IMPROVEMENTS IN THE MANUFACTURE OF ACETATE OF SODA AND OTHER ACETATES
Year: 1881

page_text: LETTERS PATENT to William George Forster, of Pilham Villa, Streatham
Common, in the County of Surrey, for an Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF ACETATE OF SODA AND OTHER ACETATES,"
PROVISIONAL SPECIFICATION left by the said William George Forster at
the Office of the Commissioners of Patents on the 31st March 1881.
WILLIAM GEORGE FORSTER, of Pelham Villa, Streatham Common, in the County
of Surrey. "IMPROVEMENTS IN THE MANUFACTURE OF ACETATE OF SODA AND
OTHER ACETATES."
At the present time acetate of soda is obtained by adding sulphate of soda in
solution to a solution of acetate of lime. The solution of acetate of lime is obtained
by mixing a thin cream of slaked lime and water with crude pyroligneous acid
and contains various impurities. · The acetate of soda obtained in this way is
impure and has to be purified by repeated crystallizations, and also by being fused
so as to carbonize the matters which render it impure. The fusing of the impure
acetate of soda, so as to carbonize the impurities without injuring the acetate of
soda, is a difficult operation, and requires considerable skill, as frequently the
impurities contained in the acetate of soda render it difficult to fuse, and it is.
difficult to obtain in this way a pure acetate of soda.
According to my Invention I add to impure acetate of lime a small proportion
of water and pass through it hydrochloric acid vapour: or in place of this I might
add to impure acetate of lime hydrochloric or other acid: I also add to the solutions
so obtained spirit of wine, or amvlic or methylic alcohols, known commonly by
the names of fusil oil and wood spirit. I then distil the solution in a still, and (if
spirit of wine has been used) I obtain acetic ether mixed with butyric and other
ethers. Afterwards I separate the acetic ether from the other ethers by distillation.
To the acetic ether so obtained I add a caustic alkali, such as lime. soda, or
potash, or a mixture of any of them, and heat them in a still generally, I use

page_text: caustic lime together with a small quantity of caustic soda. I thus obtain spirits
of wine which may be condensed and recovered, and acetate of lime together with
a little acetate of soda; or if lime only is used, acetate of lime is alone obtained.
The acetate of lime mixed with a little acetate of soda I convert into a pure and
readily fusible acetate of soda by the addition to it of sulphate or carbonate of
soda. The solution of acetate of soda so obtained may be crystallized and then
gives a pure acetate of soda: or the solution may be evaporated to dryness and at
once fused without difficulty.
In the above way also a pure acetate of lime or other acetate may be obtained.
The butyric and other ethers recovered in the above process may be utilized in
various ways.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William George Forster in the Great Seal Patent Office on the
29th September 1881.
WILLIAM GEORGE FORSTER, of Pelham Villa, Streatham Common, in the County
of Surrey. IMPROVEMENTS IN THE MANUFACTURE OF ACETATE OF SODA AND
OTHER ACETATES."
At the present time acetate of soda is obtained by adding sulphate of soda in
solution to a solution of acetate of lime. The solution of acetate of lime is obtained
by mixing a thin cream of slaked lime and water with crude pyroligneous acid
and contains various impurities. The acetate of soda obtained in this way is
impure and has to be purified by repeated crystallizations, and also by being fused
so as to carbonize the matters which render it impure.
The fusing of the impure acetate of soda. so as to carbonize the impurities
without injuring the acetate of soda, is difficult operation, and requires con-
siderable skill, as frequently the impurities contained in the acetate of soda
render it difficult to fuse, and it is difficult to obtain in this way a pure acetate
of soda.
According to my Invention I add to impure acetate of lime a small proportion
of water and pass through it hydrochloric acid vapour; or in place of this I might
add to impure acetate of lime hydrochloric or other acid; I also add to the
solutions so obtained spirit of wine, or amylic or methylic alcohols, known
commonly by the names of fusil oil and wood spirit. I then distil the solution
in a still, and (if spirit of wine has been used) I obtain acetic ether mixed with
butyric and and other ethers. Afterwards I separate the acetic ether from the other
ethers by distillation.
To the acetic ether so obtained I add a caustic alkali, such as lime, soda, or
potash, or a mixture of any of them, and heat them in a still generally, I use
caustic lime together with a small quantity of caustic soda. I thus obtain spirits
of wine (which may be condensed and recovered), and acetate of lime together
with a little acetate of soda; or if lime only is used, acetate of lime is alone
obtained.
The acetate of lime mixed with a little acetate of soda I couvert into a pure and
readily fusible acetate of soda by the addition to it of sulphate or carbonate of
soda. The solution of acetate of soda so obtained may be crystallized and then
gives a pure acetate of soda; or the solution may be evaporated to dryness and at
once fused without difficulty.
In the above way also a pure acetate of lime or other acetate may be obtained.
The butyric and other ethers recovered in the above process may be utilized in
various ways.
Having thus described my Invention. I would state that I am aware that it
was before known that the acids of the fatty series might be converted by means
of the alcohols and hydrochloric and other acids into corresponding ethers, and
also that these ethers might be converted back again into the respective alcohols
and acids; but by my Invention I apply these well known chemical facts, in the
manner herein before described, to the separation of acetic acid from the other
acids contained in impure acetate of lime made from pyroligneous acid obtained
by the distillation of wood, and am thereby able to produce an acetate of lime
capable of at once yielding pure acetic acid fit for food purposes, or to at once
produce pure acetate of soda, potash, or such like,

page_text: What I claim is the manufacture of acetate of soda and other acetates,
substantially in the manner herein before described.
In witness whereof. I, the said William George Forster, have hereunto set
my hand and seal, this Twenty ninth day of September, in the year of
our Lord One thousand eight hundred and eighty-one,
W. G. FORSTER. (...)