into the red.

104. Fast Acid Violet B. (M.) Sodium

salt of diphenyl - m - amido-phenol-
phthalein sulphonic acid.

Fig. 63, pi. 16; No. 506, S. & J.

Maroon powder. In solution bluish
red, pink.

3-33 g- per liter.

Angle 27.3'. Depth o to 0.25 mm.

Absorption band in the green-yellow.
This band is comparatively definite
on the green side and has a shadowy
companion on the red side. General
absorption continues well into the
orange-red. All strong lines in the
ultra-violet are transmitted. The
ultra-violet absorption ends about
o.33fi. The visible band begins at
0.505/4 and has its maximum near
0-53/*- The less refrangible limit is
indeterminate. The essential differ-
ence between the spectrograms for
solutions Nos. 104 and 106 is tliat

104. Fast Acid Violet B — Continued.

for the former the visible band is
asymmetric, whereas for the latter
it is symmetric.

105. Fast Acid Violet A 2 R. (M.) Sodium

salt of di-o-tolyl - m - amido-phenol-
phthalein-sulphonic acid.

Similar to fig. 19, pi. 5 ; No. 507, S. & J.

Violet-red powder. In solution red,
pink.

4.67 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Very narrow, definite band in the
green. All strong ultra-violet lines
are transmitted. The ultra-violet ab-
sorption ends about 0.335/1. The
visible band begins at 0.495/t, has its
maximum at 0.525/i, and ends near
0.57/1. The slanting end of the spec-
trogram indicates general absorption
in the deep yellow. The green band
for this solution is of the same type
as the corresponding one for No.
104, although it is much less asym-
metric, and therefore it resembles
more closely No. 106. The spectrum
of solution No. 105 is best described
as a transition form between Nos.
104 and 106. Solutions Nos. 104
and 105 have the same empirical
formulae.

106. Acid Rosamine A. (A.) Sodium salt

of di - mesidyl - m - amido - phenol -
phthalein-sulphonic acid.

Fig. 19, pi. 5 ; No. 508, S. & J.

Light-red powder. In solution red,
pink.

10 g. per liter.

Angle 29.3'. Depth o to 0.27 mm.

Single V-shaped band in the green.
Weak absorption beginning with ex-
tinction at 0.20/1 and fading gradu-
ally to transparency at 0.32/1. Ab-
sorption band covers the interval
from 0.505/1 to 0.565/1 with its max-
imum at 0.535/1. Transparent from
0.565/* to 0.63/t.

107. Uranine. (B.) Sodium or potassium

salt of fluoresceine.

Figs. 15 and 16, pi. 4; No. 510, S. & J.

Yellowish-brown powder. In solution
reddish yellow, yellow.

Intense, narrow band in the blue-green
with a weaker companion on its more
refrangible side. Very strong, yel-
lowish-green fluorescence.

COLORING MATTERS.

39

107. Uranine — Continued.

Fig. 16 resulted from a solution of 2 g.
per liter.

Angle 23.4'. Depth o to 0.21 mm. Only
the stronger band shows. Here it
extends from 0.480/n to 0.504/* with
its maximum at 0.493/x.

Fig. 15 corresponds to 2.67 g. per liter.
The angle 31.2' gives a maximum
depth of 0.49 mm. Complete trans-
parency from 0.330/* to 0.443/*. The
spectrogram shows that the visible
region of absorption has roughly
parallel sides which are very definite.
The visible maximum is at 0.493/i
as before. At the outer edge of the
fifth strip the absorption covers the
interval from 0.443/* to 0.515/*.

A solution of 5 g. per liter, of angle
42.5', and of depth o to 0.36 mm.,
absorbed from 0.432/* to 0.518/* with
the maximum at 0.493/1.

A solution of 20 g. per liter with an
angle of 42.5' caused the ultra-violet
and visible absorption bands to
coalesce, on the third photographic
strip, in a semi-transparent region
extending roughly from 0.355/1 to
0.395/*. Intense absorption from
0.395/1 to 0.533/*. The short wave-
length boundary is indefinite, but the
opposite limit is very sharply de-
fined and steep. Maximum absorp-
tion at 0.493/t.

Tests were made to ascertain whether
or not the conditions were favor-
able to c'Dntamination of the absorp-
tion spectra by the fluorescent light.
The most dilute solution was illu-
minated with intense ultra-violet
light and an exposure of five min-
utes was given to the photographic
film. Full development of the film
brought out no trace of previously
incident light. Therefore, since the
Nernst glower alone was used in
making the records of the visible
bands and because, in all cases ex-
cept one, more concentrated solutions
were used, it follows that the spec-
trograms are correct representations
of the absorption, at least so far
as the fluorescent light is concerned.
108. Eosine, yellowish. (A.) Alkali salts
of tetrabromo-fluoresceine.
Fig. 58, pi. 15; No. 512, S. & J.

108. Eosine, yellowish — Continued.

Deep red powder. In solution yellow-
ish red, pink.

20 g. per Hter.

Angle 21.3'. Depth o to 0.18 mm.

Very strong absorption in blue and
green. Faint green fluorescence in-
creasing with dilution. Intense ab-
sorption from 0.20/1 to 0.33/*. The
absorption then decreases, first gradu-
ally and then steeply, to partial trans-
parency at 0.37/1. This transparent
region continues as far as 0.434/*.
Intense absorption from 0.434/* to
0.56/*. From 0.515/1 to 0.525/1 the
solution is almost opaque. Two un-
resolved bands seem to be present.
The more refrangible boundary of
the visible absorption is less definite
than the opposite side. The latter
limit is steep and sharp. Transpar-
ent from 0.56/1 to 0.63/1.

109. Eosine a I'alcool. (B.) Potassium

salt of tetrabromo-fluoresceine-ethyl-
ether.

Fig"- 17. Pl- 5; No. 514, S. & J.

Brown powder mixed with small,
green crystals. In solution red, pink.

4.29 g. per liter (heated).

Angle 46.8'. Depth o to 0.43 mm.

Sharp, narrow band in green, abrupt
on yellow side and diffuse on the
blue side due to a faint companion
band. Slight greenish-yellow fluo-
rescence. Very weak absorption in
extreme ultra-violet. Absorption be-
gins at 0.495/* ^nd ends at 0.540/*.
The chief maximum is at 0.525/1.
Transparent from 0.540/* to 0.63/t.

1 10. Methyl Eosine. (A.) Potassium salt

of dibromodinitro-fluoresceine.

Similar to fig. 58, pi. 15; No. 515,
S. & J.

Brown, crystalline powder. In solution
red, orange.

10 g. per liter.

Angle 15.6'. Depth o to 0.14 mm.

Intense band in blue and green. Ap-
parently two unresolved bands. Sim-
ilar absorption to that of solution
No. 108. Absorption is rather com-
plete from o.20/t to 0.30/1 and then
decreases to about 0.36/*. Strong
absorption from 0.46/* to 0.56/1. The
principal maximum is at 0.52/1. Very
transparent from 0.56/* to 0.63/1.

40

ATLAS OF ABSORPTION SPECTRA.

111. Eosine, bluish. (B.) Sodium salt of

tetraiodo-fluoresceine.

Similar to fig. 58, pi. 15; No. 517,
S. & J.

Lavender powder. In solution red,
pink.

15 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Intense absorption in the blue-green.
Similar absorption to that of solu-
tion No. 108. The yellowish-green
fluorescence only appears in dilute
solutions. Absorption decreases
gradually from 0.20/i to 0.36/^. In-
tense absorption from 0.45 5/t to
o.555/i. Maximum of absorption at
o.52;u. There seem to be two unre-
solved bands of which the more re-
frangible is a little less intense than
its companion. This region of ab-
sorption is sharper and steeper at
its yellow border. Transparent from
0.555/* to 0.63/1.

112. Erythrosine. (M.) Sodium salt of

tetraiodo-fluoresceine.

Fig. 59, pi. 15; No. 517, S. & J.

Dark-red powder. In solution red,
pink.

15 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Intense absorption in the blue and
green. A strong hand in the middle
with a slightly weaker, unresolved
companion on each side. The yel-
lowish-green fluorescence only ap-
pears in dilute solutions. The re-
gion of visible absorption is from
0.455^ to 0.562/i. The chief maxi-
mum is about 0.518/i. The yellow
edge of this group of bands is very
sharply defined. Transparent from
0.562/* to 0.63/*.

113. Cyanosine. (M.) Alkaline salt of

tetra - bromodichloro - fluoresceine-
methyl-ether.

Fig. 18, pi. 5; No. 519. S. & J.

Brownish-red powder. In solution red,
bluish pink.

Saturated (boiled).

Angle 25.4'. Depth o to 0.23 mm.

Band in blue-green and green. Faint,
yellowish fluorescence. Strong ab-
sorption from 0.493/1 to o.553/i"with
its maximum at 0.525/*. Transpar-
ent from 0.553/1 to 0.63/1.

114. Rose Bengal. (B.) Alkaline salt of

tetraiododichloro-fluoresceine.

Similar to fig. 59, pi. 15; No. 520,
S. & J.

Brown powder. In solution red, orange.

15 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Double, unresolved pair of bands in
green. In amyl alcohol the bands
were nearly resolved. Strong ab-
sorption from o.20/t to about 0.33/t,
except a slight weakening at 0.295/1.
Transparent from 0.33/1 to 0.48/1.
Strong absorption from 0.48/1 to
0.575/t. Transparent from 0.575/t to
0.63/t.

115. Phloxine. (B.) Sodium salt of tetra-

bromotetra-chloro-fluoresceine.

Fig. 60, pi. 15; No. 521, S. & J.

Brick-red powder. In solution cherry
red, pink.

12.5 g. per liter.

Angle 42.5'. Depth o to 0.36 mm.

Intense absorption in the green. Dark-
green fluorescence. Visible band lies
between 0.458/1 and 0.57/1. The max-
imum is near 0.525/1. For dilute so-
lutions the absorption is very much
like that shown by fig. 18, except
that the contour of the band in the
green is sharper than for solution
No. 113.

116. Galleine. (By.) Pyrogallol-phthalein.
Similar to fig. 1 1, pi. 3 ; No. 525, S. & J.
Violet brown powder. In .solution very

dark brown, brown.

Saturated (heated).

Angle 58.5'. Depth o to 0.54 mm.

Ilazy-edged absorption in the blue-
green and green. Absorption is com-
paratively strong at 0.20/1 and de-
creases very gradually to semi-trans-
parency about 0.435/t. Only partial
transparency exists between 0.435/1
and 0.485/4. A V-shaped band ab-
sorbs from 0.485/4 to o.553/t. The
maximum is about 0.52/t. The end
of the negative slants a good deal,
showing general absorption in the
yellow-orange. The spectrogram is
like that which would be obtained
with a more concentrated solution of
No. 47 if it were possible to produce
such a condition.

COLORING MATTERS.

41

117. Phospliiiie. (M.) Nitrate of chrysaiii-

line ( iiiis}!!!. diamido - phenyl - acri-
dine) and homologues.

Fig. 32, pi. 8;No. 532, S. & J.

Orange-yellow powder. In solution
brown, yellow.

11.25 t?- per liter (heated and filtered).

.\ngle 27.3'. Depth o to 0.25 mm.

Absorption in violet, blue, and green
with hazy limits. Strong absorption
from o.20ytt to 0.295/n, then weaken-
ing to semi-transparency at 0.325/^.
Next a band with maximum at
0.36/4. Return to partial transpar-
ency at 0.41/X. Then follow two un-
resolved bands with maxima about
0.458/4 and 0.50/1. Complete trans-
parency from 0.52/4 to 0.62/1. A solu-
tion so concentrated as to absorb all
the ultra-violet and visible spectrum
from 0.20/4 to 0.538/1 was transpar-
ent to 0.63/1.

1 18. Alizarine Brown. (M.) Trio.xyanthra-

quinone.

Similar to fig. 11, pi. 3 : No. 538, S. & J.

Dark-brown powder. In solution dull
brown, brown.

Saturated.

Angle 35.1'. Depth o to 0.32 mm.

General, indefinite absorption except
in the red. Absorption intense and
uniform from 0.20/1 to 0.33/1. From
0.33/4 the absorption decreases very
gradually and nearly linearly to
about 0.47/t. A very weak band with
its maximum at 0.52/4 exists over
and above the intensity minimum of
the sensitized film. The end of the
negative slopes appreciably, denoting
continued general absorption in the
orange. No visible weakening of the
red. A maximum of transparency is
around 0.48/t. The spectrograms for
solutions Nos. 116 and 118 are very
similar.

119. Alizarine Red S. (B.) Sodium salt of

alizarine-monosulphonic acid.

Fig. 14, pi. 4; No. 546, S. & J.

Orange-yellow powder. In solution
reddish yellow, yellow.

12 g. per liter (heated and filtered).

Angle 30.0'. Depth o to 0.45 mm.

