An Improved Colourimeter, more especially applicable for use as an Ozonometer.
Year: 1898

page_text: Date of Application, 13th Aug., 1898-Accepted, 24th Sept., 1898
COMPLETE SPECIFICATION.
An Improved Colourimeter, more especially applicable for use as an
Ozonometer.
I, MARIUS OTTO, of 18, Avenue de Neuilly, Neuilly-sur-Seine, in the Republic
of France, Doctor of Science, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be, particularly described and
ascertained in and by the following statement:-
This invention relates to an apparatus, the object of which is to enable two
colourations of the same nature of liquids or gases to be compared.
The apparatus is especially applicable for the instantaneous proportioning of
ozone, that is to say for finding at any time by a simple reading operation, the
proportional quantity of ozone contained in a gaseous mixture.
The essential feature of this improved colourimeter is to bring into the scope of
view of one and the same eye glass, two tints which are to be compared and
which respectively occupy, one the upper part and the other the lower part of
one and the same circle. The operation of the apparatus consists in equalizing
these two tints.
In the case of gases and of ozone in particular, I attain this result by the aid
of an operating handle; in the case of liquids, simply the respective heights of
the columns of the standard liquid and of the liquid to be examined, are com-
pared the said liquids having for this purpose to be interposed in a pencil of rays
emanating from one and the same source of light, in order to obtain identical
tints within the two semi-circles.
By way of example I will describe a case where my colourimeter acts as an
instantaneous ozonometer.
Ozone, seen in a certain thickness, is blue: if all conditions are equal, the
intensity of the colouration or tint indicates the proportional quantity of ozone
or of the gaseous mixture to be examined. This is of course only the case when
the gaseous mixture which serves as a vehicle or medium for conveying the ozone,
is itself colourless.
Supposing we have established a scale of tints, indicating; to what proportional
quantity of ozone would correspond a given intensity of colouration in the case
of a tube or a series of tubes of one and the same length being employed which
are subjected to the temperature t and to the pressure H. In order to determine the
proportional amount of ozone of a gas contained in a tube or a series of tubes of
one and the same length 1, subjected to the temperature t and to the pressure H,
it will be sufficient that the colouration observed in this tube or tubes be made
to correspond to one of the colourations, provided on the scale of tints, by the aid
of an appropriate device; by a simple reading operation we shall then be able to
derive or ascertain the proportional amount of ozone in the gas to be examined.
Such is the principle, on which the apparatus, forming the subject of my invention,
is operated.
My improved apparatus is illustrated in the accompanying drawings in which:
Figure 1 is a vertical section of the improved apparatus.

page_text: -
igures 1 and 13 show a detail view of the prisms.
Figure 2 is a side elevation of the improved apparatus, and
Figure 3 shows diagrams hereinafter referred to.
1
My ozonometer consists of a three-armed tube T¹ T2, #2, T, T₁₂, each tube
being divided in two parts by intermediate partitions M¹ m¹ M². These tubes are
represented in section in the accompanying drawing (Figure 1).
In one half of each tube TT, circulates the ozonized gas to be analyzed; for
instance ozonized air; the other half is filled with air only. The tubes are closed
by glass plates X X¹.
The ozonized air passes into the tube T through the tubular connection E,
shown in side elevation in Figure 2, but it leaves through the tubular connection S,
fixed to the tube T¹. A thermometer a fastened on the face of the apparatus and
a pressure gauge M branching off from the admission conduit for the ozonized
air indicate the temperature and the pressure of the analyzed gas.
A system of two prisms P1 P2, shown in section in Figure 1, in elevation in
Figure 1 and in plan in Figure 1º, of blue-coloured glass, with externally parallel
faces, and capable of sliding upon one another, constitutes the scale of tints, these
said prisms forming in reality a blade of variable thickness. They are operated
by the aid of a screw-threaded rod or spindle F the threads of which are right and
left handed and controlled by the operating knob V2 (Figure 2). The luminous
rays emitted from a source of light S* (Figure 1) arranged at the entrance of
the arm TT below the glass plate X, traverse, on the one hand, the ozonized
atmosphere, contained in the compartments T, T, and on the other hand the layer
of air, contained in the compartments T, T. The prism with total reflection P,
which caps the horizontal arm of the tubes and the mirror N arranged at the lower
part, where the branches T, T₁₂ terminate below the glass plate X1, send the two
images formed by the source of light into the field of view of an eye piece L,
which can be focussed by the knob V. The arrows indicate the passage of the
pencil of luminous rays. It is to be seen from the section (Figure 1) that the
system of prisms P1 P2 lies within the pencil of rays which has traversed
the compartments T2 T₁₂ containing the pure air.
2
2
The prism P1 carries a vernier (Figure 2) which is adapted to move opposite
a scale e, which is provided with graduations indicating the milligrammes of
ozone per litre of air, at zero temperature and at a pressure of 760 millimetres, and
the proportional quantity of ozone contained in the gaseous mixture undergoing
analysis. A table connected to the apparatus permits of easily correcting for
pressure and temperature.
Figure 3 indicates what is seen in the field or scope of view of the eye piece.
(Image 1) If there is no ozone present in the apparatus, the lower semi-circle
only is slightly blue-coloured owing to the interposition of the bi-prism in a
portion of the pencil of rays.
1
2
(Image II) When the ozonized air enters the tubes T₁ T₁ the upper part of
the semi-circle assumes a blue tint, which differs from that of the lower part.
(Image III) By operating the knob V, the thickness of that portion of the
bi-prism which imparts its colouration to the lower part is varied. When the 4
two tints are equal, it is only necessary to read from the graduated scale-by
the aid of the vernier carried by the prism P-the result of the experiment.
The bi-prism may be replaced by other devices for instance by glass plates of
different tints or variable thickness, by layers of coloured liquids of a variable
thickness and so forth.
In case where my colourimeter is to be utilized for comparing the intensity of
colourations of two liquid layers, nothing is more easy than to effect this com-
parison.
5
The two prisms are so moved away from each other as to enable the pencil of
rays which strikes them, to freely pass; in one of the compartments of the double 5
tubes the standard liquid is introduced and in the other the liquid to be examined;
the height of the latter is varied, until the colourations observed in the eye piece

page_text: are identical. The length of the columns which are interposed in the passage of
the luminous rays are then read off.
The pressure gauge M presents a novel arrangement which is of a certain
interest. The same is provided with a movable scale R capable of sliding on
two small rollers r, fixed upon the face plate K of the pressure gauge. These
two small rollers are shown in dotted lines in the drawing Figure 2. To the
zero point of the scale corresponds an index finger 62. On pressing a small button bo
the index finger may be passed up to the mercury level upon one of the arms;
another index finger 63 which is adapted to slide upon a small rigid body y,
indicates the level of mercury in the other branch or arm of the pressure gauge
and the difference in the heights can be read with great facility.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be. performed, I declare that what I
claim is:-
The colourimetric apparatus, above described and represented in the accom-
panying drawing; the essential features of which are:-
(a). A system of coloured prisms adapted to slide upon one another and forming
a blade having parallel faces of a variable thickness, one of the prisms carrying
a vernier, adapted to move opposite a graduated scale;
(b). A series of parallel tubes in two compartments traversed by pencils of
luminous rays emanating from one and the same source of light in such a
manner that the path traversed is the same for both gases or liquids to be
compared;
(c). An eye piece or lens, in the field of which the images furnished by the
apparatus, are observed;
(d). A pressure gauge with movable scale.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.