AN APPLIANCE FOR TESTING THE QUALITY OF MILK
Year: 1884

page_text: I FRANCIS THOMAS BOND, of Gloucester, in the county of Gloucester, Doctor
of Medicine, do hereby declare the nature of any invention for AN APPLIANCE
FOR TESTING THE QUALITY OF MILK to be as follows:-
The application in which my invention consists is founded upon the well known
fact that the opacity of milk is very largely dependent upon and proportionate to
the amount of butter fat which it contains. By comparing the relative opacities,
or the powers of transmitting light, of laminæ of the same thickness of milk from
different sources, the richness of such samples of milk in butter fat can be estimated
either relatively to one another or to a common standard.
For the purposes of this invention I take a tray or saucer of white porcelain,
metal, or other suitable white material, and on the floor thereof I trace some optical
design, such as a series of parallel black lines; or words; or a geometric or other
pattern; or in fact any design which can be distinctly and readily recognised by
the eye.
The more readily such a pattern can be so recognised the better it is for
the purpose; and I find that a series of parallel black lines on a white ground are
well adapted for the purpose, because their recognition is made more appreciable
by the fact that they can be counted.
In order to use the appliance so constructed I place the tray or saucer on a table
in front of a window, and, standing immediately over it, I introduce into it a given
quantity of clear water; and I then cause the milk which is to be tested to flow
into the water by drops or in any other graduated way, stirring the mixture
meanwhile, until the eye ceases to be able to count the number of lines, or to
recognise the other pattern which may be delincated on the floor of the tray or
saucer.
By comparing various samples of milk in this way it will be found that the
number of drops or other graduated quantities of milk which are required to be
introduced into the water in each case have a relation to the richness of the
samples in butter fat, the smaller the number of drops or other graduated quantities
required to produce opacity the richer the sample.
In making the test care must be taken to use a uniform appliance for measuring
the drops or other graduated quantities of milk, so that the results may be com-
parable; also that the tray or saucer is of uniform shape and size, and that the

page_text: amount of water introduced into it is in all cases the same, so that the depth of the
stratum of water at starting may be always the same.
By determining the number of drops or other graduated quantities of milk of a
given richness in butter fat, say 5 per cent, which are necessary to produce
obscuration of the design, an absolute standard may be formed with which any
sample of milk may be compared, and by which its absolute percentage of fat may
be estimated; and from such a standard a table of percentages of fat corresponding
to various numbers of drops or other graduated quantities of milk may be readily
deduced.

page_text: I FRANCIS THOMAS BOND of Gloucester in the County of Gloucester Doctor of
Medicine do hereby declare the nature of my Invention for AN APPLIANCE FOR
TESTING THE QUALITY OF MILK and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :―
The application in which my invention consists is founded upon the well known
fact that the opacity of milk is very largely dependent upon and proportionate to
the amount of butter fat which it contains. By comparing the relative opacities
or the powers of transmitting light of laminæ of the same thickness of milk from
different sources the richness of such samples of milk in butter fat can be estimated
either relatively to one another or to a common standard. For the purposes of
this invention take a tray or saucer of white porcelain, metal or other suitable
white material and on the floor thereof I trace some optical design, such as a series
of parallel black lines, or words, or a geometric or other pattern; or in fact any
design which can be distinctly and readily recognised by the eye.
The more readily such pattern can be recognised the better it is for the purpose.
I find that a series of parallel black lines is well adapted for the purpose because
their recognition is made more appreciable by the fact that they can be counted.
In order to use the appliance so constructed I place the tray or saucer on a table
in front of a window, and, standing immediately over it, introduce into it a
measured quantity of clear water and I then cause the milk which is to be tested
to flow into the water by drops, or in any other graduated way, stirring the
mixture meanwhile until the eye ceases to be able to count distinctly the number
of lines, or to recognise any other pattern which may be delineated on the floor of
the saucer or tray. By comparing various samples of milk in this way it will be
found that the number of drops or other graduated quantities of milk which are
required to be introduced into the water in each case have a relation to the richness
of the samples in butter fat; the smaller the number of drops or other graduated
quantities required to produce opacity the richer the sample in butter fat. In
making the test for comparative purposes care must be taken to use a uniform
appliance for measuring the drops or other graduated quantities of milk, so that
the results may be comparable; also that the tray or saucer is of uniform shape
and size, and the amount of water introduced into it is in all cases the same, so
that the depth of the stratum of water may, on commencing to drop the milk, be
always the same.
By determining the number of drops or other graduated quantities of milk of a
given richness in butter fat, say 5 per cent, which are necessary to produce
obscuration of the design, an absolute standard may be formed, with which any
sample of milk may be compared, and by which its absolute percentage of fat may
be estimated; and from such a standard table percentage of fat corresponding to
various numbers of drops or other graduated quantities of milk may be readily
deduced.
Instead of delineating the lines or other pattern adopted on the floor of a saucer
of porcelain or other opaque material they may be also delineated on the under
surface of a saucer of glass or other transparent material, either by engraving them
thereon, or by engraving them on paper and attaching the paper thus engraved,
with its engraved pattern uppermost, to the under surface of the saucer, so that
the pattern shall thus be visible through the flor of the saucer.

page_text: I find it convenient to provide with the saucer a small measure for regulating
the amount of water to be used, which may be one ounce or any other definite
quantity; and also a pipette or dropping tube, with a nozzle of uniform size,
which may be made to give drops weighing one grain each of standard milk. But
other measure may be adopted if preferred.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed. I declare that what
I claim is, a saucer or other similar vessel, with an appropriate pattern delineated
on the upper or under surface of the bottom thereof (according to whether the
material of which the saucer is made is opaque or transparent), the same being
provided with an arrangement for supplying a uniforin quantity of water to the
saucer, and also with an appliance for adding milk to the water in the saucer in
such a way that the obsuration of the pattern when produced can be estimated
according to the number of drops used, and the result thus obtained used by
comparison with data previously provided, by chemical analysis or in any other
way to discover the percentage of butter fat which the milk contains; the whole
three appliances thus forming one apparatus for carrying out the purposes of my
invention.