Absorption in violet and blue. Opaque
from 0.20/4 to 0.275/1. Absorption
decreases gradually from 0.275/1 to
partial transparency at 0.377/1, and

119. Alizarine Red S — Continued.

then increases to a maximum at
0.42/1. Absorption ends at 0.485/1.
No visible absorption from 0.49/4 to
0.63/4.

120. Alizarine Blue S. (B.) Sodium bisul-

phite compound of dioxy - anthra-
quinone-/8-quinoline.

Fig. 28, pi. 7 ; No. 563, S. & J.

Chocolate-brown powder. In solution
yellowish brown, brown.

7-37 g- per liter.

Angle 58.5'. Depth o to 0.54 mm.

Ab.sorption in violet, blue, and green.
The absorption extends into the
ultra-violet. Absorption from 0.20/1
to 0.33/4 is almost complete .save a
slight weakening around 0.285/4. In-
tense maximum at 0.315/t. Absorp-
tion decreases abruptly from be-
yond 0.33/1 to transparency at 0.36/4.
The transparent region is from
0.36/4 to about 0.385/1. A pair of
wide bands absorbs from 0.385/4 to
0.543/4. Their maxima are at 0.44/t
and 0.517/4. The intervening mini-
mum of absorption is at 0.48/4.
Transparent from 0.543/1 to 0.63/4.
The ultra-violet bands remain very
intense even when dilution causes
the visible bands to disappear.

121. Neutral Red. (D. H.) Hydrochloride

of dimethyldiamido-toluphenazine.

Similar to fig 54, pi. 14; No. 580,
S. & J.

Dark-green powder. In solution red,
pink.

3 g. per liter.

Angle 39.0'. Depth o to 0.36 mm.

Band in blue and blue-green, not sharp
at edges. Very similar absorption
to that of solution No. 122. Slight
tran,sparency at 0.23/t. A band lies
between this point and 0.31/4 where
transparency begins to be complete.
An absorption band extends from
0.468/1 to 0.545/4 with its maximum at
0.507/4. Transparent from 0.545/4 to
0.63/4.

122. Phenosafranine. Diamidophenyl-phena-

zonium chloride.
Fig. 54. pi. 14 ; No. 583, S. & J.
Green, glistening crystals. In solution

clear red, pink.
2.5 g. per liter.
Angle 39.0'. Depth o to 0.36 mm.

42

ATLAS OF ABSORPTION SPECTRA.

122. Phenosafranine — Continued.

Band in blue and blue-green, not sharp
at edges. The ultra-violet band ends
about 0.3 i/i,. The visible band ab-
sorbs from o.45ft to 0.545/x with
maximum at 0.50/^. Transparent
from 0.545^11 to 0.63/x.

123. Safranine. (B.) Mixture of diamido-

phenyl- and tolyl-tolazonium chlo-
rides.

Similar to fig. 54, pi. 14; No. 584,
S. & J.

Reddish-brown powder. In solution
red, red.

5 g. per liter.

Angle 27.3'. Depth o to 0.25 mm.

Definite absorption in blue-green and
green. Similar absorption to that
of solution No. 122. Strong ab-
sorption from o.20fi to 0.28/x. Rapid
decrease in absorption from o.28|t
to 0.32^. Absorption begins again
at 0.44/i, increases to a maximum
near o.495;u,, and then decreases to
transparency at 0.555/1. Transparent
from o.555;tt to 0.63/*.

124. Heliotrope 2 B. (A.) Dimethyldiam-

ido-xylyl - xylophen-azonium chlo-
ride.

Fig. 68, pi. 17; No. 590, S. & J.

Grayish-green powder. In solution
reddish violet, reddish violet.

7 g. per liter.

Angle 27.3'. Depth o to 0.25 mm.

Strong band in yellow and orange.
Transparent to deep red. Strong
absorption from 0.48/1 to 0.605/1 with
maximum near 0.535/1. Increasing
transparency from 0.605/1 into the
red.

125. Rosolane O. (M.) Phenyldiamido-

phenyl-toluphen-azonium chloride.

Similar to fig. 19, pi. 5; No. 591,
S. & J.

Olive-green powder. In solution deep
violet, faint, reddish violet.

9 g. per liter f warmed and filtered).

Angle 35.1'. Depth o to 0.32 mm.

Weak band in the green broadening
out into general absorption on the
red side. Somewhat similar absorp-
tion to that of solution No. 106.
The visible band is definitely V-
-shaped and slopes more at its less
refrangible side than at its blue
boundary. Slight transparency at
0.23/t is followed by a maximum of

125. Rosolane O — Continued.

absorption near 0.27/1. Absorption
ceases about 0.33/1 and begins again
at 0.495/1. The latter band has its
maximum at 0.525/1 and fades into
general absorption around 0.563/1.
The end of the positive slants ap-
preciably, thus emphasizing the gen-
eral absorption in the orange. Trans-
parent to the red.

126. Nigrosine, soluble. (A.) Sodium salts

of sulphonic acids of spirit nigro-
sines.

Somewhat like figs. 20 and 21 of pis.
5 and 6, respectively ; No. 602, S. & J.

Coal-black, glistening lumps. In solu-
tion blackish blue, dull blue.

Saturated.

Angle 31.2'. Depth o to 0.29 mm.

Very indefinite absorption in the yel-
low and orange. The ultra-violet
absorption is like that of solution
No. 127, while the visible absorp-
tion is similar to that of solution
No. 46. However, the band at
0.528/1 is incomparably weaker than
the corresponding band of solution
No. 46. Absorption rather strong
between 0.20/* and 0.3O/1. From 0.30ft
the absorption decreases to transpar-
ency at o.35/t. Diflferent photo-
graphic emulsions show a weak
band about 0.528/1. Absorption
continues genera! into the red, as is
shown by the appreciable slant of the
end of the negative.

127. Naphthalene Red. Mixture of amido-

naphthyl-naphthazonium chloride and
diamido - naphthyl - naphthazonium
chloride.

Fig. 20, pi. 5 ; No. 614, S. & J.

Dark-brown powder. In solution red,
faint pink.

Saturated (heated).

Angle 31.2'. Depth o to 0.29 mm.

Hazy-edged absorption band in the
green. The visible band extends
from 0.488/1 to o.54S/t with its max-
imum at 0.517/1. The slight inclina-
tion at the red end of the negative
shows appreciable decrease of trans-
parency, between 0.545/1 and 0.63/x,
with increase of thickness of absorb-
ing layer.

128. Alizarine Green B. (D.) Dioxy-

naphthazoxonium sulphonate.
No. 647, S. & J. *

♦Spectrogram too indefinite for reproduction.

COLORING MATTERS.

43

128. Alizarine Creen R — Continued.
Dark-green powder. In solution dark

green, light green.

20 g. per liter (heated and filtered).

Angle 31.2'. Depth 0.26 to 0.55 mm.

General absorption in the violet,
orange, and red. The minimum of
absorption lies in the green, of
course. When the depth was o to
0.2Q mm., the ultra-violet absorption
ended at about 0.355^1. There is no
sharp band in the ultra-violet, but
simply one-sided absorption, decreas-
ing from o.20/i towards the longer
wave-lengths.

129. Columbia Yellow. (A.) Oxidation

products of dehydrothiotoluidine-sul-
phonic acid or of the latter and
primuline together.

Fig. 13, pi. 3 : No. 663, S. & J.

Brownish-yellow powder. In solution
yellow, light yellow.

10 g. per liter f warmed).

Angle 31.2'. Depth o to 0.20 mm.

Weak-edged absorption in violet. Uni-
form absorption from o.20;n to about
0.36/1. Then a steady decrease in
absorption to 0.45/*. Complete trans-
parency from 0.4 q/t to o.63/x.

130. Ouinoline Blue. (G.) No. 664, S. & J.
Glistening, green crystals. In solution

delicate violet, pink.

Saturated (heated).

Angle 0°. Depth 134 mm.

Only the blue and blue-green faintly
transmitted. (No photograph was
taken for the saturated solution.)
When 44 cc. of the saturated solu-
tion was diluted to 90 cc. a strong
band appeared in the yellow and
orange, while the red was freely
transmitted. The ultra-violet absorp-
tion extends to 0.40/* and fades out
about o.42;u.. Weak absorption be-
gins at 0.48/1 and increases to opacity
near 0.55/1. Complete absorption con-
tinues to about 0.607/1. Absorption
decreases rapidly from 0.607/x to
0.63/4. When 44 cc. of the saturated
solution was made up to 112 cc.
and a column 15 cm. was used, no
definite band could be seen, but
only a faint weakening of the
orange. The ultra-violet absorp-
tion was, however, complete as far
as 0.374/1 and vanished near 0.395/1.

131. Ouinoline Yellow, soluble in water.
~ (A.) Quinoline Yellow O. (M.)

Sodium salt of the sulphonic acid
( chiefly d i s u 1 p h o n i c acid ) of
quinophthalone.

Fig. 44, pi. II ; No. 667, S. & J.

Yellow powder. In solution lemon yel-
low, faint yellow.

17.5 g. per liter.

Angle 27.3'. Depth o to 0.25 mm.

Strong band in extreme violet. One-
sided absorption in ultra-violet ends
about 0.33/1. Transparent region
from o.33/t to 0.345/4. A band com-
mences at o.345/t, has its maximum
at 0.40/t, and joins a narrow, com-
panion band at 0.438/t. Maximum
of little band is about 0.448/1 and
complete transparency extends from
0.453/1 to 0.63/1. For a 5-strip nega-
tive the absorption only advanced
to 0.463/t.

132. Indigo Carmine, dry. Sodium salt of

indigotine disulphonic acid.

No. 692, S. & J.

Deep-violet powder. In solution blue,
blue.

10 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Transmits green and yellow. Moder-
ately intense band in the orange-red,
beginning about 0.555/1 and increas-
ing beyond 0.63/1. General absorp-
tion from 0.20/1 to complete trans-
parency at 0.37/1.

133. Acid Magenta S. (A.) Similar to

fig. 53, pi. 14.

Dark-green powder. In solution bluish
red, bluish pink.

10 g. per liter.

Angle 15.6'. Depth o to 0.14 mm.

Strong band in the green with abrupt
edges. Violet, indigo, orange, and
red are transmitted. Similar ab-
sorption to that of solution No. 95.
Partial transparency in the vicinity
of 0.265/t. A comparatively weak,
narrow band has its maximum near
o.295/t, and absorption ceases about
0.325/1. An intense region of ab-
sorption begins at 0.46/t, has its max-
imum at o.535/t, and ends at 0.58/1.
Therefore this region slants more at
the violet border than at the orange
side. The band is very smooth and
round.

44

ATLAS OF ABSORPTION SPECTRA.

134. Alizarine Orange. (Powder 80 per

cent.) (M.)

Fig. 24, pi. 6.

Very deep-purple powder. In solution
dark red, red.

5.83 g. per liter (warmed and filtered).

Angle 27.3'. Depth o to 0.25 mm.

Weak, shadowy band in the green-yel-
low, gradually fading away in the
red. The ultra-violet absorption is
intense and one-sided, and ceases
about 0.39/ix. The visible band be-
gins near 0.48/x, has its maximum at
0.52S/X, and fades into general ab-
sorption about 0.56/x. The end of
the negative slopes to an unusual
extent, showing that the general ab-
sorption is relatively strong.

135. Alizarine Red No. i. 40 per cent. (M.)
Similar to fig. 11, pi. 3.

Yellow paste. In solution deep yel-
low, yellow.

Saturated.

Angle 31.2'. Depth o to 0.29 mm.

Absorption very weak, general, and in-
definite. A few mm. of the solution
show complete opacity. The solu-
tion looks like a milky but yellow
enuilsion. The ultra-violet absorp-
tion is relatively weak, is quite gen-
eral, and fades away to semi-trans-
parency near o.4fi. A slight weak-
ening of transparency around 0.52/x
may be the fault of the sensitized
film. The end of the negative slopes
(|uite enough to indicate continued
absorption in the orange. No visible
absorption in the red.

136. Aurophosphine 4 G. (A.)
Fig. 45. pi. 12.

Keddish-brown powder. In solution
clear yellow, 3'ellow.

1 1.67 g. per liter.

Angle 27.3'. Dejith o to 0.25 mm.

Strong absorption in the violet and
indigo. Absorption decreases from
0.20^ to a maximum at 0.245/* and
then follows a rounded curve to
transparency at 0.305/1. Unusual
transparency from 0.305/t to 0.390/1.
As for /"-nitrosodimethyl aniline, so
here, all the strong lines between
0.324/1 and 0.363/1 are transmitted
with almost no decrease of inten-
sity. A V-shapcd band absorbs
from 0.390/1 to 0.470/A with its max-

136. Aurophosphine 4 G — Continued.

imum at 0.430/t. Transparent from
0.470/4 to 0.63/1.

137. Brilliant Croceine, blue shade. (M.)
Similar to fig. 52, pi. 13.
Bright-red powder. In solution red,

salmon pink.

7 g. per liter.

Angle 25.4'. Depth o to 0.23 mm.

