IMPROVEMENTS IN THE MANUFACTURE OF SULPHUR COMPOUNDS
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by William Ramsay at the Office of the
Commissioners of Patents on the 17th March 1883.
WILLIAM RAMSAY of University College City of Bristol Professor of Chemistry
"IMPROVEMENTS IN THE MANUFACTURE OF SULPHUR COMPOUNDS'
"
This Invention cousists in the use of solutions of the sulphites of sodium,
potassium, or ammonium for the absorption of sulphurous acid (S. O₂) from flue-
gases, or chimney gases. Instead of or in conjunction with the above mentioned
solutions, the solid salts may be used, or caustic soda, potash or ammonia, or their
carbonates, these being converted into sulphites by the process of absorption; or
the tribasic phosphates of sodium or potassium, in solution, or solid-The
sulphurous acid (S.O,) forms with these salts, acid sulphites, from which the acid
may be expelled by heat; and it is thus possible to separate sulphurous acid from
other gases which do not form compounds with the above mentioned substances
The flue or chimney-gases, containing sulphurous acid, after being cooled, and
washed, are (1) led through absorbing towers filled with coke, or pumice-stone,
or other porous material kept moist by a solution of one of the above-mentioned
salts, or (2) are bubbled through such solutions; or (3) are led or passed over such
salts in the solid form-The sulphurous acid is thus absorbed and the solution or
solid, containing dissolved or combined sulphurous acid, on issuing from the towers,
or if in the solid state, when saturated with the gas, is heated by suitable means,
to expel the sulphurous acid, when the solution or solid may be again used for
fresh absorption of gas By this means the sulphurous acid is obtained pure or
nearly pure
The gas may be converted into liquid sulphurous acid, by passing it through
tubes or chambers cooled to a low temperature; or it may be mixed with oxygen,
or air, and converted into sulphuric acid, by leading the mixture over finely
divided platinum or other suitable material, at a red-heat by known processes; or
it may be used in the preparation of solutions of sulphurous acid, or sulphites, by
causing it to be absorbed by water, or by the oxides, hydro-oxides, or carbonates
of metals.
This process forms a means of separating sulphurous acid from the flue-gases of
pyrites-burners or sulphur burners; or from the gases evolved during the roasting
of ores of metals containing sulphur; or during the combustion of sulphuretted

page_text: hydrogen; or by the combustion of coal or coke or from mixtures of gases
containing sulphurous acid, however obtained
When sulphurous acid is mixed with air, and led over heated platinum, or other
substance capable of inducing combination between the oxygen of the air and the
sulphurous acid, a portion of the sulphurous gas is oxidised to sulphuric acid-
The sulphuric acid formed is condensed by bringing it in contact with water;
and the escaping gases, which consist of a mixture of oxygen, nitrogen and
sulphurous acid are deprived of the sulphurous acid by means of one or more of
the above absorbents; the sulphurous acid thus becomes available for a secoud
operation of the same kind.
This process permits of the direct utilisation of the products of combustion of
sulphuretted hydrogen; these, mixed with a sufficient supply of air are led over
heated platinum, and partially converted into sulphuric acid; and the uncombined
sulphurous acid is recovered as above mentioned, and again utilised, either in the
manufacture of sulphuric acid, or for one of the purposes mentioned above
'