Improvements in the Manufacture of Sulphocyanides.
Year: 1893

page_text: Date of Application, 22nd Sept., 1893
Complete Specification Left. 11th June, 1894-Accepted, 14th July, 1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Sulphocyanides.
We, HORACE WOODWARD CROWTHER, of The Beeches, West Bromwich, and
EDMUND CHARLES ROSSITER, of Church Lane, Smethwick, both in the County
of Stafford, Analytical Chemists, do hereby declare the nature of this invention to
be as follows:-
In the well known Gèlis process only about 33 per cent. of the ammonia employed
is converted into sulphocyanic acid, the remainder of the ammonia being necessary
to combine with the sulphocyanic acid and sulphuretted hydrogen, and in the
Specification of the English Patent No. 5354 dated March 25th 1891 it is proposed
to convert the whole of the ammonia into sulphocyanic acid by means of manganese
dioxide or Weldon mud or ferric hydrate either with or without the addition of lime
or other base to form sulphocyanide of lime or of the other hase used. The
manganese dioxide or ferric hydrate being employed in order to prevent excessive
pressure.
We have found that when sufficient lime in the form of milk of lime to combine
with the whole of the sulphocyanic acid and hydrogen sulphide produced during
the reaction is present the addition of manganese dioxide or of any other compound
which forms an insoluble sulphide or any oxidising agent similar in its action
to MnO, is unnecessary.
We proceed as follows.
We take liquor ammonia, carbon bisulphide, lime, baryta, magnesia, strontia,
soda or potash, either dissolved or suspended in water in proportions so that the
whole of the ammonia is converted into sulphocyanic acid and the lime or other
material is sufficient to combine with the whole of the sulphocyanic acid and to
form sulph-hydrate with the sulphuretted hydrogen as expressed in the equation—

page_text: such as soda or potash to make the sulphocyanide of lime first and then precipitate
the sulphocyanide of lime with carbonate or sulphate of soda or potash.
Instead of the alkaline carths and alkalis their sulphides may be employed.
Dated this 22nd day of September 1893.

page_text: the autoclave is run into a vessel or vessels and treated with carbonic acid
preferably limekiln gases to convert the sulphydrate into carbonate or bicarbonat e
A series of vessels similar to those used in the Chance process for the recovery of
sulphur from alkali waste is well adapted to this purpose. This apparatus is
described in the Specification of a Patent No. 8666 in the year 1887. The HS
evolved may be either burnt into SO, for the manufacture of sulphuric acid or
converted into free sulphur by a web known process. The carbonate of lime or
other alkaline earth or bicarbonate of the alkali is separated by filtration and
washed.
If the caustic alkalies, soda and potash are used, the carbonation of the
sulphydrate is more difficult and expensive and especially when potash is used a
large quantity of carbonate is left in solution; but we have found that these
carbonates separate during the concentration of the solution leaving a pure
sulphocyanide which can be decanted off.
In practice if we desire to produce the sulphocyanides of sodium or potassium we
prefer to make sulphocyanide of lime first and then prepare from this the sulpho-
cyanide of the alkali by double decomposition with carbonate or sulphate of the
alkali.
Instead of the oxides or hydrates mentioned the corresponding sulphides may be
employed, the reaction in this case is represented (for instance) by the following
equation.
HORACE WOODWARD CROWTHER.
EDMUND CHARLES ROSSITER.