Strong band in blue-green and green.
It slopes more on the blue than on
the yellow border. Similar absorp-
tion to that of solutions Nos. 21 and
43. Absorption decreases from 0.20/x
to a region of partial transparency
in the vicinity of 0.29/1. A sym-
metrical, hazy band absorbs from
about 0.305/1 to 0.385/1. A strong
band absorbs from 0.458/1 to 0.558/1,
with its maximum near 0.518/1.
Transparent to the orange and red.

138. Brilliant Purpurine 10 B. (A.)
Similar to fig. 21, pi. 6.
Grayish-violet powder. In solution red,

bluish red.

5.83 g. per liter (warmed).

Angle 23.4'. Depth o to 0.21 mm.

Shadowy band in the green with gen-
eral absorption in the yellow and
orange. Similar absorption to that
of solution No. 46. Absorption de-
creases from 0.20/1 to a semi-trans-
parent region around 0.29/t. A sym-
metrical, hazy band absorbs from
about 0.30/t to 0.38/1. Another band
begins near 0.48/t, has its maximum
at 052/1, and ends at 0.555/1. The
end of the negative slants at an
angle of about 30°, thus emphasiz-
ing the strong, general absorption
in the yellow-orange.

139. Carthamin.

Similar to fig. 13, pi. 3.

Reddish-brown plates. In solution
brownish red, faint brown.

Concentrated.

Angle 31.2'. Depth o to 0.29 mm.

One-sided absorption in the ultra-
violet. Absorption similar to that
of solution No. 129. Absorption was
strong from 0.20/x to about 0.34/1.
From this wave-length on, the ab-
sorption curve is round and slopes
to o.445/t at the edge of the spec-
trogram farthest from the compari-
.son spectrum. Transparent from
0.445/1 to beyond 0.63/1. The slope

COLORING MATTERS.

45

139. Carthaniin — Continued.

of the blue side of the band is the
same as the corresponding region of
solution No. 119.

140. Columbia Fast Scarlet 4 B. (A.)
Similar to fig. 26, pi. 7.

Red powder. In solution yellowish
red, pink.

5.83 g. per liter.

Angle 27.3'. Depth o to 0.25 mm.

Broad absorption in the blue, blue-
green, and green. The contour is
somewhat hazy. The spectrum is
almost identical with fig. 26 for solu-
tion No. 69, therefore the wave-
lengths are not repeated here.

141. Dianil Orange G. (M.)
Fig. 34, pi. 9.

Brick-red, glistening powder. In solu-
tion yellowish red, yellow.

11.67 &• per liter.

Angle 23.4'. Depth o to 0.21 mm.

Uniform absorption from the blue
border of the green to the extreme
violet and beyond. Except for slight,
wavy regions, the absorption de-
creases almost linearly from o.20;a
to about o.53;tt. At this point it ends
rather abruptly. Transparent from
0.53^ to 0.63/*.

142. Fluoresceine. Tetraoxypthalophenone

anhydride C20H12O5+H2O.

Cinnabar-red powder. In solution faint
yellow.

Saturated (boiled).

Angle 0°. Depth 3.7 mm.

Weak band, in blue and blue-green.
Intense, green fluorescence. Absorp-
tion complete from 0.20/^ to o.25;u
and then decreases to transparency
at o.29/i. Weak absorption ex-
tends from about 0.46/1. to O.505JU..

143. Guinea Carmine B. (A.)
Similar to fig. 20. pi. 5.

Brown powder. In solution red, pink.

Saturated.

Angle 2° 17'. Depth 0.26 to 1.51 mm.

Absorption in green. No lines trans-
mitted between 0.20/* and 0.273/1.
(Non-zero depth of liquid.) Weak
absorption from 0.273/t to 0.33/1.
Transparent from 0.33/t to 0.493/1.
A hazy-edged band extends from
o.493/(, to 0.548/1 with its maximum
at 0.521/1. Transparent from 0.548/1
to 0.63/1. The spectrogram for solu-
tion No. 143 does not slant at the

143. Guinea Carmine B — Continued.

red limit, whereas that for solution
No. 127 does.

144. Orcein.

Suggested by figs. 20 and 21 of pis.
5 and 6, respectively.

Black powder with reddish tinge. In
solution deep red, light red.

Saturated (heated and filtered).

Angle 31.2'. Depth o to 0.29 mm.

Weak, narrow band in the yellow. The
ultra-violet absorption is similar to
that of solution No. 127. The ab-
sorption in the visible spectrum is
.somewhat like that of solution No.
46. However, the band in the yel-
low is very much weaker and nar-
rower for solution No. 144 than for
the corresponding band of solution
No. 46. Strong absorption from
0.20/1 to o.27/t was followed by a
gradual decrease to transparency
near 0.33/1. Transparent froui 0.33/1
to about 0.515/t. A narrow, hazy-
edged absorption band, with its
maximum at 0.525/t, extended from
0.515/1 to 0.542/1 approximately. The
very marked slant of the end of the
spectrogram showed the presence of
comparatively intense, general ab-
sorption in the orange.

145. Soluble Prussian Blue.

Deep-blue, glistening powder. In so-
lution deep blue, blue.

1.76 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Strong absorption in the yellow,
orange, and red. Almost opaque
from 0.20/1 to 0.28/1. Absorption
decreases very gradually from 0.28/*
to 0.38/1. The visible region of ab-
sorption begins at 0.505/1 and con-
tinues to 0.63/1 and beyond.

146. Thiogene Brown S. (M.)
Similar to fig. 11, pi. 3.
Bluish-black lumps. In solution dull

brown, brown.

Saturated.

Angle 27.3'. Depth o to 0.25 mm.

General weakening of all the visible
spectrum except the blue and red.
The solution smells strongly of
hydrogen sulphide. (The odor is
not so marked for the dry dye.)
Similar absorption to that of solu-
tion No. 47. Absorption decreases
very gradually from 0.20/1 to about

46

ATLAS OF ABSORPTION SPECTRA.

146. Thiogene Brown S — Continued.

0.41/^. On both sides of 0.445^ the
absorption is at a minimum. A
very shadowy band absorbs from
0.49/1 to o.545jit. Its maximum is
near 0.523/i. The end of the nega-
tive slants a good deal more than
that of solution No. 47, and thus
points to the absorption in the yel-
low and orange.

147. Thiogene Orange R. (M.)
Similar to fig. 12, pi. 3.

Brown powder. In solution reddish
brown, yellow.

5.83 g. per liter (filtered).

Angle 50.7'. Depth o to 0.46 mm.

Weak absorption in the violet. The
solution has an unpleasant odor. Its
absorption is similar to that of solu-
tion No. 30. Absorption is complete
from o.20;u to o.25/.(, and then de-
creases with a long, gentle curve to
transparency about 0.44^(1. Trans-
parent from o. 445(11 to 0.63^1.

Miscellaneous Absorbing Media.

148. Acetone, Ethyl Alcohol, Methyl .A.lco-

hol. and Water.

Fig. 87, pi. 22.

The depth of the cell was 1.41 cm. for
each of the liquids studied. Especial
care was taken to have the three
organic solvents as nearly anhy-
drous and as pure as possible.

The photographic strip nearest to the
comparison spectrum gives the ab-
sorption of the column of acetone.
The next strip in order corresponds
to ethyl alcohol. The third strip per-
tains to methyl alcohol and the
strip nearest to the numbered scale
is the photographic record for dis-
tilled water.

Acetone absorbed all radiations be-
tween o.20fi and 3282.4 A. U. and
the continuous background as far as
3302.7 A. U. ■

The most refrangible spark line trans-
mitted by the ethyl alcohol had the
wave-length 2265.1 A. U. This
liquid transmitted all the strong
ultra-violet lines, but it absorbed the
continuous background from 0.20^
to about o.275i«,.

The methyl alcohol transmitted very
faintly the strong cadmium line at
2313.0, but no other radiation of

148. Acetone, Ethyl Alcohol, etc. — Cont'd.

wave-length less than 2502.1. The
continuous background in the ultra-
violet, on the contrary, was trans-
mitted somewhat more freely by the
methyl than by the ethyl alcohol.

The distilled water was perfectly trans-
parent to all the radiations in the re-
gion photgraphed.

These results show that even ethyl
alcohol is not without sufficient ab-
sorption in the remote ultra-violet to
make it necessary to take this factor
into account when columns two or
more cm. long are used.

149. Aesculine.

Figr- 73' Pl- 19-

White powder. In solution colorless.

Saturated.

Angle 39.0'. Depth o to 0.36 mm.

No visible absorption. Intense, blue
fluorescence. Absorption decreases
from 0.20/J. to semi-transparency
about 0.261X. Partial transparency
from 0.26/1 to 0.273/i. The band
with which the fluorescence is prob-
ably associated extends from 0.273/1
to 0.363/1 with the maximum near
0.32/1. Complete transparency from
this band to 0.63/1 and beyond.

150. Aluminium Chloride, Calcium Bromide,

and Calcium Chloride.

Fig. 88, pl. 22.

The depth of the cell was 1.41 cm. for
each of the solutions studied. The
photographic strip nearest to the
comparison spectrum gives the ab-
sorption of the calcium bromide so-
lution. The next strip in order corre-
sponds to the aluminium chloride.
The third strip from the compari-
son spectrum pertains to the calcium
salt. The remaining strip shows the
lack of absorption possessed by dis-
tilled water.

The concentrations of the aluminiuin
chloride, calcium bromide, and cal-
cium chloride solutions were, re-
spectively, 2.75, 4.24, and 4.51
normal. The unit used here is the
gram-molecular normal ; that is, i
liter of solution of unit concen-
tration would contain I gram
molecule of the anhydrous salt.

The aluminium chloride solution trans-
mitted faintly all of the strongest

MISCELLANEOUS ABSORBING MEDIA.

47

150. Aluminium Chloride, etc. — Continued.
lines in the remote ultra-violet, but
it absorbed the continuous back-
ground from o.20j«, to about 0.288/11.

The calcium bromide solution trans-
mitted nothino- between 0.20/K. and
2748.7. The intensity of this strong
cadmium line was greatly diminished.
The continuous background began to
be perceptible photographically at
about 0.313^.

The calcium chloride solution trans-
mitted faintly all of the strongest
lines in the remote ultra-violet, but
it absorbed the continuous back-
ground from o.20ju, to about o.28o,u.

Consequently there is no very marked
difference between the absorptions
exerted by the two chlorides. The
bromide, on the other hand, pos-
sesses much stronger absorption in
the ultra-violet region of the spec-
trum.
131. Barium Permanganate.

The absorption is identical with that
of potassium permanganate solu-
tions, having the same concentration
in the MnO^ ions. See No. 179.

152. Calcium Bromide.
See No. 150.

153. Calcium Chloride.
See No. 150.

154. Carborundum and Dia- <^^ a

mond.* Q ^

Fig. 89, pi. 22. c=j c

Eight crystalline plates of $ ^
carborundum and three ^ *
of diamond were fastened § f
to a strip of black paper
in such a manner as to
bridge across different
parts of a long, slit-like
opening in the paper.
The carborundum plates
varied in color from
visible transparency to
deep blue. The carbons
were colorless. The ac-
companying sketch shows
approximately the size,
shape, relative positions,
and distribution of blue of F'g- 7.
the plates, d, e, and / denote the
diamonds. The paper strip was slid
over the slit of the spectrograph, par-
allel to the length of this opening,
and successive exposures were taken.

1 54. Carborundum and Diamond. — Cont'd.
The absorption produced by plates
a, b, c, d, and e was first photo-
graphed, then the absorption of /
and "■, next that of h and i, and
lastly, that of / and k. The spark
and glower exposures were 75 sec.
and 60 sec, respectively.

Plate a was uniformly colored a blue
of moderate intensity. Its absorp-
tion is shown by the photographic
strip, the outer boundaries of which
are numbered i and 2. In cases
where the crystals were not in con-
tact the light passed through be-
tween them and produced narrow
comparison spectra ; for example,
the strip between Nos. 2 and 3.

Plate b was almost colorless with a
frosted surface. Thickness 0.036
mm. Its absorption spectrum is the
strip between 3 and 4.

Plate c had about the same color as
plate a. Thickness 0.173 "im- Its
absorption spectrum is the strip be-
tween 5 and 6.

Plate d was a smooth, colorless car-
bon. Thickness 0.191 mm. Its
spectrum is between 6 and 7. c and
d were practically in contact. This
pair of plates shows how much more
transparent to ultra-violet light pure
carbon is than a colorless plate of
carborundum of comparable thick-
ness. Judging by the negative the
former transmits no light of wave-
length shorter than 2748.7 A. U.,
whereas the latter absorbs everything
shorter than 0.390/14.

Plate e had such an irregular surface
that the light transmitted by it did
not fall upon the sensitized film.
Thickness about 0.191 mm. The
blank between 10 and 11 is due to
translation of the photographic film
between the first and second settings.

Plate / was a diamond with irregulari-
ties running parallel to the slit.
Thickness 0.533 mi''- Spectrum be-
tween II and 12.

Plate g was a deeper blue than any of
the above-mentioned crystals in the
pentagon nearer plate /. The wide
border, extending around four sides
of the blue area, was practically
colorless. Thickness 0.602 mm.

