Improvements in and Apparatus for Ascertaining the Percentage of Fat in Milk and other like Liquids.
Year: 1893

page_text: Date of Application; 4th Feb., 1893
Complete Specification Left, 6th Nov., 1893-Accepted, 9th Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in and Apparatus for Ascertaining the Percentage of
Fat in Milk and other like Liquids.
I AUGUST NICOLAUS NAHM of No. 38 Steindamm Königsberg in the Kingdom
of Prussia, German Empire, Chemist and Engineer do hereby declare the nature
of this invention to be as follows:-
This invention relates to an improved means for ascertaining the percentage of
fat in milk and other like liquids.
The process according to this invention consists in mixing the milk or other
liquid, preferably heated with another liquid (which I will call the decomposing
liquid) consisting of amyl alcohol and a solution of a caustic alkali (such as caustic
soda, potash or ammonia) in strong ethyl alcohol. The mixture is digested in a
closed vessel heated to the boiling point of water and is frequently shaken or
agitated and afterwards it is allowed to stand when the solution of fat forined
collects in a separate layer upon the surface of the liquid. Without disturbing the
relative positions the matters are passed into a measuring vessel (provided with a
graduated scale) until the line of demarcation between the solution of fat and the
other part of the liquid coincides with the zero point on the scale which is so
regulated that it indicates the percentage of fat in the original liquid.
A suitable decomposing liquid consists of 1500 parts by measure of a 6 per cent.
alcoholic potash lye prepared with ethyl-alcohol of 96 per cent. strength 400 parts
by measure of amyl alcohol and 600 parts by measure of ammonia liquor of
from 20 to 25 per cent. strength.
25 parts by measure of this liquid are employed to 100 parts by measure of the
liquid to be tested; milk for example.
In place of the ethyl-alcohol, methyl-alcohol and the other known water soluble
solvents of amyl-alcohol may be employed.
The apparatus for carrying out the process may consist of a vessel employed for
the decomposition and connected with a graduated measuring tube. The vessel is
entirely or partly constructed with flexible or yielding walls. For example the
lower part may be formed by a ball or sphere of rubber. A rubber tube is
connected to the open extremity of the measuring tube.
This rubber tube is provided with a spring clamp by which it can be closed or
the measuring tube may have a cock or valve arranged below the rubber tube.
Whilst the digesting is going on the said tube is closed, after cooling the said
tube is opened and air exhausted through the tube, a partial vacuum being
produced in the vessel so that the external atmospheric pressure forces the yielding
part of the vessel gradually inwards or together so that the contents of the vessel
are forced into the measuring tube without mixing them together. The exhaust or
suction is continued until the line of demarcation between the milk and the solution
of fat coincides with the zero point on the scale and the tube is then closed. The
percentage of fat in the liquid being tested can then be ascertained by reference to
he scale.
In combination with this arrangement a water bath may be employed which
enables a number of measuring apparatus to be heated simultaneously.
The water bath vessel has an inwardly bent edge or rim with circular recesses
and in front of each recess there is a perpendicular rod attached to the vessel and
forming a fork at its upper end in which the decomposing apparatus or receptacle
with the measuring tube is suspended, a small ring arranged upon the latter
engaging with the fork. This ring should be capable of movement upon the

page_text: measuring tube so as to enable the apparatus to be immersed: more or less into the
water. When the measuring apparatus are placed in position the water bath is
closed by a lid or cover likewise provided with recesses.
The water bath is attached to rods or supports upon which it can be adjusted
vertically. The rods are attached to a base plate on which is placed a burner or
lamp serving to heat the water bath.
Dated the 4th day of February 1893
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
: COMPLETE SPECIFICATION.
Improvements in and Apparatus for Ascertaining the Percentage of
Fat in Milk and other like Liquids.
I, AUGUST NICOLAUS NAHM of Königsberg in the Kingdom of Prussia, Doctor
of Philosophy, Chemist and Engineer 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 improved means that is to say an improved method
and apparatus for ascertaining the percentage of fat in milk and other like
liquids.
66
The method according to this invention consists in mixing the milk or other
liquid preferably heated with a liquid, hereinafter called the decomposing
liquid," consisting of a mixture of amyl alcohol and a solution of a caustic alkali
(such as caustic soda, potash or ammonia) in strong ethyl alcohol. The mixture
of milk and decomposing liquid is digested for about hour, in a closed vessel
heated to the boiling point of water. In order to promote the dissolving of the
fat by the decomposing liquid the apparatus should be frequently shaken during
this operation. After digesting, the mixture is allowed to cool when the solution
of fat formed, collects in a separate layer upon the surface of the liquid. Without
disturbing their relative positions the two bodies are caused to pass by the
co-operation of the atmospheric pressure and of a partial vacuum created in the
decomposing vessel into a vessel or chamber communicating with the decomposing
vessel and provided with a graduated scale, until the line of demarcation between
the solution of fat and the liquid coincides with the zero point on the scale. The
latter is so arranged as to indicate under these conditions the percentage of fat
contained in the liquid under examination.
A suitable decomposing liquid consists of 15 parts by volume (1500 cubic
centimetres) of a 63 per cent. alcoholic potash lye prepared with ethyl alcohol of
96 per cent. strength 4 parts (400 cubic centimetres) of amyl alcohol and 6 parts
(600 cubic centimetres) of ammonia liquor of from 20 to 25 per cent. strength.
0.25 parts (25 cubic centimetres) of this liquid are employed to 1 part
(100 cubic centimetres) of a liquid to be tested such as milk for example.
In place of the ethyl alcohol, methyl alcohol and the other known water-soluble
solvents of amyl alcohol may be employed.
The apparatus for carrying out the improved method of testing consists of a
decomposing vessel and a graduated measuring vessel communicating with the
former and combined with means for closing it from the atmosphere, and with a
suction tube, the decomposing vessel being entirely or partly constructed with
flexible or yielding walls.
On the annexed sheet of drawings the said apparatus is represented in a form
which I have found to give good results in practice.
Figure 1 shows the apparatus in elevation with the partly yielding or flexible
decomposing vessel in its normal condition, whilst Figure 2 is an elevation of the
apparatus with the yielding bottom part of the said vessel forced inwards in

