AN IMPROVED METHOD OR PROCESS OF PURIFYING HYDRATE OF STRONTIUM to be as follows
Year: 1885

page_text: OF CO
I, EUGENE FRANÇOIS TRACHSEL, of 45 Miranda Road, Holloway, in the
County of Middlesex, Chemist, do hereby declare the nature of my invention for
"AN IMPROVED METHOD OR PROCESS OF PURIFYING HYDRATE OF STRONTIUM
to be as follows:-
"
Heretofore, in the purification of hydrate of strontium, obtained from the
sulphate of strontium, the said hydrate has had to be repeatedly crystallized to
free it from iron and sulphide, and render it fit for use.
My invention consists in an improved process which comprises the drying of the
impure hydrate-crystals by a slow and gentle heat, so that, instead of containing
only 39 per cent of anhydrous-oxide, they contain above 50 per cent of the same.
By this treatment, the sulphide of iron contained in the crystals is oxidized, and
the sulphide of strontium is changed into hyposulphite, whilst about 2 per cent of
the hydrate of strontium is changed into carbonate, through the action of the
carbonic acid of the atmosphere.
When these dried crystals are dissolved in hot water, the carbonate of strontium
precipitates the iron, now in the state of oxide, and the hyposulphite of strontium,
which is colourless, remains in the mother liquor; the liquor is then cooled down
and the hydrate crystallized out.
I thus obtain, by one crystallization, a pure white hydrate of strontium fit for
use without further treatment.

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of Strontium.
I, EUGENE FRANÇOIS TRACHSEL, of 45 Miranda Road, Holloway, in the
County of Middlesex, Chemist, do hereby declare the nature of my invention for
"AN IMPROVED METHOD OR PROCESS OF PURIFYING HYDRATE OF STRONTIUM "
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:―
Heretofore in the purification of hydrate of strontium (Sr (OH)2 + 8 H₂ O)
oltained from the sulphate (or impure carbonate) of strontium, the said hydrate
has had to be repeatedly crystallized to free it from iron and sulphide, and render
it fit for use.
My invention consists in an improved process which comprises the purification of
impure hydrate crystals by drying them, preferably in a muffle furnace, so that tho
proportion of anhydrous oxide therein will be increased, that is to say, instead of
containing only about 37 per cent. of anhydrous oxide, they will contain from
about fifty (50) per cent. to about seventy (70) per cent. according to the degree of
impurity of the crystals. I prefer, however, in ordinary cases, that the amount of
anhydrous oxide should be from about 60 to 70 per cent. By this treatment, tho
sulphide of iron contained in the crystals will be oxidized, and the sulphide of
strontium will be changed into hyposulphite, whilst about two (2) per cent. of
the hydrate of strontium will be changed into carbonate, through the action of the
carbonic acid of the atmosphere.
My invention also comprises the solution of these dried crystals in hot water, so
that the carbonate of strontium precipitates the iron, now in the condition of oxide,
and the hyposulphite of strontium, which is colourless, remains in the mother
liquor; the liquor is then cooled down and the hydrate crystallized out.
I thus obtain by one crystallization a colourless, or nearly colourless, and pure
hydrate of strontium fit for use without further treatment.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
First. The purification of the impure crystals of bydrate of strontium by drying
the same, as, and for the purpose, specified.
Second. The above described improved process, viz:-the drying of impure
bydrate of strontium, and thus obtaining a product, which is subjected to one
crystallization and thereby yields colourless, or nearly colourless, and pure crystals
of hydrate of strontium, as above set forth.
Dated this 14th day of October 1885