• Kindly loaned by Mr. I,. E. Jewell,

48

ATLAS OF ABSORPTION SPECTRA.

154. Carborundum and Diamond — Cont'd.

Spectrum between 13 and 14. / and
ij contrast diamond, colorless car-
borundum, and blue carborundum
with one another. The blank from
14 to 15 marks the second setting
of the film.

Plate h had a delicate, uniform, blue
tint. Thickness 0.064 mm. Spec-
trum between 16 and 17.

Plate i was a deeper blue than any of
the preceding crystals. Thickness
0.345 mm. Spectrum between 18
and 19. The blank from 19 t<.) 20
corresponds to the third setting of
the photographic film.

The center of plate ;' was as deep in
color as the middle of / and it was
also the thickest plate studied. Thick-
ness 0.693 tfim- Spectrum between
20 and 21.

Plate k was of a delicate blue color of
a slightly deeper hue than plates b
and c, except in the corner nearer ;.
In the latter place it had about the
same tint as plate /;. Thickness
0.097 it^n^. Spectrum between 22
and 23.

155. Chromium Chloride.

Fig- 79. Pl- 20.

In solution very dark green, green.

Saturated.

Angle 50.7'. Depth, from nearly o to
0.46 mm.

Strong absorption in the violet, blue,
orange, and red.

Absorption was complete from o.20/t
to 0.303/1. The boundary of the
ultra-violet band curved around
from 0.303/1* to 0.328/it as the thick-
ness of absorbing layer increased
from its least to its greatest value.
Semi-transparency from 0.328/1 to
0.380/1. A wide, round band, with
its maximum near 0.438/1, absorbed
from 0.380/t to 0.498/1. This is fol-
lowed by fairly complete transmis-
sion from 0.498/i to O.SS5/1. The
orange and red region of absorp-
tion commenced at about 0.555/1.

156. Cobalt Chloride.
Fig. 78, pl. 20.

In solution red, rose-pink.
351-9 S- of anhydrous salt per liter
(2.71 normal).

156. Cobalt Chloride — Continued.
Angle 58.5'. Depth 0.53 to 1.07 mm.
One absorption band in the blue-green

and another in the deep red.* Ab-
sorption was complete from 0.20/1 to
about 0.248/1. The solution was
quite transparent from 0.25/1 to
about 0.495/1. An absorption band,
with its maximum near 0.520/t, ex-
tended from 0.497/t to 0.542/1. Trans-
parent from the boundary of this
band as far as the deep red.

1 57. Cobalt Chloride and Aluminium

Chloride.

Fig. 95, pl. 24.

The plane-parallel cell was kept at the
constant depth of 1.41 cm.

The successive solutions were made up
in the following manner : First, a
chosen volume of the mother-solu-
tion of cobalt chloride was run from
a burette or pipette into a measur-
ing flask. Next, a certain amount
of the mother-solution of aluminium
chloride was run into the same flask
and mixed with the solution of the
cobalt salt. Finally, distilled water
was added to the mixture until the
resulting solution filled up the meas-
uring flask to its calibration mark.
Of course, all the usual precautions
necessary to avoid errors due to
changes in volume on mixing and to
lack of homogeneity were taken.
Each solution of the series was made
up to the same volume and .~on-
tained the same amount of cobalt
chloride. On the other hand, the
mass of the dehydrating agent pres-
ent changed from one solution to
the next.

The photographic strips nearest to the
numbered scale and to the compari-
son spectrum correspond, respec-
tively, to the solutions which con-
tained the least and greatest amounts
of the aluminium salt. The inter-
vening strips succeed one another in
the order of increasing percentages
of aluminium chloride. The con-
stant concentration of the cobalt
chloride in the solutions was 0.271
normal. The concentrations of the
aluminium chloride in the several

♦For exhaustive details see "Hydrates in Aqueous Solution," etc. Harry C. Jones, Publication No. 60 of the
Carnegie Institution of Washington.

MISCELLANEOUS ABSORBING MEDIA.

49

157. Cobalt Chloride, etc. — Continued.

solutions of the series were 0.000,
1. 118, 1.394, 1.676, 1.781, 1.887,
2.096, and 2.459 normal.

The solution which contained no dehy-
drating agent only absorbed the con-
tinuous background from 0.2O/U, to
O.23IJH. The band in the blue-green
extended from 0.503/i to about
0.530/1.

The solution of concentration 2.096,
in the aluminium chloride, absorbed
the continuous background from
o.20fji. to 0.288/x. The iiand in the
blue-green extended from 0.485/x to

0.555M-

The absorption in the yellow and
orange is brought out clearly by the
photographic strip adjacent to the
comparison spectrum. The changes
which the bands in the orange and
red undergo when the amount of
dehydrating agent in the solutions is
increased are pronounced and inter-
esting, but they are too complicated
to admit of discussion in this place.*
Similar changes are brought about
by other dehydrating agents, such
as calcium chloride, for example.

Figure 95 illustrates the fact that the
absorption bands of a colored salt,
so-called, can be widened by the addi-
tion of suitable colorless salts as well
as by simple increase in concen-
tration.

158. Cobalt Chloride in Acetone.

Fig. 90, pi. 23, and fig. 94, pi. 24.

Fig. 90 shows the changes in the posi-
tions of the centers of the regions
of absorption and transmission of
cobalt chloride produced by varying
the solvent. The depth of the cell
was 2.40 cm. Counting from the
comparison spectrum towards the
opposite side of the spectrogram, the
four photographic strips correspond
to solutions of anhydrous cobalt
chloride in water, in absolute methyl
alcohol, in absolute ethyl alcohol, and
in anhydrous acetone, respectively.

The aqueous solution was rosy red.
The methyl solution was purple.
The color of the ethyl solution was
blue with a slight reddish tinge. The
solution in acetone was blue with a

158. Cobalt Chloride in Acetone — Cont'd.

slight greenish tinge. The concen-
trations of the solutions, in the order
named, were, respectively, 0.325,
0.099, 0.097, and o.oio normal.
The aqueous solution absorbed prac-
tically all radiations from 0.20/x to
0.275/x. The blue-green band ab-
sorbed the region between 0.45/i and

0.55/*-

The solution having methyl alcohol for
solvent absorbed all of the ultra-
violet from 0.20/X to near 0.39/n. It
then transmitted from 0.39/1 to
0.495/i. The next absorption band
extended from 0.495/n to 0.56/x. The
faintness of the associated photo-
graphic strip shows the presence of
appreciable absorption in the yellow.

Both the ultra-violet absorption and
the adjoining region of transmis-
sion were very nearly the same for
the solution in ethyl alcohol as for
that in methyl alcohol. On the con-
trary, the third strip gives no indi-
cation of return to transparency in
the yellow of the band which ab-
sorbed all of the green.

The acetone solution transmitted the
region between about 0.38/^ and
0.56/1, but absorbed all the other
radiations which could aflfect the
Seed film.

The phenomena in the visible spectrum
were brought out very clearly by
photographing with a Cramer
"Trichromatic" plate. The depth of
the cell was decreased to 2.00 cm.

The aqueous solution transmitted
from beyond the shorter wave-
length end of the plate to 0.46/4 and
again from 0.543/t to beyond 0.625/t
at the other end of the plate.

The solution in methyl alcohol trans-
mitted from 0.387/1 to o.495/t and
again from 0.548/1 to beyond 0.625/1.
The intensity of the transmitted
light, in the yellow and orange, how-
ever, was not as great for the
methyl as for the aqueous solution.

The solution in ethyl alcohol only trans-
mitted from 0.385/1 to o.497/t.

The solution in acetone only trans-
mitted from 0.373/1 to 0.560/1.

*For exhaustive details see "Hydrates in Aqueous Solution," etc. Harry C. Jones, Publication No. 60 of the
Carnegie Institution of Washington.

5°

ATLAS OF ABSORPTION SPECTRA.

158. Cobalt Chloride in Acetone — Cont'd.

It is thus seen that the photographic
center of the band of absorption in
the green was displaced by about
200 Angstrom units as the solvent
was changed from water to methyl
alcohol. A still greater displacement
was produced by changing from the
one alcohol to the other, the concen-
trations of the two solutions being
very nearly equal.

The empirical data given above serve
to illustrate* the general fact that
the position and character of a
given region of absorption or of
transmission of a chosen colored
salt can be varied, in general, over
wide ranges by suitable changes in
the solvent used.

Fig. 94 shows the way in which the
limits of absorption change when
water is added to solutions of anhy-
drous cobalt chloride dissolved in
absolute acetone. The depth of the
cell was 2 cm. The solutions were
made up in the following manner :
A certain arbitrary volume of water
was poured into a measuring flask
and then the flask was filled up to
its calibration mark by running into'
it from a burette the recjuisite amount
of a mother-solution composed of
anhydrous cobalt chloride and abso-
lute acetone. When water is gradu-
ally added to such a mother-solution
the resulting liquid changes by de-
grees from deep blue through light
blue and then through an almost
colorless condition to faint pink.

The percentages by volume of the
water in the solutions under consid-
eration were, o, 2, 4, 6, 8, 10, and 12.
The concentration of the mother-
solution was 0.015 normal.

The photographic strip nearest to the
comparison spectrum corresponds to
the solution which was anhydrous.
The next strip pertains to the solu-
tion which contained 2 per cent of
water, and so on, across the entire
spectrogram. The mother-solution
absorbed completely all radiations
between 0.20/n and 0.333^11. The con-
tinuous background was very much
weakened as far as about 0.361/x.
The solution transmitted freely

158. Cobalt Chloride in Acetone — Cont'd.

from this wave-length to near
0.552/1. A strong absorption band
commenced at 0.552/1 and extended
into the red.
The photographic strip pertaining to
the solution which contained the
smallest measured amount of water
transmitted from 0.333/1 to about
0.566/1. The change in absorption
due to the addition of water to the
anhydrous mother-solution is, there-
fore, more noticeable in the ultra-
violet than in the yellow. The photo-
graphic boundary of the ultra-violet
absorption band changed but little,
as the percentage of water present
in the solutions increased from 2 to
12, and this is due to the intense
ultra-violet absorption of the pure
acetone. (See No. 148.) On the
other hand, acetone possesses no ab-
sorption band in the visible spectrum,
and hence the limits of transmission
in the green and yellow, as shown
by the several strips of the spec-
trogram, represent correctly the
changes in absorption consequent
upon the addition of successive in-
crements of water.

I S9- Cobalt Chloride in Ethyl Alcohol.
See No. 158.

160. Cobalt Chloride in Methyl Alcohol.
See No. 158.

161. Cobalt Glass.
Fig. 85, pi. 21.

.\ plane-parallel sheet of ordinary blue
cobalt-glass was ground to the form
of a wedge and then polished. A
prism of colorless glass was at-
tached at the sides to the cobalt prism
with its refracting edge parallel to
that of the colored glass. The two
wedges were in contact over their
hypothenuse planes, and hence the
outer plane surfaces were nearly
parallel. The object in using the
colorless glass wedge was, obviously,
to correct for the dispersion of the
cobalt-glass prism. The lack of
agreement between the contiguous
edges of the two photographic strips
shows that the angle of the color-
less prism ought to have been at
least twice as large as that of the
blue prism. The angle of the cobalt-

*See also No. 165.

MISCELLANEOUS ABSORBING MEDIA.

51

161. Cobalt Glass — Continued.

glass wedge was approximately 9°.
The compound system absorbed all
the ultra-violet from 0.20/i to 0.325/i.
The boundary of the ultra-violet
band does not curve or slant very
nuich with reference to the long axis
of the spectrogram because of the
absorption of the colorless glass in
this region of the spectrum. The
cobalt-glass transmits from about
0.327/x to o.497ja. Beginning at
0.497/1* a region of absorption ex-
tends into the red. The most re-
frangible band in this region has its
maximum near 0.52/j,. The mini-
mum of absorption between the band
just mentioned and the less refran-
gible, neighboring band is at wave-
length o.^Gofi. The band in the
orange extended into the red beyond
the field of view of the spectrograph.
These results were tested by using
a red-sensitive photographic plate.

162. Cobalt Sulphate.
Similar to fig. 78, pi. 20.

Reddish crystals. In solution red, sal-
mon pink.

Saturated.

Angle about 6°. Depth o to about 3.2
mm.

Rather weak absorption in the blue-
green. All of the strongest ultra-
violet lines were transmitted. The
continuous background was absorbed
from 0.20/H to about 0.255/n,. The
band in the blue-green extended
from 0.505/1 to 0.525/x with its center
near 0.5x5/1.

163. Copper Chloride.
Fig. 77, pi. 20.

Dark-green crystals. In solution dark
green, yellowish green.

534.7 g. of anhydrous salt per liter
(3.98 normal).

Angle 19.5'. Depth nearly o to 0.18 mm.

