Improvements in Apparatus for Standardising and Measuring Intensity of Colour in Transparent Bodies.
Year: 1886

page_text: Date of Application, 9th Oct., 1886. .
Complete Left, 19th Mar., 1887.
Complete Accepted, 26th Apr., 1887.
Improvements in Apparatus for Standardising and Measuring
Intensity of Colour in Transparent Bodies.
JOSEPH WILLIAMS LOVIBOND Twenty Six Saint Ann Street, Salisbury, Brewer,
Maltster, & Wine & Spirit Merchant do hereby declare the nature of this invention to
be as follows
The standard scale is made by evenly tinting glass with the colour to be standardised
so as to be just distinguishable on being looked through towards a white light, and this
I call a single tint or unit of colour, and the place in the scale of any tint is that
represented by the number of units required to produce it. The deeper tints may be
got by making single glasses to represent ten or any other number of units, & working
them singly or in combination.
A separate set of glases must be made & numbered for each colour to be standardised.
The apparatus consists of a tube with two apertures in one end, alterable in size &
shape, and a partition between them so placed that the beams of light entering the tube
through the apertures cannot interfere with each other in passing, the one through the
substance to be tested, and the other through the standardised glasses, all other rays
of light being stopped out. At the other end of the tube is a single aperture & eye
piece commanding a view of the two apertures at the other end, one of which will be
coloured by the liquid or solid to be tested and the other by the standard glasses. To
test a solid for colour place it in the beam of light on one side of the partition and
standard glasses on the other until the colours in the two apertures are equal, the total
of numbers on the glasses used will represent the depth or units of colour in the
substance tested.
When a liquid is to be tested it is placed in a vessel of white glass with parellel
ends at a definite distance from each other; and put into the tube so as to intersect
the beam of light on one side of the partition, standard glasses are then moved into the

page_text: other beam of light until the colours in the two apertures are equal, the total of
numbers on the glasses will represent the depth or units of colour in the liquid tested.
For liquids a thickness of one inch is convenient for comparison with the standard
scale, and is also a suitable thickness for medium tints, but when the liquid to be
tested is much lighter in tint this thickness must be increased in a definite ratio to the
inch or other standard settled upon until it becomes readable. When the liquid is
much darker than the medium tints the thickness must be lessened until it becomes
readable, the thicknesses may be shortened by decreasing the size of the vessel, or
placing blocks of white glass in the vessel the blocks to be of a definite ratio to the
one inch or other standard chosen.
Dated th: 01. 1.
11000
JOSEPH WILLIAMS LOVIBOND.
Intensity of Color in Transparent Bodies.
I JOSEPH WILLIAMS LOVIBOND of 26 St. Ann Street, Salisbury, in the County of
Wilts, Brewer, Maltster and Wine and Spirit Merchant 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 instrument whereby the depth of color of translucent
liquids and solids may be estimated and referred to a prearranged standard scale
progressing in regular degrees.
The instrument is based on the optical comparison of a given sample with a unit or
combination of units of color of known value, the comparison being made by viewing
the sample and the standard unit or units by transmitted light and under precisely
similar optical conditions without liability to error, whether due to the character of the
surroundings or the optical influence on each other of the colors under examination, or
to other cause.
The instrument consists of two juxtaposed tubes which admit the light at one end,
and provided at the other end with a single eye piece commanding a view through
both tubes at once. The tubes are separated by a partition which is so placed that the
beams of light entering the apertures cannot interfere with each other in passing, the
one through the object to be tested and the other through the standard of comparison.
The sample under observation is placed in the one tube and in the other are placed one
or more pieces of evenly tinted glass (or other suitable transparent colored inedium)
each representing a unit of color or any multiple thereof; as many of such standard
tints being used as will, by their aggregate effect when viewed through the eye-piece,
equal in depth of color the color of the sample under observation.
The standard scale of units of color is made by evenly tinting glass, or other medium,
with a color (corresponding to that to be estimated) so as to be just distinguishable

