Dictionarium Polygraphicum. A transparent BLUE from Mr. Boyle equal to ultramarine

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol I.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
This is a beautiful Blue, and the chief ingredient of which it is made, is the cyanus or blue cornbottle flower, which abounds almost in every corn field, and may easily be had, during four of the summer months; and may be gathered by children about the skirts or verges of corn fields, without doing any damage to the corn.

This flower has two blues in it, one of a pale colour in the larger outward leaves, and the other of a deeper Blue that lies in the middle of the flower.

Both these will do, being separated from the buttons or cases, in which they grow; but the deep blue leaves in the middle produce by much the best colour; which may be observ’d by rubbing the leaves while they are fresh, so hard upon a piece of good writing paper, as to press out the juice, and it will yield an excellent colour, which will not fade, as has been found by the experience of two or three years.

This part of the flower is therefore the principal and what may be depended upon; which should be pick’d from the rest of the flower leaves, the same day, if it may be, or the next, or as soon as possibly can be.

A good quantity of these middle leaves being procur'd, press out what juice you can from them, and add to it a little alum, and you will have a lasting, transparent Blue, of as bright a staining colour as can be desired, scarce inferior in beauty to ultramarine, and is durable.

As for the outward flower leaves which are paler, it is not certain that they will answer the end; but upon some trials being made, that may also be known.

Let the flowers be gathered about the beginning of june, or in July or August, and some may be found in May; but the preparation of the colour by picking out the middle deep blue flower leaves, and presfing out the juice, must be press'd cut with all the expedition possible, or they will lose their perfections.

It is very probable, that if the chives of these blue corn-bottle flowers were cur'd in the same manner as saffron is, they would produce a much greater body of colour, from which a tincture might be drawn with more ease, than if pressed raw or fresh from the field.

In order to do this, such a kiln should be prepar'd as is us’d for curing of saffron, in which may be made a small charcoal fire, which will communicate an heat to the top of the kiln, which is to be covered with an hair cloth; upon which should be laid four or five sheets of white paper, such as is us'd in curing of saffron; then a parcel of the picked flowers are to be laid on to the thickness of two or three inches, laying close and flat with a knife, and sprinkling with some thin gum water; then the cake of flowers is to be covered with two or three more sheets of paper and a board with a small weight laid on for a few minutes; after which the board is to be taken off, and the cake of flowers to be turn'd upon the kiln, taking hold of all the papers with both hands; and when it has been rightly plac'd, take off the upper papers, and sprinkle the cake again with some thin gum water; and then settling the cake of flowers again with a knife, let the papers be laid on again with the board and weight for a minute or two, and then let the papers be turn’d again and again, till the cake of flowers becomes united, and of the thickness of a cake of saffron.

In this operation, you will find the flowers to grow darker and darker every time they are turned, till at length the cake will look of a deep Blue tending to black. From whence a tincture may be easily drawn.

During this operation, great care must be taken that the fire does not scorch the flowers; but that it be as constant and gentle as may be, which will be a sure way to bring the flower cake to a good colour.

But it will not be improper for any person, who shall under take the curing of this colour, to consult the methods of curing faffron, of which they may be inform’d, either by a treatise of the method of curing saffron, written by Dr. Dowglass, or another by Mr. Bradley in his monthly treatise of husbandry and gardening.

If it should be objected, that it will be troublesome to make this BLUE COLOUR; let it be confidered what pains and nicety there is in gathering and curing of saffron; which is fometimes sold at thirty shillings per pound, and seldom comes up to three pounds per pound. But this Blue, if it comes up to the colour of ultramarine, will be worth four or five pounds er ounce, especially when it stains so well as this does.

Therefore it would, in all probability, be worth the while to have a piece of ground on purpose for this use, where nothing else but this cyanus or corn-bottle should be sown; and whereas this flower is said to be plentiful enough in the fields between Twickenham and Teddington in Middlesex, so there might easily be seed enough procured for that purpose in half an hour's time to sow an hundred acres.

As to the manner of cultivating this plant, every knob or head of seed must be opened before it is sown, for each head contains a great number of seeds; as for the preparing of the ground to receive this seed, there need to be no more trouble and expence than common plowing requires; which being done, the seed is to be sown either at the latter end of August, which will come up soon enough to stand the winter, and blossom parly the May following; or else it may be sown at the end of March, and it will begin flowering the june following.

At either of these seasons, after the ground has been well plough'd, harrow it in with bushes, and it will come up in a little time.

As to the choice of this seed, it will be necessary that it be gathered only in such fields, where you are sure there grows no corn-bottles of any other colour but blue; and then all the plants which rise from such seed, would produce Blue; but if they should be gathered in such places where there are varieties of them, then various sorts are to be expected, as white, red, or purple, altho' we are sure we gather the seed from such as were truly of a blue sort; for if there is a red flower of the same tribe growing near it, the difference of the colour will be so in termixt between both, that the seed of both will bring a variety from the principal, depending on the colours of both.

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