Improvements in the Manufacture of Anhydrous Zinc Chloride.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Anhydrous Zinc Chloride.
We, OSCAR JULIAN STEINHART and JULIUS LEONARD Fox VOGEL, both of
91, Blackfriars Road, in the County of Surrey, Electro Chemists, and HENRY
ERNEST FRY, of 5, Laurence Pountney Hill, in the City of London, Mineral Mer-
chant, do hereby declare the nature of this invention to be as follows:-
When a solution of zinc chloride is evaporated in an open vessel, and has
reached such a concentration that its boiling point has risen to about 180° C,
no further dehydration can be obtained without an evolution of hydrochloric
acid, and although the heating is continued for a long period, it is impossible
owing to the hygroscopic nature of the salt, to get rid of the last 3 or 4 per cent. of
water, although hydrochloric acid continues to be given off by the decomposition
of the water with the accompanying formation of oxychloride of zinc.
The object of this invention is to avoid as much as possible this formation of
oxychloride of zinc with its accompanying loss of chlorine, and also to dehydrate
the zinc chloride nearly completely.
This is effected by causing the water vapour to be removed as quickly as
possible from the surface of the melted salt as it is evaporated off from it. To
effect this we convey the concentrated solution of zinc chloride (before it com-
mences to give off hydrochloric acid) into an air tight vessel where it is heated
under a partial vacuum either with or without a current of dry air.
Dated this 19th day of September 1898.
0. J. STEINHART,
JULIUS L. F. VOGEL,
HENRY E. FRY.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Anhydrous Zinc Chloride.
We, OSCAR JULIAN STEINILART and JULIUS LEONARD Fox VOGEL, both of
91, Blackfriars Road, in the County of Surrey, Electro Chemists, and HENRY
ERNEST FRY, of 5, Laurence l'ountney Hill, in the City of London, Mineral Mer-
chant, do hereby declare the nature of this invention and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement:-
-
When a solution of zinc chloride is evaporated in an open vessel, and has
reached such a concentration that its boiling point has risen to about 180 degrees
C. no further dehydration can be obtained without an evolution of hydroch-

page_text: loric acid and although the heating is continued for a long period, it is impossible
owing to the hygroscopic nature of the salt to get rid of the last few per cent. of
water, although hydrochloric acid continues to be given off by the decomposition
of the water with the accompanying formation of oxychloride of zinc.
The object of this invention is to dehydrate zinc chloride more effectually than
has hitherto been possible, and at the same time to avoid the loss of chlorine and
simultaneous formation of zinc oxychloride.
According to our invention we introduce the solution of zinc chloride into a
suitable vessel and concentrate in the ordinary way until such degree of concen-
tration has been attained that the zinc chloride if concentrated further would
commence to decompose and in order to avoid this decomposition the process is
from this point completed under reduced pressure. As an alternative method
the solution of zinc chloride may without any preliminary concentration be
introduced direct into a suitable air tight vessel heated by any suitable means
and in which a vacuum is maintained during the whole operation of evaporation.
This is continued until practically all the moisture has been driven off and
practically anhydrous zinc chloride remains in the vessel in the fused state.
In either case air from which all moisture has been previously extracted may
be drawn either over or through the zinc chloride to assist in carrying off the
water vapour.
By effecting or completing the dehydration of zinc chloride under a reduced
pressure in the above way we are enabled to obtain a nearly pure dehydrated
zinc chloride.
Having now particularly described and ascertained the nature of our said in-
vention and in what manner the same is to be performed we declare that what
I claim is
1. The manufacture of dehydrated zinc chloride by boiling a solution of zinc
chloride in a vessel in which a vacuum is maintained.
2. The manufacture of dehydrated zinc chloride by boiling a solution of zinc
chloride in a vessel in which a vacuum is maintained whilst at the same time
a current of previously dried air is drawn over or through the molten chloride.
Dated this 13th day of June 1899.
O. J. STEINHART,
JULIUS L. F. VOGEL,
HENRY E. FRY.