IMPROVEMENTS IN BLEACHING AND PURIFYING PARAFFIN
Year: 1867

page_text: PROVISIONAL SPECIFICATION left by John Fordred at the Office of the
Commissioners of Patents, with his Petition, on the 26th September
1867.
I, JOHN FORDRED, of Blackheath, in the County of Kent, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN BLEACHING AND
PURIFYING PARAFFIN," to be as follows:-
Having melted the crude paraffin, and allowed the mechanical impurities.
to subside in the usual way, I run the liquid paraffin into a vessel, and having
raised the temperature to 260° Fah'. or thereabouts, I add thereto sulphuric.
acid and agitato the mixture well (preferring hot air for that purpose), I then
keep it warm to allow the tar and coloring matters to deposit. After it has.
become clear I draw it off from the sediment and boil it in contact with a
weak solution of glue, by the aid of free steam, until the glue has taken
up and combined with any free sulphuric or sulphurous acid the liquid
paraffin may contain; or it may be washed with the solution of glue by
mechanical means. On allowing the whole to repose the liquid paraffin will
become transparent and bright. Or in lieu of this glue treatment I draw off
the clear liquid paraffin and mix it with ground fullers' earth, agitate it, and
allow it to settle. It is then drawn off and mixed with about 15 per cent.
When
of spirit (more or less) and run into tins and allowed to cool.
thoroughly set the cakes are submitted to hydraulic pressure in the usual
way, and finally filtered through animal charcoal, as is well understood.

page_text: As by the process above described the greater part of the coloring matter
is extracted by the acid and glue, a much smaller quantity of spirit is required
to be used in the pressing operation than is now necessary. If the crude
paraffins are very foul the bleaching process may be repeated, and the
pressing with spirit may also be repeated.
I sometimes dispense with the use of spirit or other solvent. To effect this I
proceed as follows:-After removing the principal colouring matters by the aid
of chemicals,.and submitting the cakes alone and without admixture of spirit
to cold hydraulic pressure, which I call dry pressing, the cakes are remelted and
cooled, and pressed again in a hot hydraulic press as is practised in the manu-
facture of stearine, and this is repeated till they are sufficiently white and
hard to pass through the charcoal. Ground fullers' earth or a good
argillaceous clay or marl, preferring that having a blueish cast, may replace
the use of animal charcoal as a bleaching agent in the above processes, or in
the ordinary spirit process. If fullers' earth be used to clarify the acidified
paraffin the product may be washed with steam immediately, or at some other
stage of the process.
When desirable to economize the sulphuric acid I extract the tar and
principal coloring matters by treating the crude paraffin with about 2 per
cent. only of the acid in the first instance. I then steam with the glue
solution, run into tins and dry press, this gets rid of the heavy oil. I then
remelt the cakes, and treat again with acid and steam, and proceed as above.
The sulphuric acid may also be warmed; previously to its being added to the
liquid paraffin.
In order to cleanse the cloths I wash them in spirit and pass them through
rollers or press them.
I sometimes replace the glue solution by milk, flour, albumen, or other
bodies of like nature.
In order to shield the paraffin from undue action of the sulphuric acid I
sometimes mix with it fullers' earth or ground soda, or the like, previously
to the addition of the acid to the liquid paraffin.