Intense absorption in the red. The
solution was remarkable for its
strong absorption of the ultra-violet
radiations. Absorption was complete
from o.20/ii to 0.32/n at the thinnest
part of the wedge. The end of this
band curved around from 0.32/1 to
0.40/1. Transmission was complete
from about 0.40/1 to the orange.

164. Copper Chloride and Calcium Chlo-
ride.
Fig. 92, pi. 23.

The plane-parallel cell was kept at the
constant depth of 1.41 cm. The
several solutions were made up as
explained under No. 157, which see.
The photographic strips nearest to
the numbered scale and to the com-
parison spectrum correspond, re-
spectively, to the solutions which
contained the least and greatest
amounts of the calcium salt. The
intervening strips succeed one an-
other in the order of increasing per-
centages of calcium chloride. The
constant concentration of the cop-
per chloride in the solutions was
0.398 normal. The concentrations
of the calcium chloride in the sev-
eral solutions of the series were
0.000, 0.271, 0.541, 0.812, 1.082,
1.353, 1-624, 1-894, 2.165, 2.435,
2.706, 2.977, 3-247- 3-518, 3-788, and
4.041 normal. The addition of cal-
cium chloride to an aqueous solution
of copper chloride changes the color
of the latter from clear blue, through
green, to yellowish green, due to the
presence of an absorption band in
the red* and to the encroaching of
the ultra-violet band upon the violet
and blue.

The solution which contained only
copper chloride absorbed all radia-
tions from 0.20/1 to about 0.361/1.
The solution which contained the
greatest amoiuit of the dehydrating
agent absorbed all radiations from
0.20/A to about 0.509/1. Hence, the
ultra-violet region of absorption
widened by about 1480 Angstrom
units when the concentration of the
calcium chloride was increased from
0.000 to 4.041 normal. The spec-
trogram shows clearly how the suc-
cessive increments of absorption de-
creased as the concentration of the
calcium salt increased in arith-
metical progression. Other dehy-
drating agents, such as aluminium
chloride, for example, produce sim-
ilar changes in the limits of ab-
sorption.

♦For exhaustive details see " Hydrates in Aqueous Solution,"
Carnegie Institution of Washington.

etc. Harry C. Jones, Publication No. 60 of the

52

ATLAS OF ABSORPTION SPECTRA.

165. Copper Chloride in Acetone.

Fig. 91, pi. 23, and fig. 93, pi. 24.

Fig. 91 shows the changes in the posi-
tions of the ends of the regions of
absorption and transmission of cop-
per chloride produced by varying the
solvent. The depth of the cell was
1.50 cm. Counting from the com-
parison spectrum towards the oppo-
site side of the spectrogram, the four
photographic strips correspond to
solutions of anhydrous copper
chloride in absolute acetone, in ab-
solute ethyl alcohol, in anhydrous
methyl alcohol, and in water, re-
spectively. The acetone solution was
brownish yellow. The ethyl solution
was dark green. The color of the
methyl solution was yellowish green.
The aqueous solution was blue. The
concentrations of the solutions, in
the order named, were, respectively,
0.022, 0.321, 0.283, and 0.795 normal.

The aqueous solution absorbed all
radiations from 0.20/x to 0.387/x and
from 0.588/* into the red.

The solution having methyl alcohol for
solvent absorbed all of the ultra-
violet from 0.20/J, to near 0.462/*. It
transmitted from 0.462/1 to beyond
the region of photographic sensibility
of the Seed films.

The solution in ethyl alcohol absorbed
from o.20/i to about 0.515/1 and again
from o.59/t into the red.

The acetone solution absorbed from
0.20/1 to near 0.510/1. It transmitted
from 0.510/1 to beyond the region of
sensibihty of the film used.

These results were supplemented by
the aid of a Cramer "Trichromatic"
plate. A bluish-green, aqueous solu-
tion of concentration 1.590 normal
was substituted for the one referred
to above. The depth of cell and the
concentrations of the three remain-
ing solutions were unaltered. This
photograph showed that the new
aqueous solution transmitted from
o. 434/1 to 0.588/1, the methyl solution
from 0.462/1 to beyond 0.625/i, the
ethyl solution from 0.513/1 to 0.604/4,
and the acetone solution from 0.510/4
to be3-ond 0.625/*.

165. Copper Chloride in Acetone — Cont'd.
The exposures for the Seed film and

the Cramer plate were, respectively,
1.5 and 2 minutes long.

Fig. 93 shows the way in which the
limits of absorption change when
water is added to solutions of anhy-
drous copper chloride dissolved in
absolute acetone. The depth of the
cell was 2 cm. The solutions were
made up as explained under No. 158,
which see.

The percentages by volume of the
water in the solutions under consid-
eration were o, i, 2, 3, 4, 6, and 8.
The concentration of the mother-
solution was 0.022 normal.

The photographic strip nearest to the
comparison spectrum corresponds to
the solution which was anhydrous.
The next strip pertains to the solu-
tion which contained i per cent of
water, etc., across the entire spectro-
gram. The mother-solution ab-
sorbed completely all radiations from
0.20/1 to 0.517/4. The next four solu-
tions had a region of transmission
the center of which was at 0.436/t.
This region was followed by an ab-
sorption band whose middle was dis-
placed towards the ultra-violet as
the amount of water in the solutions
was increased. For the i and 2 per
cent solutions the center of the ab-
sorption band had the approximate
wave-lengths 0.478/* and 0.475/1, re-
spectively. The solution which con-
tained 8 per cent of water absorbed
all radiations from 0.20/1 to about
0.393/t and transmitted from this
wave-length to beyond 0.62/4.

166. Copper Chloride in Ethyl Alcohol.
See No. 165.

167. Copper Chloride in Methyl Alcohol.
Sec No. 165.

168. Diamond.
Sec No. 154.

169. Erbium Chloride.*

Fig. loi, pi. 26. In solution very faint
pink.

Concentrated (filtered).

The solution was poured into a quartz
cell, the ends of which were plane
and parallel. The cell was succes-
sively adjusted to the following

* A specimen from the collection of the late Prof. Henry A. Rowland.

MISCELLANEOUS ABSORBING MEDIA.

53

169. Erbium Chloride — Continued.

depths, viz: 0.83, 1.13, 1.43, 1.73,
2.03, 2.33, 2.63, and 2.93 cm. In
other words, the thickness of the
absorbing layer was increased by 3
mm. between the successive photo-
graphic exposures. As has been
often remarked by other observers,
the solution in question has a very
large number of remarkably narrow
absorption bands.
For the depth of 0.83 cm. all of the
ultra-violet is absorbed from 0.20/*
to the cadmium line at 2880.9, while
for the depth of 2.93 cm. transmis-
sion begins near 0.300/11. The wave-
lengths of the maxima of the ab-
sorption bands, and the essential
characteristics of the bands, as ob-
tained directly from the original
negative, are as follows: 0.325/1,
0.35O/11, strong with a broad penum-
bra on both sides; 0.3555/x, faint;
0.3645/1, strong; 0.3662/t, faint com-
panion of the last; 0.3766/1, nar-
row and faint; 0.3792/1, strong and
sharp; 0.3875/4, faint, diffuse band
shading off gradually towards the
red ; 0.405/1, weak and sharp ;
0.4075/1, weak ; 0.416/1, faint, dif-
fuse band shading off towards the
red ; 0.419/1, faint ; 0.422/t, faint and
narrow ; 0.427/1, extremely faint
and diffuse band; 0.4425/1, faint;
0.450/1, comparatively strong and
narrow with a very faint com-
panion at the more refrangible side
and with a broad, hazy band near
the opposite edge ; 0.4675/1, very
faint; 0.4725/t, very faint and dif-
fuse ; 0.480/4, extremely faint ;
0.485/1, weak ; 0.4875/t, compara-
tively strong and narrow ; 0.491/1,
wide, hazy band shading off to-
wards the red; 0.5186/1, weak and
narrow ; 0.5205/1, narrow ; 0.5235/1,
strong and narrow ; 0.5365/1, weak
and broad ; and 0.5413/1, weak with
a broad, diffuse companion on the
side nearest to the red.

170. Ethyl Alcohol.
See No. 148.

171. Glycerine.

A plane-parallel layer of glycerine
13.5 mm. deep absorbed all light
of wave-length less than 0.25/1 and
it produced a general weakening

171. Glycerine — Continued.

of the continuous background as
far as about 0.33/t. The exposure
lasted for 1.5 minutes.

172. Litmus.

Figs. 83 and 84, pi. 21.

In solution blue and red for the
neutral (or alkaline) and acid con-
ditions, respectively.

Saturated.

Angle, about 6° for both cases.
Depth o to 3.2 mm., approximately,
for fig. 83.

The absorption of the blue solution
is suggested by fig. 83. Absorp-
tion was practically complete from
0.20/1 to about 0.28/1. From this
wave-length the absorption band
followed a gentle slope to about
0.42/1 for the greatest depth of so-
lution. A region of partial trans-
parency extended from 0.42/1 to
near 0.496/1. A band of absorption
began at 0.496/1 and had its max-
imum approximately at 0.53 i/i.
The spectrogram indicates the ex-
istence of intense absorption in the
orange and red.

Fig. 84 gives the photographic record
obtained with an acid solution of
litmus. This solution absorbed
the greater part of the ultra-violet
region just as the neutral solution
did. On the other hand, the acid
solution exerted general absorp-
tion in the violet and blue, where-
as the neutral solution, of the same
depth, transmitted the light of
these colors. The maximum of
the band in the green was at 0.515/1
for the red solution. The displace-
ment of this maximum from 0.53 i/i
to 0.515/1 was probably exaggerated
by the variations of sensibility of
the photographic films for radia-
tions of different wave-lengths.
Fig. 84 recorded only weak ab-
sorption in the yellow-orange. Red
was transmitted.

173. Methyl Alcohol.
See No. 148.

174. Neodymium Ammonium Nitrate.
Figs. 96, 97, and 98, pi. 25.
Pink crystals. In solution pink.
Concentrated (filtered).

For fig. 96 the solution was poured
into a quartz cell the ends of

54

ATLAS OF ABSORPTION SPECTRA.

174. Neodyniium Ammonium Nitrate —
Continued.
which were plane and parallel.
The cell was successively adjusted
to the following depths, viz : 0.53,
0.83, 1. 13, 1.43, 1.73, 2.03, 2.33,
and 2.63 cm. In other words, the
thickness of the absorbing layer
was increased by 3 mm. between
the successive photographic ex-
posures. As has been often re-
marked by other observers, the so-
lution in question has a large num-
ber of unusually narrow absorption
bands, some of which are very in-
tense and persistent.

For the depth of 0.53 cm. all of the
ultra-violet is absorbed from o.20/t
to the zinc line at 3302.7, while for
the depth of 2.63 cm. only very
faint transmission obtains in the
immediate vicinity of 3407.7 A. U.
The general characteristics of the
most intense bands can be readily
seen by referring to fig. 96, hence
it will suffice to give the approxi-
mate wave-lengths of the absorp-
tion bands which were recorded
by the original negative.

The centers of the bands were at
0.347/i, o.350;a, 0.355^^, 0.381JH, very
faint ; 0.418;^, faint ; 0.4275/x, sharp ;
0.433/^. very faint; 0.4437/*. dif-
fuse ; 0.461/i, faint and diffuse ;
0.4695^^, 0.4755^, faint; 0.4823/x,
0.S087/X, 0.51121H, with a hazy
boundary at the less refrangible
side; o.520yu, 0.5225/i, broad and in-
tense ; 0.5324/x, faint ; o.577S/i, broad
and intense, and 0.5925/u,, faint and
diffuse.

Fig. 97 shows the absorption of the
same solution when placed in the
wedge-shaped cell. The angle of
the liquid wedge was 1° 18' and
the depth increased linearly from
0.71 mm. to 1.24 mm. Except for
the transmission of the strong
metallic lines at 2558.0, 2573.1, and
2748.7, the ultra-violet absorption
is practically complete as far as
0.3250/i. The negative for fig. 97
recorded very faintly all of the ab-
sorption bands given above except
the ones at 0.347/1, 0.350/i, 0.381/*,
0.418/1, 0.461, and 0.5324/4.

174. Neodymium Ammonium Nitrate —

Continued.
The angle of the cell was 39' for fig.
98, so that the thickness of the
absorbing layer varied from about
o to 0.36 mm. Absorption was
complete from o.20/i to 0.237/1. The
boundary of this region of ab-
sorption curved around rather
abruptly from 0.237/1 to 0.250/4 as
the depth of solution increased
from its least to its greatest value.
Transmission by the deepest part
of the liquid wedge was weakened
somewhat from 0.277/1 to 0.308/1.
Only the intense absorption band
at wave-length 5225 A. U. was re-
corded by the negative.

175. Nickel Nitrate.
Fig. 81, pi. 21.

Green crystals. In solution green,
light green.

Saturated.

Angle, about 6°. Depth o to 3.2 mm.,
approximately.