page_text: the act of passing the contents of the decomposing vessel into the measuring
vessel.
a is the decomposing vessel. The upper part of same is preferably made of
glass, whilst the lower part is formed by a ball or sphere of rubber 6 hermetically
connected with the glass part. This rubber part 6 may be protected by an
enclosing net c. The upper part of the vessel a is extended in the form of a
tube d forming a measuring vessel and this tube is provided with a scale e arranged
as hereinbefore described. Instead of extending the upper part of the vessel a in
the form of a tube a separate glass tube may be employed being connected with an
orifice in the top of the vessel a or the latter may be provided with a tubular
arrangement to which the measuring tube is connected by means of a short rubber
tube for example. To the open upper extremity of the measuring tube d is fixed
a rubber tube 9, and this is provided with a spring clamp for closing and opening
it, or in place of this arrangement the measuring tube itself may have a cock or
valve at a suitable point below its open upper extremity as shewn in dotted lines in
Figure 1 for example.
The rubber tube may be provided with a mouthpiece h. For the purpose of
reducing the length of the measuring tube the same may be made with a widened
part d' as shewn in dotted lines in Figure 1.
In carrying out a test the milk and decomposing liquid prepared as hereinbefore
described are mixed in the proportions given and the mixture is introduced into
the vessel a through the measuring tube d the rubber tube g being removed. The
rubber tubeg is then attached to the measuring tube e and the apparatus is hermetically
closed by means of the spring clamp for its equivalent after which the apparatus is
heated preferably by means of a water bath, and its contents allowed to digest for
about hour at the boiling point of water the apparatus being frequently shaken in
order to promote the dissolution of the fat by the decomposing liquid.
During the digesting process the lower part 6 by virtue of its flexibility expands
and contracts according to the changes of the pressure within the vessel so that the
latter is prevented from bursting. The apparatus is then allowed to cool until the
solution of fat formed by the preceding operation has collected in a separate layer
on the surface of the liquid.
The spring clamp or its equivalent is then opened and a partial vacuum is
produced in the apparatus by gently sucking or exhausting the air through the
tube g whereby the external atmospheric pressure is caused to force the yielding
lower part of the vessel a gradually inwards or together causing its sides to
collapse as shewn in Figure 2 and the contents of the vessel a are caused to rise
into the measuring tube d without mixing them together. The suction or exhaust-
ing action is continued until the line of demarcation between the solution of fat and
the remaining liquid coincides with the zero point of the scale e when the spring
clamp or its equivalent is again closed and the percentage of fat read off on the
scale e.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is―
1. The method of ascertaining the percentage of fat in milk and other liquids
consisting in mixing the liquid to be tested with a decomposing liquid composed of
amyl alcohol and an alcoholic solution of a caustic alkali or caustic alkalis, heating
the mixture in a closed vessel at the boiling point of water, allowing the mixture to
cool and passing as described the solution of fat collected on the surface of the
liquid, into a measuring vessel until the line of demarcation between the fat solution
and the liquid coincides with the zero point of the scale of the measuring vessel
substantially as hereinbefore set forth.
2. An apparatus for testing liquids in accordance with the method referred to
in the preceding claiming clause consisting in the combination with a vessel for
containing the mixture of liquids and entirely or partly constructed with flexible

page_text: or yielding walls of a measuring tube communicating with the said vessel, means
for hermetically closing the measuring tube and a suction or exhausting tube
connected with the measuring tube substantially as and for the purpose hereinbefore
described with reference to the accompanying drawings.
Dated this 6th day of November 1893.
J. H. JOHNSON & Co.,
Agents.