Improvements in Apparatus for Testing the Acidity of Milk and other Liquids.
Year: 1897

page_text: Improvements in Apparatus for Testing the Acidity of Milk
and other Liquids.
We, ALFRED WALTER STOKES, F.C.S., F.I.C., of 60, Park Hill Road, Haver-
stock Hill, Hampstead, London, Public Analyst and Analytical Chemist,, and
R. A. LISTER & CO. LIMITED, of Victoria Iron Works, Dursley, Gloucester-
shire, Engineers and Ironfounders, do hereby declare the nature of this inven-
tion to be as follows:-
:-
This invention consists in improvements in apparatus for testing the acidity
of milk and other liquids whereby are obtained the advantages of greater exacti-
tude in the ascertainment and indication of the acidity, a greater simplicity in
working and a greater cheapness in first cost as compared with apparatus as
heretofore constructed; this apparatus from its great portability and readiness
for use is moreover suitable for all situations and notably for large and small
farms.
The apparatus consists only of a drop bottle and a measuring tube both of new
or improved construction and of an ordinary stirring rod.
The measuring tube is of glass and is provided with a graduated index with
numerals from 0 to say 6. The graduation lines are partly on a clear glass
part and partly on a white opaque part or stripe. The drop bottle is fitted with
a glass stopper provided with a drop tube spout branch and a longer and larger
air inlet tube branch over this is placed a removable bell or cap which is ground
air tight on the top of the bottle.
To use the apparatus for testing say the acidity of milk the measuring tube is
filled with the milk up to the zero mark and the stirring rod is then placed in it.
The drop bottle containing the solution, a suitable mixture of caustic soda and
phenol phthalein or other indicator is then taken in the hand and the solution
poured into the milk in the measuring tube dropwise and more rapidly at first
while stirring with the rod. When the milk assumes a permanently pale pink
colour (in the case of phenol phthalein) that is to say when the limit of the
neutralization has been reached and just passed no more solution is to be poured
in whereupon the glass rod is removed and the liquid level observed in the
measuring tube as indicated by the graduation this indicates the acidity of the
milk sample in tenths and hundredths of a per cent. of lactic acid.
To ascertain the acidity of curdled milk a larger measuring tube is used or
preferably an equal bulk of water is added to the milk and then the operation is
proceeded with as above; in this latter case the figures obtained must be doubled.
To prevent spilling of the liquid while the drop bottle is carried about from
place to place in daily use an ordinary glass stopper may be temporarily put in
instead of the special form of stopper described which latter however is used on
the spot as required.

page_text: By means of this construction of apparatus the possibility of accidental or care-
less dilution and deterioration of the liquid in the supply bottle are prevented.
Dated this 25th day of September 1897.
JENSEN & SON,
0
77, Chancery Lane, London, W.C., Patent Agents.
Improvements in Apparatus for Testing the Acidity of Milk
and other Liquids...
We, ALFRED WALTER STOKES, F.C.S., F.I.C., of 60, Parkhill Road, Haver-
stock Hill, Hampstead, London, Public Analyst and Analytical Chemist, and
R. A. LISTER & COMPANY LIMITED, of Victoria Iron Works, Dursley, Gloucester-
shire, Engineers and Ironfounders, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed to be particularly, described
and ascertained in and by the following statement:-
This invention consists in improvements in apparatus for testing the acidity
of milk and other liquids whereby are obtained the advantages of greater exacti-
tude in the ascertainment and indication of the acidity, a greater simplicity in
working, and a greater cheapness in first cost as compared with apparatus as
heretofore constructed; this apparatus from its great portability, and readiness
for use is moreover suitable for all situations and notably for large and small
farms.
The apparatus consists only of a drop bottle and a measuring tube both of new
or improved construction and of an ordinary stirring rod.
The measuring tube is of glass and is provided with a graduated index with
numerals from 0 to say 6. "The graduation lines are partly on a clear glass
and partly on a white opaque part or stripe. The drop bottle is fitted with a glass
stopper provided with a drop tube branch and a longer and larger air inlet tube
branch over this is placed a removable bell or cap which is ground air tight on
the top of the bottle.
Referring to the drawing Fig. 1 is a sectional elevation of the drop bottle and
Fig. 2 is an elevation of the measuring tube.
Referring to Fig. 1 the drop bottle A is fitted with a stopper B which is ground
into the neck A¹ of the bottle and is provided with a drop tube branch B¹ and
an air inlet tube branch B2. The drop bottle A is formed with a shoulder A² to
receive a removable bell or cap C which covers the neck A' and the stopper B
with the branches B1 and B2. The shoulder A² and cap C are ground so as to
make an air tight joint.
Referring to Fig. 2 the measuring tube D of glass is provided preferably with
a spout or lip D₁ and with a graduated index with numerals from 0 to say 'G.
For testing milk it is sufficient if the index reaches 4 as shown on the drawing.
The graduation lines are partly on a clear glass part and partly on a white
opaque part or stripe indicated on the drawing by dotted lines marked E, E
and E¹, E..
To use the apparatus for testing say the acidity of milk the measuring tube D
is filled with milk up to the zero mark and a stirring rod is then place in it.
The drop bottle A containing the solution, for instance, a suitable mixture of
caustic soda and phenol-phthalein or other indicator is then taken in the hand
and the solution poured into the measuring tube D dropwise preferably more
rapidly at first while stirring with the rod. When the milk assumes a per-
manently pale pink colour (in the case of phenol-phthalein) that is to say when

page_text: the limit of neutralization has been reached and just passed, no more solution is
to be dropped in, whereupon the glass rod is removed and the liquid level observed
in the measuring tube D'as indicated by the graduated index.
This indicates the acidity of the milk sample in tenths and hundredths of a
per cent. of lactic acid. For example in the drawing the liquid is indicated at F
as standing in the tube D at '15 the sample of milk in such a case contains there-
fore 1 tenth and 5 hundredths of a per cent of lactic acid or %
15
100
To ascertain the acidity of curdled milk a larger measuring tube is used or
preferably an equal bulk of water is added to the milk and then the operation is
proceeded with as above described; in this latter case the figures obtained must
be doubled.
•
To prevent spilling of the liquid while the drop bottle A is carried about from
place to place in daily use an ordinary glass stopper may be temporarily put
instead of the special form of stopper B already described which latter however is
used on the spot as required.
By means of this construction of apparatus the possibility of accidental or care-
less dilution and deterioration of the liquid in the supply bottle are prevented.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:-
1. The construction of drop bottle stopper described and shown.
2. The construction of measuring tube described and shown.
Dated this Twenty-seventh day of June 1898.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.