Strong absorption in the orange and
red, also weaker absorption in the
extreme violet. The absorption
was nearly complete from 0.20/1
to about 0.312/4. The end of this
region of absorption curved
around from 0.312/1 to 0.326/1 with
increasing depth of solution. Un-
usual transparency from 0.326/x to
0.374/4. A symmetrical absorption
band, with its maximum at 0.391/t,
extended from 0.374/1 to 0.408/4.
Transmission was complete from
this point as far as the absorption
band in the orange. The sloping
end of the spectrogram calls atten-
tion to absorption in the orange.

176. Nickel Sulphate.
Fig. 82, pi. 21.

Green crystals. In solution green,
pale green.

Saturated.

Angle, about 6°. Greatest depth, 3.2
mm., approximately. Absorption
in the extreme violet, orange, and
red. Using the faint comparison
spectrum as a standard of com-
parison, it becomes evident that
the solution was remarkably trans-
parent to the ultra-violet radia-
tions from 0.226/4 to about 0.365/4.
A symmetrical absorption band,

MISCELLANEOUS ABSORBING MEDIA.

55

176. Nickel Sulphate — Continued.

with its maximum at 0.391/x, ex-
tended from 0.367/14 to 0.415/*.
Transmission was complete from
this point as far as the absorption
band in the orange. A comparison
of figs. 81 and 82 is very sugges-
tive. Both spectrograms show the
same band at wave-length 0.391/*,
but the ultra-violet absorption ex-
erted by the nitrate is entirely dif-
ferent from that shown by the sul-
phate.

177. Picric Acid. 'Hj^
Fig. 86, pi. 22.

Yellow crystals with greenish hue.
In solution yellow, pale yellow.

Concentration unknown.

Angle 50.7'. Depth o to 0.46 mm.

Hazy band in the violet extending
into the ultra-violet. Absorption
decreased gradually from 0.20/1 to
partial transparency at 0.275/1.
Semi-transparency from 0.275/1 to
0.300/i. A band of absorption, with
hazy contour, extended from about
0.300/1 to 0.400/t, its maximum being
near 0.35/1.

178. Potassium Chromate.
Fig. 80, pi. 20.

Yellow crystals. In solution yel-
low, faint yellow.

Very dilute.

Angle 50.7'. Change in depth 0.46
mm.

Absorption in the extreme violet ex-
tending into the ultra-violet. The
most refrangible absorption band
only extends from beyond 0.20/1 to
0.226/1. The solution is noticeably
transparent to all radiations from
2265.1 A. U. to 2321.2 A. U., inclu-
sive of these limits. An intense
band extends from 0.227/1 to 0.300/1.
This is followed by a region of al-
most complete transparency, the
middle of which is near 0.316/1. A
strong band of absorption extends
from 0.332/1 to 0.406/1 with its max-
imum at 0.369/1.

179. Potassium Permanganate.
Figs. 74 and 75, pi. 19.
Grayish-brown crystals with violet

reflex. In solution deep violet,
violet.

179. Potassium Permanganate — Continued.

16.67 S- P^^ liter.

Angle 27.3'. Depth o to 0.25 mm.

Five distinct bands clearly visible
in the green with a very faint com-
panion on the blue side. The cen-
tral band of the five is a little
more intense than its less re-
frangible neighbor. Light from the
spark decomposes the potassium
permanganate so rapidly, with the
formation of innumerable small
bubbles, that the exposures had
to be made as follows : 1st. Expose
to spark for 25 seconds. 2d. Re-
move cell from spectrograph and
clean away the bubbles. 3d. Re-
place the cell and make another
exposure for 25 seconds, etc., three
times for each distinct strip of the
spectrogram. The absorption at
0.20/1 is weak and decreases to
transparency near 0.25/1. Unusual
transparency from 0.25/1 to 0.29/1.
This fact is brought out in a half-
dozen spectrograms of the region.
A band of absorption extends
roughly from 0.29/1 to 0.36/1 with
its maximum at the center. The
transparency increases to com-
pleteness and continues to 0.483/1.
The wave-lengths of the 7 photo-
graphic bands are 0.457/1, 0.472/1,
0.488/*, 0.505/1, 0.525/1, 0.545/1,
and 0.570/1. (Only 5 bands show on
the complete spectrogram.) In
decreasing order of intensity the
three strongest bands are 0.525/1,
0.505/* and 0.545/*.

An effort was made to detect the 8
bands given by Formanek,* but
the conditions were not favorable
to recording more than seven
bands. Formanek's wave-lengths
are "571.0, 547.3 (Hauptstreifen),
525.6, 505.4. 487.0, 470.7, 454.4,
and 439-5-"

The negative for fig. 75, pi. 19, shows
the seven bands. The solution
was practically saturated since it
contained 50 grams per liter at
room temperature. Here the ultra-
violet absorption extends as far as
0.39/1. For concentrations from
16.67 to 50 grams per liter, and for

*SeeJ. FormSnek, "Die qualitative Spectralanalyse auorganischer Korper," p. 59.

56

ATLAS OF ABSORPTION SPECTRA.

179. Potassium Permanganate — Continued.

the method used, the bands do not
shift at all* Trichromatic plates
were used to see if any photographic
bands less refrangible than 0.570^
could be recorded. No evidence of
the existence of such bands was pre-
sented.

180. Praseodymium Ammonium Nitrate.
Fig. 100, pi. 26.

Yellowish-green crystals. In solu-
tion yellowish green.

Concentrated (filtered).

The solution was poured into a
quartz cell, the ends of which were
plane and parallel. The cell was
successively adjusted to the fol-
lowing depths, viz: 0.73, 1.03, 1.33,
1.63, 1.93, 2.23, 2.53, and 2.83 cm.
In other words, the thickness of
the absorbing layer was increased
by 3 mm. between the successive
photographic exposures.

The solution is remarkable for the
comparative narrowness and great
intensity of its absorption bands.
Absorption was complete from
0.20/X to about 0.333/* and 0.343/i,
respectively, for the least and
greatest depths of solution investi-
gated. The centers of the four in-
tense bands which fell within the
region of sensitivity of the Seed
emulsion were at wave-lengths
o.4445/t, 0.4685/x, 0.4820/1, and
0.590/i. The least refrangible side
of the band at 0.590/t does not ap-
pear in fig. 100 because the band
came very near the limit of sensi-
bility of the photographic film em-
ployed.
181. Sodium Bichromate.

Suggested by fig. 14, pi. 4.

Orange-red crystals. In solution
yellow, pale yellow.

Very dilute solution.

Angle 50.7'. Depth o to 0.46 mm.

181. Sodium Bichromate — Continued.

The spectrogram differs from fig. 14
in having the ultra-violet absorp-
tion curve displaced bodily to-
wards the region of the shortest
wave-lengths. Absorption was
practically complete from o.20/t to
about 0.27/i, for all depths. At the
thickest part of the liquid wedge
absorption was complete from o.20/i
to 0.40/1, but both the photographic
strip adjacent to the comparison
spectrum and the one in the mid-
dle of the spectrogram recorded a
comparatively narrow band of
semi-transparency, the center and
maximum of which was near
0.318/*. This was followed by a
strong, round absorption band
whose maximum was at 0.36/1. In
other words, there were two round,
ultra-violet bands of absorption
which coalesced at the wave-
length 0.318/4. Transmission was
complete from 0.40/1 to 0.63/*.

182. Sodium Nitroprussid.
I'ig. 76, pi. 19.

Garnet crystals. In solution reddish
brown, light brown.

Saturated.

Angle 1° 45'. Depth o to 0.96 mm.

Weak absorption in violet. Light
from the spark decomposes the
solution at the very beginning of
illumination so that the method
used for photographing the ultra-
violet absorption of the perman-
ganates was not applicable. This
difficulty was not overcome. Ab-
sorption decreases to about 0.38/4,
then increases to a weak maximum
near 0.396/1, and finally decreases
to transparency at 0.428/1. No
selective absorption from 0.43/1 to
0.62/i.

183. Water. See No. 148.

*See H. Kayser."Handbuch der Spectroscopic," v. iii, p. 415.

alphabetical list of absorbing media.
Alphabetical List of Absorbing Media.

57

Page

Acetone

Acid Brown

Acid Green, cone'

Acid Magenta S

Acid Rosamine A

Aesculine

Alizarine Blue S

Alizarine Brown ■

Alizarine Green B

Alizarine Orange. (Powder 80%

Alizarine Red No. i, 40% ,

Alizarine Red S

.Ukali Blue 6 B

.\luminium Chloride

.\midonaphtholdisulphonic

Acid H

Anthracene Red

Anthracene Yellow C

Auramine O

Aurantia

Aurophosphine 4 G

Azo Acid Yellow

Azo Blue

Azo Coccine 2 R

Azo Rubine S

Azo Yellow, cone'

Barium Permanganate

Benzoazurine

Benzopurpurine B

Benzopurpurine 6 B

Benzopurpurine 10 B

Biebrich Scarlet

Bismarck Brown

Blue Black

Bordeaux B

Brilliant Congo R

Brilliant Croceine, blue shade..

Brilliant Orange G

Brilliant Purpurine 10 B

Brilliant Purpurine R

Calcium Bromide

Calcium Chloride

Carborundum

Carthamin

China Blue

Chromium Chloride

Chromotrope 6 B

Chrysamine G

Chrysoidine

Cloth Red G

Cloth Red 3 G A

Cloth Red O

Cobalt Chloride

Cobalt Chloride and Aluminium
Chloride

Cobalt Chloride in Acetone ....

46
27
35
43
38
46

41
41
42
44
44
41
37
46

21

31
29

34
21

44
25
32
23
26

25

47

33
31
31
33

28

29
29

23
32
44
23
44
32
47
47
47
44
37
4S
22

30
22

28
28
28
48

48
49

Cobalt Chloride in Ethyl Alcohol. 50

Cobalt Chloride in Methyl Alcohol 50

Cobalt Glass 50

Cobalt Sulphate ' 51

148

42
86

133
106

149
120
iiS
128
134
135
119

97
150

I
62

53
82
8
136
31
72
14
35
31

151

75
65
64

74
49
54
52
19
67

137

15

138

69

152

153

154

139

99

155

13

57

12

45

47

46

156

157
158

159

160

161
162

22

87

12

46

5

19

7

19
73
28

6

24

19

2

7

3

6

20

24
I 23
I 24
]23
I 24
I 23
i 24

Fig.

14
72
88

43
39
45

74

75

31

26

89

71
79

8

7
25
II
21
78

95
90

94
90

94
90

94

85

Page

Coccinine B

Columbia Fast Scarlet 4 B

Columbia Yellow

Congo Brown G

Congo Brown R

Congo Corinth

Congo Corinth G

Congo Orange G

Congo Orange R

Congo Red

Congo Rubine

Copper Chloride

Copper Chloride and Calcium
Chloride

Copper Chloride in Acetone. . . .

CopperChloride in Ethyl Alcohol,

Copper Chloride in Methyl )

Alcohol J

Coralline Red

Cresotine Yellow G

Crystal Ponceau 6 R

Crystal Violet

Curcumeine

Curcumine S

Cyanosine

Dahlia

Deltapurpurine 5 B

Diamine Black B O

Diamine Green B

Diamine Red B

Diamine Red 3 B

Diamond

Dianil Orange G

Dianil Yellow R

Emerald Green

Emin Red

Eosamine B

Eosine a I'alcool

Eosine, bluish

Eosine, yellowish

Erbium Chloride

Erika B

Erythrosine

Ethyl Alcohol

Ethyl Violet

Fast Acid Violet A 2 R

Fast Acid Violet B

Fast Brown 3 B

Fast Green O ,

Fast Red A

Fast Red, extra

Fast Yellow

Fluoresceine

Fuchsine

Fuchsine S

Galleine

Glycerine

Guinea Carmine B

Heliotrope 2 B

Indigo Carmine, dry

Janus Green

No.

20
140
129

77

78
71
60

56
63
59
61
163

164
165

166

167

100
58
18
90
30
81

113
89
66
73
76
66
68

168

141
40
84

23

21

109

III
108
169
22
112
170

91

105

104

38

79

34

36

9

142

87

95

116

171

143
124
132

24

PI.

20

23
(23
I 24
(23
I 24
(23
I 24
13

Fig.

13

35
36
35

23
33

77

92
91
93
91
93
91
93
49

3

12

10

37

5

18

18

69

16

61

22

89

9

34

8

29

13

52

5

17

15

58

26

lOI

15

57

15

59

22

87

16

64

16

63

7

27

12

"48

14

53

17

68

58

ATLAS OF ABSORPTION SPECTRA.
Alphabetical List of Absorbing Media. — Continued.

Janus Red B

Light Green F S

Litmus

Malachite Green

Metanil Yellow

Methyl Alcohol

Methyl Blue

Methyl Eosine

Methyl Green , .

Methyl Green GO

Methyl Orange III

Methyl Violet 6 B

Mordant Yellow O

Naphthalene Red

/3-Naphtholdisulphonic Acid G .

Naphthol Green B

Naphthol Yellow

Naphthol Yellow S

Naphthylamine Brown

Neodymium Ammonium Nitrate.

