AN IMPROVED BAKING POWDER TO BE EMPLOYED IN THE TREATMENT OF FLOUR IN THE MANUFACTURE OF BREAD AND OTHER FARINACEOUS FOOD
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by John Crawford Walker at the
Office of the Commissioners of Patents, with his Petition, on, the
17th June 1868.
I, JOHN CRAWFORD WALKER, of Surrey Street, Strand, in the County
of Middlesex, do hereby declare the nature of the said Invention for
"AN IMPROVED BAKING POWDER TO BE EMPLOYED IN THE TREATMENT OF FLOUR
IN THE MANUFACTURE OF BREAD AND OTHER FARINACEOUS FOOD," to be as
follows:-
Some of the baking powders heretofore produced, though a great
public convenience, are too expensive to admit of their being carried into
general use, others lodge in the food, into which they enter substances
which are more or less injurious to the alimentary organs; few will
remain uninjured in a moist atmosphere, and none have yet been made
available in the manufacture of bread as light and porous as is generally
required by consumers.
Now the object of this Invention is to produce a baking powder out of
inexpensive materials which will not deteriorate by time, and may be
profitably employed in the manufacture of light bread and other

page_text: farinaceous food without the interposition of ferment, lodging in such
food substances only of a beneficial nature.
The following is an example of the means by which the object of this
Invention may be accomplished, that is to say, amylaceous matter, which
is insoluble in water, may be dissolved in concentrated hydrochloric,
phosphoric, sulphuric, or nitric acid at the ordinary temperature of the
atmosphere. It is also readily dissolved by one of these acids greatly
diluted at a temperature of 212° Fahrenheit. In both cases, while the
acid itself remains unchanged, the amylaceous matter is transformed, first
into dextrin, a soluble substance which resembles gum arabic, and next
into glucose, a species of sugar, which exerts rotation to the right. But
amylaceous matter may be saturated with a diluted acid, and the water
may be evaporated from it before either dextrine or glucose is formed,
leaving the starch or fecula charged with the acid in a comparatively
anhydrous state. Of this fact I take advantage to produce a pulverent
acid and a baking powder, which I employ in the treatment of flour and
the manufacture of bread and other farinaceous food. I saturate
amylaceous matter with what is known in commerce as hydrochloric
acid, diluted so as to contain not more than twenty per cent. of real.
acid. After a brief period the granules of the fecula or starch will
experience exfoliation, and the mass will become stiff. As soon as the
mass has assumed this swollen stiff appearance it is spread in thin layers
upon the shelves of a drying apparatus, and subjected to the influence
of a current of dry air, the temperature of which should not exceed 105°
Fahrenheit. To facilitate evaporation the shelves may be occasionally
withdrawn and the mass broken into lumps. When the water commu-
nicated with the acid has been as nearly as possible evaporated the mass
may be saturated as before and again dried. This process may be
repeated until the amylaceous matter is incapable of retaining more
acid in a comparatively anhydrous state. Thus charged with acid and
dried the amylaceous matter is subjected to mechanical trituration and
a pulverent acid is produced. This substance, which for convenience
may be termed "pulverent hydrochlodric acid," is mixed with bicarbonate
of soda, with due regard to the law of chemical equivalents, so that
when dissolved together, and heat is applied, the carbonate will be
completely decomposed and the acid neutralized. The proper proportions
will be determined from time to time as the materials are manufactured.
This mixture constitutes a "baking powder," from two hundred to three

page_text: hundred grains of which may be incorporated with one pound of flour to
convert the latter into what may be called "self-raising flour." When
the water necessary to convert this flour into dough is added, the acid
of the baking powder held in suspension by the insoluble amylaccous
matter is slowly yielded, and acts so tardily upon the soda of the
carbonate as to allow sufficient time to form the dough into loaves or
paste and place it in the oven before the escape of any appreciable
quantity of gas. On the application of heat the carbonate is totally
decomposed and the acid neutralized. The action which takes place
between the chemical substances brought together by solution results
in double decomposition. The hydrogen of the acid unites with the
oxygen of the soda forming water, while the chlorine of the acid
unites with the sodium forming chloride of sodium or common salt.
The carbonic acid disengaged by this action expanding into the
gaseous form, and escaping at the time the dough is hardening into
bread gives porocity and lightness to the loaf. It is better to keep
the pulverent acid and the carbonate of soda separately and bring them
together in the proper proportions in the self-raising flower, which latter
does not deteriorate by time. When, however, it is desirable to make
the baking powder, and to keep it and sell it as such, the moisture of the
atmosphere may sometimes lead to slight chemical action between the
acid and the soda, unless special means are adopted to prevent such
action. When therefore it is desirable to make a commercial baking
powder to be kept as such for an indefinite period, I render the
bicarbonate of soda employed impervious to the attack of an acid
ordinarily dry in the following manner :-I make what may be termed
a thin gelatinized water by treating amylaccous matter, first, with cold
water, and then with boiling water in the usual way until the granules
have experienced complete exfoliation. So much of this gelatinized
water as may have been made from one pound of fecula or starch is
sprinkled upon about twenty-five pounds of bicarbonate of soda, during
which the mass is continuously and thoroughly stirred. A current of
dry air of a temperature not exceeding 105° Fahrenheit, is then passed
through the carbonate, and the mass is stirred until the water commu-
cated with the amylaceous matter has entirely evaporated, disaggregation
is then effected by very slight trituration, when each crystal of the
carbonate will be found coated with a layer of amylaceous matter, which
as already intimated protects the soda from an attack of pulverent acid,
even under the influence of a moist atmosphere. The pulverent acid

page_text: hercin-before described and the bicarbonate of soda thus treated are
mixed together in such proportions as that the acid of the former shall
furnish a chemical equivalent for the soda of the latter, and the baking
powder is perfect and ready for use in any way.
I do not propose to confine myself to hydrochloric acid as the only
agent employed in my process to decompose the carbonate of soda, but
may substitute any other acid that will act as well; or I may mix with
or dissolve in the hydrochloric acid employed any other acid or any acid
salt which I may deem it advisable to use, having due regard to the
principle involved in my process. I may also substitute any other
carbonate for the carbonate of soda, and any other gelatinized water for
that made from amylaceous matter, if I find it advisable to do so, the
principle being the same in all cases.