page_text: when viewed by transmitted white light; and this I call a single tint or unit of color,
and the place in the scale of any tint is that represented by the number of units required
to produce it. For deeper tints, standards representing the color value of ten units
or any other multiple of the unit may be used. A separate standard or set of standards
must of course be used for each different color to be estimated. For estimating turbid
liquids, a set of glasses so prepared as to obstruct the light in regular quantities, are
used in combination with clear colored glasses, whereby both the color and the turbidity
of the liquid may be ascertained.
Samples of liquids are contained in transparent vessels having parallel ends at such
distancos apart that the light will be transmitted through a stratum of liquid of known
thickness say, one inch for liquids of medium density of color or fractions or
multiples of that dimension for liquids which are higher or lower in the scale of color.
Instead, however, of employing a series of standard units of color, and varying the
number used, I may employ a fixed standard of color and vary the thickness of the
stratum of liquid under observation by using a series of vessels of progressively varying
dimensions.
Reference is to be had to the accompanying drawings forming part of this
Specification wherein Figure 1 is a side elevation, figure 2 is a plan, figure 3 an end
elevation, figure 4 a horizontal section on line 1-1 figure 1, and figure 5 is a cross
section on line 2-2 figure 2. The same letters of reference indicate the same parts
in all the figures.
The apparatus consists essentially of a pair of juxtaposed tubesc separated by a
partition a the tubes be being open at one end and closed at the other. In the closed
end is an eye-piece d which may be a simple sight hole, or may contain a lens or
lenses, the view through the eye-piece being divided diametrically by the partition a
which is wedge shaped (as shewn in section in figure 4) so as to present a sharp edge
to the eye and render the tubes be slightly divergent, for the purpose of affording a
clear view through both tubes at once with the same eye. By this monocular
arrangement, the error due to any difference which may exist in the color vision of the
two eyes of the observer is avoided.
C
In the top of the one tube c, is an aperture in which is placed a block, of measured
thickness, of the substance to be examined (if solid) or in which is placed a vessel g of
clear glass having its ends g¹ g² parallel and at a known distance apart and containing
the sample of fluid to be examined. The block or vessel (as the case may be) fits in a
corresponding recess in the sides and bottom of the tube c, so as to entirely intersect
the beam of light passing through the tube c. By thus recessing the vessel into the
sides and bottom of the tube, the lateral walls and bottom of the glass vessel are cut
off from the field of view, so as not to affect the accuracy of the observation.
In the top of the other tube b, are a series of slots e at which any number of picces
of tinted glass or other standard (each representing a unit of color, or any multiple
thereof) may be inserted one behind the other, so as to successively intersect the beam
of light transmitted through the tube, until, by their combined or aggregate effect, an
intensity of color is produced equal to that of the sample under examination, the total
color-value of the glasses used representing the depth of color in the said substance.
The pieces of glass & are received in grooves e¹ in the sides and bottoms of the tube b
corresponding to the slots e.
I have shewn the standard tints as being slid into grooves, this being the simplest
arrangement but I would have it understood that I in no way limit myself thereto, but
may adopt any other convenient way of readily causing the standard tints k or any
desired combination thereof to intersect the beam of light in the tube. For instance,
the tints k may be pivoted, so as to swing into and out of operative position, cach tint
moving in its own plane; or, they may be hinged along one of their edges, so as to
fold down within the tube itself and be provided with means of operating them from
the outside of the tube.
The apertures at the open end of the two tubes be are of equal area, and may be
varied in size and shape by means of "stops", and I prefer to modify the light admitted
thereat to prevent undue glare and assimilate observations made under the varying

page_text: conditions of external light, by placing a single piece of ground, opal, or darkened
glass in front of the apertures of both the tubes, as shewn."
As above mentioned, for liquids of medium density, a stratum one inch in horizontal
thickness is suitable, but for much lighter tints this thickness must be increased, and
for much darker tints it must be diminished, in definite ratio to the standard thickness
adopted. The thickness may be reduced either by using a vessel having its walls g'g²
closer together, or by placing blocks of colorless glass in the vessel so as to diminish
the thickness of the colored stratum of liquid traversed by the beams of light, the said
blocks of glass to be equal in thickness to fractions of an inch or other standard of
thickness adopted. In either case, due allowance must be made for the deviation of
the sample from the standard thickness in calculating the color value.
To prevent access of light through such portion of the aperture f as may, for the
time being, be not in use, a sliding cover his applied to the top of the tube. A similar
cover, although not generally necessary, may be applied to the slots e also.
In examining a turbid liquid, a sample, clarified by filtering or other means which
will not affect its color, is first examined for color, as above described, after which it
is replaced by a turbid sample and the colored glasses corresponding to the color of
the filtered sample are supplemented by a similar series of neutral glasses which
obstruct the light, as many of such glasses being used as will make the two fields of
view similar. By this means, both the color and turbidity of the liquid may be
ascertained and referred to a standard scale.
Having now particularly described and ascertained the nature of the said Invention,
and in what manner the same is to be performed; I declare that what I claim is ;-
The herein-described apparatus, for use in estimating the intensity of color of liquids
or solids, consisting of a pair of tubes juxtaposed, open at one end, and provided at the
other with a single eye-piece or aperture commanding a view through both tubes at
once, in combination with a standard tint or a series of such tints intersecting the
beam of light transmitted through the one tube whilst the sample to be tested
intersects the beam of light transmitted through the other tube, as specified.
J. W. LOVIBOND.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.