Neutral Red

New Coccine

New Coccine O

New Magenta

Nickel Nitrate

Nickel Sulphate

Night Blue

Nigrosine, soluble

/-Nitraniline. (Powder, "extra. "). .

o-Nitrobenzaldehyde

/-Nitrosodimethylaniline . ...

Orange G

Orcein

Phenosafranine

Phloxine

Page

No.

PI.

Fig.

28

44

85

172

35
53

21

(83

(84

34

S3

25

32

10

40

53

173

22

87

37
39
36

98

. . . .

94

12

47

36

2'i

93

28

II

41

36

92

17

66

27
42

39
127

5

20

f 2

21

2

I

\ 5

34

80

3

10

21

7

II

42

21

7

II

42

25

33

(96

53

174

25

J97
I 98

41

121

26

37
34

26

7

27

35

88

13

50

54

175

21

81

54

176

21

82

37
42

lOI

126

3

4

5

21

I

3

22

10

8

30

45
41

144
122

14

54

40

"5

15

60

Phosphine

Picric Acid

Ponceau B O, extra

Ponceau 2 G

Ponceau 2 R

Ponceau 3 R

Ponceau 4 R B

Ponceau 6RB

Potassium Chromate

Potassium Permanganate

Praseodymium Ammonium

Nitrate

Quinoline Blue

Quinoline Yellow O

Quinoline Yellow, sol. in water.

Red Violet 5RS

Resorcine (techn. pure)

Resorcine Brown

Rhodamine B

Rosazurine B

Rose Bengal

Rosolane O

Safranine

Sodium Bichromate

Sodium Nitroprussid

Soluble Prussian Blue

Thiogene Brown S

Thiogene Orange R

Trop;eoline O

Tropaeoline OO

Tropaeoline OOO No. i

Tropa^oline OOO No. 2

Uranine

Vesuvine

Victoria Blue 4 R

Water

Wool Black

Page No. PI. Fig

41
55
27
22

23
23

28
29

55
55

56
43
43
43
37
21
27
38
32
40
42
42

117
177

43
II
16
17

48
51

178

179

180
130
131
131

96
6

41
103

70
114
125
123

56 181
56 182
45 I 145
45 146

147
25
29
26
27

38 107

55
102

183
50

16

19

32
86

55
51
56

80

■74
.75

44
44
62

4
38
65

76

{;.

5

6

7
70

87
67

ATLAS OF ABSORPTION SPECTRA.

59

For convenience in identifying the stronger spark lines, fig. 99, pi. 25, is given.*
The numbers on this positive correspond to those preceding the wave-lengths belov/.
The wave-lengths were derived from the two following sources:

"An Introduction to the Study of Spectrum Analysis," by W. M. Watts. Long-
mans, Green & Co., 1904.

"Measurements of the Wave-lengths of Lines of High Refrangibility in the Spectra
of Elementary Substances." Hartley and Adeney. From the Philosophical Transac-
tions of the Roj'al Society. Part I, 1884.

3
4
5
6

7
8

9
10
II
12
13
14
15
16

17

18

19
20

2X
22
23
24
25
26

W.-l.

2024.
2060
. 2062
2099
2I3S.
2144.
2194.
2239.
2265.
228S
2306.

2313'

2321.
2329.
2502,
2558,

2573
' 2710
.2712,
2748,
2770
2801

2837'
2880.
2980
3007.

3035
3072

I 3076

Radia-
tor.

2 Zn.

.0 Zn.

,3 Zn.

.5 Cd.

,7 Cd.

,9 Cd.

,1 Cd.

,1 Cd.

,7 Cd.

,0 Cd.

2 Cd.

3 Cd.
.1 Zn.

Zn.

Cd.

Air.

Zn.

Cd.

Zn.

Zn.

Cd.

Cd.

Cd.
o Air.
.g Zn.

.0 I

Radia-
tor.

27.
28.
29.
30-
31-

32. {

33. {

34-
35-

36. {

37-

3S.{

39-
40.
41.
42

Cd.
Cd.
Cd.
Zn.
Zn.

|3°72.2U„.

1 3076.0 I

43. {

44.
45-

46. {

47-
48.
49.

3133.3
3250-5
3261.2
32S2.4
3302.7

33^9-3 I Air.

3331.5 I

3345.1 I Zn.
3345-5 i

3407.7 Cd.
3436.9 Air.
3466.3 1 p ,

3467.8 ( '-''■
3530.0 Cd.

3610.7 1. Cd.
3613.0 I
3682.6t

3712.2 Air.

3726.6 Air.

3749.8 Air.

3839-3 \
1.7)

Air.
Air.

384
3881.9
3919.2 Air,
3954.S I Air
3956.2 (
3972.5 Air,
3995.1 .\ir,
4041.4 Air,

No. W.-l.

I 4070.C

50. j 4072..]
I 4076.1

51. 4119.
„ } 4132.
^^- U133.
53. 4145.

54- -^

^^ 1 4153-

f422S.

55- \ 4236-
I 4241-

56. 1^316-
^ 1 4318.

57. 4349

58. 4367,

59. 4415

Radia-
tor.

Air.

Radia-

I]''

Air.
Air.

j 4447

60. ,
.4447

61. 4530

62. 4576,

63. 4601,

64. 4607

65
66
67
68

4614
4621
4626
4630.

4
8
8
9 Air.

Air.

Air.

Air.
Air.
.\ir.

Air.

Air.
Cd.
Air.
Air.
Air.
Air.
Cd.
Air.

.1I
2 f

6
o
7

9JAir.
4i

92 t

IN U

70

4649.2

tor.
Air.

71

4680.4

Zn.

72

4722-3

Zn.

73

4S00. 1

Cd.

74

4810.7

Zn.

75

4912.3

Zn.

76

4924.8

Zn.

77

1 5002.7 j Air.
15005.7/

78

5045-7

Air.

79

5086.1

Cd.

80

5116.0

Zn.

153

81

5146.2

Cd.

162

82

5338.6

Cd.

— 2

83

5354.4

Cd.

— 2

84

5379-3

Cd.

85

5497.4

Cd.

182

86

5509.0

Zn.

— 2

87

5541.8

Zn.

192

88

5602.0

Zn.

202

89

5761.8

Cd.

222

90

5961.6

Cd.

232

91

6014.0

Air.

242

92

6035.0

Zn.

— 2

93

6071.8

Zn.

252

94

6144.4

Zn.

262

95

6152.0

Zn.

262

96

6160.4

Cd.

— 2

97

6266.6

Cd.

272

The following table facilitates the finding of the numbers, names, etc., of all the
substances which, have an absorption spectrum more or less similar to that shown by a
selected spectrogram. The third column gives the number of every substance referred
in the text to the plate and figure of the preceding columns.

Plate. Fig.

3
3
3
4
5
5
6
6
6
7
7
8

9
10
10
10

II
12
13
14
19
20
21
22
23
25
26

31
36
37
39
40

33, 63. 79, "6, 118, 135, 146.

31, 147-

39, 139.

181.

19, 61, 105, 125.

126, 143. 144.

126, 138, 144.

71, 72, 73, 75-

38, 44.

70.

59,64,65,66,67,70, 140.

26, 27.

57, 58.

25, 40, 53-

42.

9, 29.

plate.

Fig.

No.

12

46

83, 84, 85.

12

47

93-

13

51

49-

13

52

37, 43, 137.

14

53

133.

14

54

121, 123.

14

55

16, 18, 20, 35, 36

14

56

62.

15

58

no, III.

15

59

114.

16

63

105.

17

66

90.

18

70

lOI.

18

71

98.

20

78

162.

♦The negative was not a single exposure. To stand reproduction the extreme ultra-violet was "favored."
t "Doubtful Origin." J The subscript 2 denotes the second order of spectrum.

ABSORPTION SPECTRA.

PLATE 1.

i^ .01 .60 -Sd .68 .B7 .S6 .55 .St .B3 .82 .51 .^

lIlHlllllUllluil!!'

.» .U M .M .M .»* .W .M .tjl ••?> J).0 .88 .37 .30 .38 .3» .33 Sa .31 .30 .29 .38 .« .36 .38 .3* .M .32 .21 J!0

iii'liinliiiiliiiiliiiiliiiiliiiilniiliiiiliiiiliiiiliiiiliiiiliiiir' ' "' ViiliiiiliiiiliiiiliiiiliiiiliinlaiiliiAiiiiHiiiiiiliinliiiiliimiiliiiwiilin^

FIG. 1.

FIG. 2.

FIG. 4.

FIG. 5.

FIG. 1. SEE NO. 1. AMIDONAPHTHOLDISULPHONIC ACID H.

FIG. 2. SEE NO. 2. /8-NAPHTHOLDISULPHONIC ACID G.

FIG. 3. SEE NO. 5. /'-NITROSODIMETHYLANILINE.

FIG. 4. SEE NO. 6. RESORCINE.

FIG. 5. SEE NO. 2.

HEi-ioTYPC CO., eosroK.

ABSORPTION SPECTRA.

PLATE 2.

.63 .•! .ep .■> .s,8 .v Jta .ss .l^k .^

'llllllllllllll!

.S7 M .S5 .» .Sj3

.51 .BO .te .48 .» .U .»6 .»» .tg M M M .30 .38 .37 .30 .3E .3* .33 .92 .31 .30 .20 .28 .27 .26 .25 .» .23 .22 .21 .20

MMliiiiliiiiliniiiliiniiliiiiliiiiliiiiliiiiliiiiliiiiliiiiliiiiliiin^

FIG. 6.

FIG. 9.

FIG. 6. SEE NO. 11. PONCEAU 2 G.

FIG. 7. SEE NO. 12. CHRYSO'fDINE.

FIG. 8. SEE NO. 13. CHROMOTROPE 6 B.

FIG. 9. SEE NO. 14. AZO COCCINE 2 R.

M6l,IOTvPE CO., a05T0N.

ABSORPTION SPECTRA.

PLATE 3.

82 .81 .60 .19 .58 .67 .M .58 .B> .63 .M .lil .6« .»9 .»8 .57 .tj6 .*6 .»» .«j3 .52 .« M .39 .38 .37 .36 .38 .3* .33 .32 .31 .30 .29 .:

iiiiiliiiiliii

FIG. 10.

FIG. 11.

FIG. 13.

FIG. 10. SEE NO. 80. NAPHTHOL GREEN B.

FIG. 11. SEE NO. 47. CLOTH RED 3 G A.

FIG. 12. SEE NO. 30. CURCUMEINE.

FIG. 13. SEE NO. 129. COLUMBIA YELLOW.

HELIOTTPE CO., BOSTON.

ABSORPTION SPECTRA.

PLATE 4.

.62 *.l t.o pn ■^s

■^S .6* .6J .92 .61 .60 .»» .»e .t7 .»B .*S .»» .10 .li .11 .«) .30 .38 .07 .06 .06 .'M .33 .32 .31 .30 .20 .28 .27 .28 .26 .2* .2,3 .22

21 .20

' ill

FIG. 14.

Mf

^iiq

•■, i

ii

J

FIG. 15,

FIG. 16.

FIG. 14. SEE NO. 119. ALIZARINE RED S.
FIG. 15. SEE NO. 107. URANINE.
FIG. 16. SEE NO. 107. URANINE.

HELiOTYPE CO., BOSTON

ABSORPTION SPECTRA.

PLATE 5.

.62 .ei .6(1

||.|,.|||;||.l|,„l.

FIG. 17.

FIG. 18.

""■'^

FIG. 19.

~r-!MP TTgT ;; ' wmmtTifWr

FIG. 20.

FIG. 17. SEE NO. 109. EOSINE A L'ALCOOL.

FIG. 18. SEE NO. 113. GYANOSINE.

FIG. 19. SEE NO. 106. ACID ROSAMINE A.

FIG. 20. SEE NO. 127. NAPHTHALENE RED.

«ELIOTrPe CO., 30ST0N.

ABSORPTION SPECTRA.

PLATE 6.

.62 .ftl .6,0 .89 .68 .57 .8,6 .5,5 .5* .53 .52 .SI .50 ,40

Uiilllib.J.llhlf'il.turiMlnill'l'.ililli

,U .17 M M .»» .t^ .<|3 M M .a» .as .37 .36 .36 .3» .33 .33 .31 .3.0 .2,9 .28 .2,7 .26 .2,5 .2» .33 .22 .21 .2

FIG. 21.

FIG. 22.

f-'IG, 23.

FIG. 24.

FIG. 21. SEE NO. 46. CLOTH RED O.

FIG. 22. SEE NO. 74. BENZOPURPURINE 10 B.

FIG. 23. SEE NO. 60. CONGO CORINTH G.

FIG. 24. SEE NO. 134. ALIZARINE ORANGE.

KtLIOTYPE CO., B05T0W

ABSORPTION SPECTRA.

PLATE 7.

.62 .(ti m -■■

mil;:

FIG. 26.

isij iiim

FIG. 28.

FIG. 25. SEE NO. 45. CLOTH RED G.

FIG. 26. SEE NO. 69. BRILLIANT PURPURINE R.

FIG. 27. SEE NO. 34. FAST RED A.

