The chemical history of ammonia commences in Egypt with Sal
Ammoniac. This is mentioned by Pliny under the name of Hammoniacus
sal. Dioscorides also alludes to it; but in neither case does the
description given fit in satisfactorily with the product known to us.
Dioscorides, for instance, states that sal ammoniac is particularly
prized if it can lie easily split up into rectangular fragments. It
has been conjectured that what was called sal ammoniac by the ancient
writers was, at least sometimes, rock salt.
The name is generally supposed to have been derived from that of the
Egyptian deity, Amn or Amen, or Ammon as the Greeks called him, and
in the belief that he was the same god as Jupiter he is referred to
in classical literature as Zeus-Ammon or Jupiter-Ammon. The principal
temple of this god was situated in an oasis of the Libyan desert which
was then known as Ammonia (now Siwah), and if, as is supposed, the
salt was found or produced in that locality its name is thus accounted
for. Gum ammoniacum was likewise so called in the belief that it was
obtained in that district, though the gum with which we are familiar
and which comes from India and Persia, is quite a different article
from the African gum the name of which it has usurped. Pliny derives
the name of the salt from the Greek “ammos,” sand, as it was found in
the sand of the desert; an explanation which overlooks the fact that
the stuff was called by a similar name in a country where the sand was
not called ammos. In old Latin, French, and English writings “armoniac”
is often met with. This was not inaccurate spelling; it was suggested
by the opinion that the word was connected with Greek, armonia, a
fastening or joining, from the use of sal ammoniac in soldering metals.
That Pliny did sometimes meet with the genuine sal ammoniac is
conjectured by his allusion to the “vehement odour” arising when lime
was mixed with natrum. Probably this natrum was sal ammoniac. Among the
Arabs the term sal ammoniac often means rock salt; but in the writings
attributed to Geber, some of which may be as late as the twelfth or
thirteenth century, our sal ammoniac is distinctly described. It is
also exactly described by Albertus Magnus in the thirteenth century,
who mentions an artificial as well as a natural product, but does not
indicate how the former was made. From this time sal ammoniac became
a common and much-prized substance in alchemical investigations, as
from it chlorides were obtained. The “volatile spirit of sal ammoniac”
was made by distilling a solution of sal ammoniac with quicklime, and
of course the same product was obtained in other ways, especially
by distilling harts’ horns, and this was always regarded as having
peculiarly valuable properties. A “sal ammoniacum fixum” was known to
the alchemists of the fifteenth century. It was obtained as a residue
after sal ammoniac and quicklime had been sublimed. It was simply
chloride of calcium.
The so-called natural sal ammoniac was for centuries brought from
Egypt, and was supposed to have been mined in the earth or sand of
that country. In 1716 the younger Geoffroy came to the conclusion
that it must be a product of sublimation, and he read a paper to the
French Academy giving his reasons for this opinion. Homberg and Lemery
opposed this view with so much bitterness, however, that the paper was
not printed. In 1719 M. Lemaire, French Consul at Cairo, sent to the
Academy an account of the method by which sal ammoniac was produced in
Egypt, and this report definitely confirmed the opinion which Geoffroy
had formed. It was, said M. Lemaire, simply a salt sublimed from soot.
The fuel used in Egypt was exclusively the dung of camels and other
animals which had been dried by the sun. It consisted largely of
sal ammoniac, and this was retained in the soot. For a long time an
artificial sal ammoniac had been manufactured at Venice, and a commoner
sort also came from Holland. These were reputed to be made from human
or animal urine. The manufacture of sal ammoniac was commenced in
London early in the eighteenth century by a Mr. Goodwin.
A formula for Sal Ammoniacum Factitium in Quincy’s Dispensatory (1724)
is as follows:--Take of Urine lb. x.; of Sea-salt lb. ii.; of Wood soot
lb. i.; boil these together in a mass, then put them in a subliming
pot with a proper head, and there will rise up what forms these cakes.
Dr. James (1764) states that at Newcastle one gallon of the bittern or
liquor which drains from common salt whilst making, was mixed with 3
gallons of urine. The mixture was set aside for 48 hours to effervesce
and subside. Afterwards the clear liquor was drawn off and evaporated
in leaden vessels to crystallisation. The crystals were sublimed. A
sal ammoniacum volatile was made by subliming sal ammoniac and salt of
tartar (or lime or chalk) together. Sometimes some spices were put into
the retort. This salt was used for smelling-bottles. Aqua regia was
made by distilling sal ammoniac and saltpetre together.
Sal Volatile Oleosum was introduced by Sylvius (de la Boe) about the
year 1650. It became a medicated stimulant of the utmost popularity,
and there were many formulas for it. One of the most famous was
Goddard’s Drop. (See page 319).
Ammonia in gaseous form was first obtained by Priestley in 1774.
He called it alkaline air. Scheele soon after established that it
contained nitrogen and Berthollet proved its chemical composition in
1785.