Improvements in Apparatus for Determining Volumetrically the Amount of Fat in Milk or other Articles.
Year: 1895

page_text: Date of Application, 24th June, 1895
Complete Specification Left, 21st Mar., 1896-Accepted, 6th June, 1896
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Determining Volumetrically the
Amount of Fat in Milk or other Articles.
ALFRED WALTER STOKES F.C.S., F.I.C., of 60 Park Road, Haverstock Hill,
Hampstead, London N.W. Public Analyst and Analytical Chemist do hereby
declare the nature of this invention to be as follows:-
My improvement consists in the use of a glass tube open at both ends, one end
being narrower than the other.
The wider end or mouth can be closed by an india-rubber or other stopper, the
narrow end being furnished at its extremity with a worm or screw made on the
glass, or the screw may be made on a metal or other collar fastened to the glass
tube, so that in either case the opening can be tightly shut by a screw-cap. A
bayonet-joint or other fastening may be used instead of the screw at this end.
The tube is expanded in two places so that it may contain a larger quantity of
the fluids to be used than the rest of the tube.
At the narrow part it is so calibrated that it may show in percentages and in
tenths of a per cent, the fat present in the milk or other article to be tested.
The tube is marked in 3 places so that, without the use of any measuring
vessels, the exact quantities of the requisite materials may be poured by hand
directly into the tube.
The accompanying figure shows in longitudinal section the actual size and shape
of the apparatus that I prefer.
Of course the size & shape may be varied to deal with larger or smaller
quantities of the article the fat of which it is required to determine.
(1) is the india-rubber or other stopper that can be made to fit tightly into the
mouth (2).
(3) is the first bulb or expansion. (4) is the second bulb.
(5) is the narrow calibrated tube which is three inches long and is of such a
capacity that it would contain one cubic centimetre, it is calibrated into 60 parts or
divisions.
(6) is the narrow opening terminating in a screw on to which the metal or other
screw-cap (7) can be tightly fitted by means of an india-rubber pad within the
screw-cap.
The method of using the apparatus is as follows:-
First the screw-cap (7) is fitted tightly on to the screw (6) and the stopper (1)
is left out. Now some amylic alcohol is poured in at the mouth (2) till it
reaches up to the mark (8); this measures 1 cubic centimetres of amylic
alcohol.
Now sulphuric acid of a specific gravity varying from 1820 to 1825 is poured
in till it reaches up to the mark (9); this measures 13½ cubic centimetres of
sulphuric acid.
The milk or other article whose fat is to be determined is then poured in up to
mark (10); this measures 15 cubic centimetres of the milk or other article.
The stopper (1) is tightly fitted into the mouth (2) so that it leaves a space of
one cubic centimetre between it and the milk, and the whole apparatus is-well
shaken for about a minute till the fluids are well mixed. It should now at once be

page_text: rotated in any suitable centrifugal machine giving anything over 800 revolutions
per minute.
If it be so rotated, the calibrated end (6) being placed furthest from the centre
of rotation, it will be found at the end of about minutes that the fat has
separated out in an oily column in the calibrated part of the tube (5). Its per-
centage may readily be ascertained by counting the divisions it occupies; each
division represents one tenth of a per cent. by weight of fat.
The screw-cap (7) may either be taken off or left on during the rotation; the
reading being made with the screw end uppermost.
When the percentage of fat has been read-off the tube may easily be cleaned by
leaving both ends open and then washing it out with hot water.
Having now particularly described & 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 :-
For determining volumetrically the amount of fat in milk or other articles an
apparatus consisting of a glass tube open at both ends but capable of being closed
by a stopper and a screw-cap or other fastening and so doubly dilated near one
end and constricted near the other end and marked that the exact quantities of the
requisite materials may be poured into it without the use of any other measure;
and the constricted part so calibrated that the resulting oily column may be exactly
measured therein.
The construction being such that filling the apparatus, reading off the exact
percentage of fat, emptying the apparatus and cleaning it can readily and speedily
be performed.
Dated this 24th day of June 1895.
Improvements in Apparatus for Determining Volumetrically the
Amount of Fat in Milk or other Articles.
ALFRED WALTER STOKES F.C.S., F.I.C. 60 Park Road Haverstock Hill,
Hampstead, London N.W. Analytical Chemist and Public Analyst, 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 :-
My improvement consists in the use of a glass-tube, open at both ends; one end
being narrower than the other. The wider end (or mouth) can be closed by an
india-rubber or other stopper; the narrow end being furnished at its extremity
with a worm or screw made on the glass; or the screw may be made on a metal or
other collar fastened to the glass-tube, so that in either case the opening can be
tightly shut by a screw-cap. A bayonet-joint or other fastening may be used
instead of the screw at this end.
The tube is expanded in two places so that it may contain there a larger quantity
of the fluids to be used than the rest of the tube.
At the narrow part it is so calibrated that it may show in percentages and in
tenths of a per cent. the fat present in the milk or other article to be tested.
The tube is marked in 3 places, so that without the use of any other measuring
vessels the exact quantities of the requisite materials may be poured by hand
directly into the tube.
The figure left with the Provisional Specification shows in longitudinal section
the form and shape of the apparatus.