FIG. 28. SEE NO. 120. ALIZARINE BLUE S.

HEIIOTVPE CO., tfOSTOH.

ABSORPTION SPECTRA.

PLATE 8.

.02 ei fo '-^

FIG. 29.

FIG. 30.

FIG. 32.

FIG. 29. SEE NO. 23. EMIN RED.

FIG. 30. SEE NO. 10. ORANGE G.

FIG. 31. SEE NO. 15. BRILLIANT ORANGE G.

FIG. 32. SEE NO. 117. PHOSPHINE.

HEUOTYPE CO., BOSTON,

ABSORPTION SPECTRA.

PLATE 9.

.62 .61 .60 ,59 5S ,.i7 .Se .5.5 .H ^'--^

FIG. 33.

FIG. 34.

FIG. 36.

FIG. 33. SEE NO. 56. CONGO ORANGE G.

FIG. 34. SEE NO. 141. DIANIL ORANGE G.

FIG. 35. SEE NO. 77. CONGO BROWN G.

FIG. 36. SEE NO. 77. CONGO BROWN G.

hCLIOTVPE CO., aOSTON

ABSORPTION SPECTRA.

PLATE 10.

.62 fil .60 R9 S8 .=;7 .16 .^5 's» s;l ?i Rl ^0 49 4S ^^ VH \s >» >a IJ >I JO

Kl .29 28 27 .2t> 25 2* 23 2'J 21 .30

FIG. 37

FIG. 38.

FIG. 39.

FIG. 40.

FIG. 37. SEE NO. 81. CURGUMINE S.

FIG. 38. SEE NO. 41. RESORCINE BROWN.

FIG. 39. SEE NO. 8. AURANTIA.

FIG. 40. SEE NO. 32. MET ANIL YELLOW.

MELIOTVPE CO., BOSTOh.

ABSORPTION SPECTRA.

PLATE 11.

?H ^;i vr "1 ^fi Ti \^> »"' i*' 1?^ 1^ >'^ "I ^ 1' ^*' ■'" ■'*' '

FIG. 41.

FIG. 42.

FIG. 43.

FIG. 44.

FIG. 41. SEE NO. 28. METHYL ORANGE III

FIG. 42. SEE NO. 7. NAPHTHOL YELLOW.

FIG. 43. SEE NO. 82. AURAMINE O.

FIG. 44. SEE NO. 131. QUINOLINE YELLOW 0.

HtLIOTYPE CO., aOSTOh.

ABSORPTION SPECTRA.

PLATE 12.

-;l|S .3* .33 .32 .31 .30 .29 .2|8 .27 .38 .26 .21 .'

'I|ll|{||||||||l||l{|linll|ipll|lllllil|llllllluili|inilllll!lllillllllilllililmllny^^

FIG. 47.

FIG. 48.

FIG. 45. SEE NO. 136. AUROPHOSPHINE 4 G.

FIG. 46. SEE NO. 86. ACID GREEN, CONC.

FIG. 47. SEE NO. 94. METHYL GREEN.

FIG. 48. SEE NO. 87. FUCHSINE.

MELIOTVPE CO., BOSTON.

ABSORPTION SPECTRA.

PLATE 13.

.ea .81 .60 .18 .88 .67 .88 .SB .5* .68 .62 .61 .60 M M .^7 .M .*$ .»» .40 .42 .»! M .89 .3^8 .37 .38 .36 .a» .33 .32 ,31 .30 .20 .28 .27 .26 .26 .2* .23 :: Ji -n

;!l||lll|ll|]|llll|li;iki|'il!ilil:|i!!' "T »: :! :i' !llV;:^ii!:i'^ill|i(ll||i!l!|ft

FIG. 49.

FIG. 49. SEE NO. 100. CORALLINE RED.

FIG. 50. SEE NO. 88. NEW MAGENTA.

FIG. 51. SEE NO. 48. PONCEAU 4 R B.

FIG, 52. SEE NO. 21. EOSAMINE B,

hELIOTYPE CO., rlOSTON.

ABSORPTION SPECTRA.

PLATE 14.

.62 .61 .60 .69 .58 .57 .56 5S S» 63 .52 .51 .50 .»9 .tS .17 .W .M .»* M .W .« M .38 .3,8 .37 .36 .36 .3* .33 .93 .31 .30 .2/) .3.8 .27 .3,6 .2JB .2,* .^ .32 .3,1 .2,0

.M .ta .U .« .W .36 .3,8 .37 .36 .35 .3* .33 .93 .31 .S

■'''■'■■ hiliiJiiiititlinlKiiVjiHiiii'iiiiii'iiiiiHihiVil^iiVJrintili'iKiili!'^

FIG. 53.

FIG. 55.

FIG. 56.

FIG. 53. SEE NO. 95. FUGHSINE S.

FIG. 54. SEE NO. 122. PHENQSAFRANINE.

FIG. 55. SEE NO. 17. - 3 R.

FIG. 56. SEE NO. 51. Pu.^>_tiMu 6 R B.

MtLtOTVPE CO., 30ST0N.

ABSO'RPTION SPECTRA.

PLATE 15.

FIG. 57.

FIG. 58.

FIG. 59.

FIG. 60.

FIG. 57. SEE NO. 22. ERIKA B.
FIG. 58. SEE NO. 108. EOSINE, YELLOWISH.
FIG. 59. SEE NO. 112. ERYTHROSINE.
FIG. 60. SEE NO. 115. PHLOXINE.

HELIOTVPt CO., SOSTOn.

ABSORPTION SPECTRA.

PLATE 16.

X.ei .ep .58 .68 .57 .1^ .65 .U .53 .52 .51 .6(1 M .t|8 .kT M M .*i .13 .y .« .M .

.37 .36 .06 .3* .3,3

.20 .28 .27 .26 .25 .2* .23 .22 .21 .21

FIG. 61

FIG. 52.

FIG. 63.

FIG. 64.

FIG. 61. SEE NO. 68. DIAMINE RED 3 B.

FIG. 62. SEE NO. 96. RED VIOLET 5 R S.

FIG. 63. SEE NO. 104. FAST ACID VIOLET

FIG. 64. SEE NO. 91. ETHYL VIOLET.

MELIOTVPE CO., 80ST0N.

ABSORPTION SPECTRA.

PLATE 17.

FIG. 6-.

FIG. 65. SEE NO. 103. RHODAMINE B.

FIG. 66. SEE NO. 92. METHYL VIOLET 6B.

FIG. 67. SEE NO. 50. WOOL BLACK.

FIG. 68. SEE NO. 124. HELIOTROPE 2B.

HELIOTVPE CO., 90STON

ABSORPTION SPECTRA.

CLATE 18.

2 .81 <M »e *« '-: M ^p :>» ^,.
Ill'

»^ » » »;l ». »i

Jl :io 2" 38 .57 .36 .31

'iiiliniliwliiiiliiiil

II .2t

Jinilii

„J

FIG. 70.

FIG. 72,

FIG. 69. SEE NO. 89. DAHLIA.

FIG. 70. SEE NO. 102. VICTORIA BLUE 4R.

FIG. 71. SEE NO. 99. CHINA BLUE.

FIG. 72. SEE NO. 97. ALKALI BLUE 6B.

HELIOTvPt CO., aOSTON.

ABSORPTION SPECTRA.

PLATE 19.

.82 .01 .60 .S8 .58 .67 .56 .55 .5» .63 .62 .51 .50 .49 .48 .17 .46 .45 .44 .43 .42 .41 .40 .39 .38 .37 .36 .35 .34 .33 .32 .31 .30 .29 .28 .27 .26 .26 .24 .23 .22 .21 .20

!i{i{|iiii{{iiiliii{|iiiiJ!iiiiiiiiJiiiili!iiliiiiliiiiiiiiiliiiiliiiilnnliiiiliiiiiiiiili{iiliiiiliii

FIG. 73.

FIG. 74.

FIG. 76.

FIG. 73. SEE NO. 149. AESCULINE.

FIG. 74. SEE NO. 179. POTASSIUM PERMANGANATE.

FIG. 75. SEE NO. 179. POTASSIUM PERMANGANATE.

FIG. 76. SEE NO. 182. SODIUM NITROPRUSSTD.

HELIOTVPE CO., SOSTOft.

ABSORPTION SPECTRA.

PLATE 20.

.S2 .ei .60 .B9 S8 .B7 56 55 .5» .63 .^ .51 50 .«» .U .»T .1

iiiiiniilinilittiiiiiiliiiiliiiiiiiliiiiiiiiiiiiiiiiiiiiiiiii'iiiiiiiiiiiiiliiiiliiiiliiiil

FIG. 78.

»

^H

1 ^^1

I ^Hl

1

l^l^^l

FIG. 77. SEE NO. 163. COPPER CHLORIDE.

FIG. 78. SEE NO. 156. COBALT CHLORIDE.

FIG. 79. SEE NO. 155. CHROMIUM CHLORIDE.

FIG. 80. SEE NO. 178. POTASSIUM CHROMATE.

MELIOTVPE CO., SOSTOM.

ABSORPTION SPECTRA.

PLATE 21.

.ei .«p M

n|!,:.l5,l:„

M .(^T .1^8 .S^B M .83 .n .SI .M .U .t;8 .47 M M .» .><9 .(p

.u .to .OS

H(i. 81.

FIG. 82.

FIG. 83.

FIG. 84.

FIG. 85.

FIG. 81. SEE NO. 175. NICKEL NITRATE.

FIG. 82. SEE NO. 176. NICKEL SULPHATE.

FIG. 83. SEE NO. 172. LITMUS, BLUE.

FIG. 84. SEE NO. 172. LITMUS, RED.

FIG. 85. SEE NO. 161. COBALT GLASS.

"ELiOTVPE CO., BOSTON

ABSORPTION SPECTRA.

PLATE 22.

3 .62 .ei 60 .SO

FIG. 86.

FIG. 86. SEE NO. 177. PICRIC ACID.

FIG. 87. SEE NO. 148. ACETONE, ETHYL ALCOHOL, ETC.

FIG. 88. SEE NO. 150. ALUMINIUM CHLORIDE, ETC.

FIG. 89. SE^ =:UNDUM AND DIAMOND.

MEHOTyPE CO., eOSTOW.

ABSORPTION SPECTRA.

PLATE 23.

.61 .60 .89 ,68 .67 .66 .SS .Sk ,83 .82 .51 .50 .»» .48 .17 Hi is «« »:1 «J II M ..■11) .08 ,17 .:)« .;<R .HI ,30 .32 .01 .30 .29 .28 ,27 ,2B 26 2» ,20 ,22 ,21 .20

iiliiiiliiiiliiiikiliiiiliiiiiiiiiiiiililiiiiiiuilniiliiiiiiiiiiiiiiiiliiiiliiiiiiiiibii^

FIG. SO.

FIG. 91.

FIG. 92.

FIG. 90. SEE NO. 158. COBALT CHLORIDE IN SOLVENTS.
FIG. 91. SEE NO. 165. COPPER CHLORIDE IN SOLVENTS.
FIG. 92. SEE NO. 164. CHLORIDES OF CALCIUM AND COPPER.

HEDOTrPE CO., BOSTON.

ABSORPTION SPECTRA.

PLATE 24.

.02 ,61 60 ?;■

FIG. 95.

FIG. 93. SEE NO. 165. COPPER CHLORIDE IN ACETONE.
FIG. 94. SEE NO. 158. COBALT CHLORIDE IN ACETONE.
FIG. 95. SEE NO. 157. CHLORIDES OF ALUMINIUM AND COBALT.

HELIOTTPC CO.. BOSTON.

ABSORPTION SPECTRA.

PLATE 25.

S,, «= PY =;.)

FIG. 99.

FIG. 96. SEE NO. 174. NEODYMIUM AMMONIUM NITRATE.

FIG. 97. SEE NO. 174. NEODYMIUM AMMONIUM NITRATE,

FIG. 98. SEE NO. 174. NEODYMIUM AMMONIUM NITRATE.

FIG. 99. SEE PAGE 169.

LIOTYPt CO., BOSTON.

ABSORPTION SPECTRA.

PLATE 26.

.05 .01 .110 -59 ii» .57 ..^0 .55 .S* .63 .52 .51 .50 .19 tS ,17 Yli 15 14 f.l 1J .»1 .»0 .:jl) /M ,n7 JG .115 .3* .;« .fl2 .31 .30 .29 .28 .27 .26 .25 .2* .23 .22 21 .20

py :!ilillinilllllllllllllllllliillllllllllllllllllii;' ' :i'

FIG. 100.

FIG. 100. SEE NO. 180. PRASEODYMIUM AMMONIUM NITRATE.
FIG. 101. SEE NO. 169. ERBIUM CHLORIDE.
FIG. 102. SEE PAGES 5 O^A,<ij 7.0

HELIOTTPE CO., BOSTOM.

ATLAS OF ABSORPTION SPECTRA

BY

H. S. UHLER and R. W. WOOD

WASHINGTON, D. C:

Published by the Carnegie Institution of Washington

May, 1907