Improvements in the Means of Determining Acidity or Alkalinity in Milk or other substances.
Year: 1890

page_text: Date of Application, 3rd June, 1890
Complete Specification Left, 13th Nov., 1890-Accepted. 10th Jan., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Means of Determining Acidity or Alkalinity
in Milk or other substances.
I, ALFRED WALTER STOKES 30 Haverstock Hill, Hampstead, London N.W., Public
Analyst and Analytical Chemist, do hereby declare the nature of this invention to be
as follows:-
:-
My improvements consist in the use of pellets or pillules for the purpose of
determining the acidity or alkalinity of milk or other substances. These pellets con-
tain their own coloring matter or "indicator" which may be litmus, turmeric,
cochineal, phenol-phthalein, lacmoid, phenacetolin, methyl orange or other coloring
matter.
For determination of acidity the pellets also contain any of the alkaline materials
such as the carbonates, bicarbonates or hydrates of soda or potash, or the hydrates
of baryta or lime.
For determination of alkalinity the pellets contain besides coloring matter any of
the acids such as oxalic, tartaric, citric or other acids or their acid salts.
The pellets are made to contain such a proportion of alkali or acid as when dropped
into a suitable volume of milk or other liquid will at once show by the production or
alteration of a color the percentage of acidity or alkalinity present in the milk or other
substance.
Thus, in the case of milk I prefer to use pellets containing 0.212 grain of dry
carbonate of soda moistened with a saturated alcoholic solution of phenol-phthalein.
These ingredients may be mixed with any inert matter such as starch, milk-sugar, &c.
to give bulk and to ensure easier solution and are so lightly compressed that they at
once break up and dissolve on shaking with the milk. Ten cubic centimetres of the
milk to be tested are placed in a tube marked at that volume and the pellets are
dropped in one by one and the tube shaken on each addition till the milk turns a
decided pink color. The number of pellets required to produce this color shows at
once the acidity in tenths of a per cent. of lactic acid of the sample of milk.
For instance, if 10 c. c. of milk required 7 pellets to give it a pink color that sample
would contain 7 tenths of a per cent. of lactic acid.
The advantages of the use of these pellets are:-
No burettes, pipettes, standard-solutions or special apparatus are required. No
calculation of results is needed, nor any special skill involved.
Only a test-tube and a supply of pellets are required by this method which may be
used by the most unskilled & ignorant.
Dated this Camandliv # Tune 1900
COMPLETE SPECIFICATION.
Improvements in the Means of Determining Acidity or Alkalinity
in Milk or other substances.
ALFRED WALTER STOKES 30 Haverstock Hill, Hampstead, London, N.W.,
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 improvements consist in the use of pellets or pilules for the purpose of
determining the acidity or alkalinity of milk or other articles. These pellets contain
their own coloring-matter or "indicator" which may be phenol-phthalein, litmus,

page_text: methyl-orange, lacmoid, phenacetolin, tarmer'c, cochineal or other suitable coloring-
matter. They also contain any of the alkaline materials such as the carbonates or
bicarbonates of soda or potash, or any of the hydrates of barium, strontium, calcium,
soda or potash for determining acidity; or oxalic, citric, tartaric or other acid or any
of the acid-salts of these may be used for determining alkalinity. These pellets are
made each to contain such an accurate proportion of any of these ingredients as when
dropped into and dissolved by a suitable quantity of the liquid to be tested they shall
at once show the percentage of acility or alkalinity of the liquid.
Thus, in the case of milk, I prefer to use pellets containing each 0212 grain of dry
carbon.ite of soila, moistened with a saturated alcoholic solution of phenol-phthalein.
These ingredients may be mixed with any inert matter such as starch, milk-sugar, &c.
and should be so lightly compressed that they at once break up and dissolve when
shaken with the milk or when crushed in it by a stirring-rod. Ten cubic centimetres
of the milk are placed in a test-tube or like appliance. the pellets are dropped in and
made to dissolve one by one till the milk turns a decided pink color. The number of
pellets required to give a permanent pink color shows at once the acidity in tenths
of a per cent. of lactic acid of the sample of milk taken.
The advantages of the use of these pellets for determining acidity or alkalinity are
that no burette, pipette, standar.l-solution or special apparatus is needed.
No
calculation of results is entailed, nor any special skill required. Only a test-tube and
a supply of pellets are necessary by this method, which may be used by the most
unskilled and ignorant.
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 the use of acid or alkaline materials of exact weight in a solid form combined
with some coloring-matter or "indicator" which may be used with only a test-tube
or like appliance for determining the alkalinity or acidity of any substance.
Dated this 12th day of November 1890.
ALFRED WALTER STOKES.