page_text: Of course the size and shape may be varied to deal with larger or smaller
quantities of the article the fat of which it is required to determine.
(1) is the india-rubber or other stopper that can be made to fit tightly into the
mouth (2).
(3) is the first bulb or expansion.
(4) is the second bulb.
(5) is the narrow calibrated tube which is about 3 inches long and is of such a
capacity that it would contain one cubic centimetre, it is calibrated into 60 parts or
divisions.
(6) is the narrow opening terminating in a screw, on to which the metal or
other screw-cap (7) can be tightly fitted by means of an india rubber-pad within
the screw-cap.
The method of using the apparatus is as follows:-First, the screw-cap (7) is.
fitted tightly on to the screw (6). Now, some amylic alcohol is poured in at the
mouth (2) till it reaches in the tube up to mark (8); this measures 1 cubic-
centimetres of amylic alcohol.
Now, sulphuric acid of a specific gravity varying from 1820 to 1830 is poured
into the tube up to the mark (9); this measures 13 cubic centimetres of sulphuric
acid. The milk or other article whose fat is to be determined is then poured into
the tube up to the mark (10); this measures 15 cubic centimetres of the milk or
other article. The stopper (1) is tightly fitted into the mouth (2) so that it leaves
a space of about 1 cubic centimetre between it and the milk or other article, and
the whole apparatus is well shaken for about a minute till the fluids are well
mixed.
It should now at once be rotated in any suitable centrifugal machine giving
anything over 500 revolutions per minute.
If it be so rotated, the calibrated end (6) being placed furthest from the centre
of rotation, it will be found at the end of about 5 minutes that the fat has separated
out as an oily column in the calibrated part of the tube (5). Its percentage may
readily be ascertained by counting the divisions of the tube that it occupies. Each
division represents one tenth of a per cent. by weight of fat. The screw cap (7).
may either be taken off or be left on during the rotation, the reading of the
percentage of fat being made with the screw-end uppermost.
In default of a centrifugal apparatus the tube should be immersed with its
contents after mixing in some water kept at a temperature of 150° to 180° F. the
screw-end being vertically uppermost.
If kept at this temperature for at least an hour the fat will rise into the
calibrated part of the tube and its percentage may be there read off.
In either case, after ascertaining the percentage of fat, the tube may easily be
cleaned out by leaving both ends open and then washing it out with hot water.
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 :-
For determining volumetrically the amount of fat in milk or other articles (such.
as cream, cheese, emulsions and the like) an apparatus consisting of a glass-tube
open at both ends but capable of being closed by a stopper and a screw-cap or
other fastening and so doubly dilated near one end and constricted near the other
end and so marked that the exact quantities of the requisite materials may be
poured into it without the use of any other measure.
The construction being such that filling the apparatus, reading off the exact
percentage of fat, emptying the apparatus and cleaning it can be readily and.
speedily performed.
Dated this 20th dor of Marsh 1806