CLASS IX. Of black colours.
Of lamp black.
AMP black is the foot of oil colledted
as it is formed by burning. It is a brownilh black : but neverthelefs, being of a good texture for mixing either with oil or water, and drying well with oil, it is the principal black at prefent ufed in all nicer kinds of painting: for notwithftanding ivory black far furpafles this in colour, the grofs and adulterate preparation of all that is to be now obtained has occafioned it to be greatly rejedted.
The lamp black is made by burning oil in a number of large lamps in a confined place, from whence no part of the fumes can efcape; and where the foot formed by thefo fumes, being colledted againft the top and fides of the room, may be fwept together and colledted : and this being put into fmall barrels is fold for ule without any other preparation.
The goodnefs of lamp black lies in the ful- »efs of die colour and the being free from dull or other impurities. The lightnefs of the fub- itance furnilhes the means of difcovering any a- dulteration if to a great degree: as the bodies with which lamp black is fubjedt to be fophifti- cated are all heavier in a confiderable proportion.
Of ivory black.
Ivory black is the coal of ivory or bone, formed by giving them a great heat *, all accefs of air to them being excluded. It is, when pure, and genuinely prepared from the ivory, a full clear black j and would be the moll ufeful of any, in every kind of painting, but that it is apt to dry fomewhat too llowly in oil. At prefent, neverthelefs, being prepared only by thofe who manufacture it from bones in very large quantities for coarfe ufes, and fell itj at an extreme low price, it is fo grofsly levigated, being ground only in hand or horfe- mills, and adulterated moreover copioully with charcoal dull, which renders it of a blue cafK that it is wholly exploded from all more delicate purpofes, and lamp black ufed in the place of it, though inferior, with regard to the purity and clearnefs of the black colour, to this, when good.
As the ivory black, notwithllariding, has. its merit in moll kinds of painting, when its preparation is properly managed; particularly in water and varnilh : thofe who defire to have it may prepare it themlelves in perfection by the fbU, lowing means.
“ Take plates, chips, or (havings of ivory} ** and loak them in hot linleed oil; or, if filings “ are to be more eafily procured, they may. be <c ufed moillned with the hot oil. Put them. “ into a veflel which will bear the fire; cover- ** ing them with a (ort of lid made of clay and. “ land; which (hould be dried, and the cracks “ repaired before the veflel be put into die fire. “ Procure this veflel to be placed in a tobaccp- ct pipe maker’s or potter’s iurnace, or any other
** fuch
liich fire j and let it remain there during one “ d their heats. When it fhall be taken out, ** the ivory will be burnt properly; and mull be 41 afterwards thoroughly well levigated on the “ Hone with water ; or it Ihould, indeed; to ** have it perfectly good, be alio walhed over.”
Thole who have a calcining furnace, fuch as is defcribed p. 22, may very commodioufly burn the ivory in it; and the fire need not be continued longer than while the fumes, that arife from the veflel containing the ivory, appear to flame. This operation may lifcewilfe be performed in the fubliming furnace de* feribed p. 15, by putting the ivory in a retort coated with the fire-lute and filing the retort as is drrefred p. 32 for the fublimers; and a proper receiver bteing fitted to the receivers, the fumes will be detained in it, and the fmell prevented from being in the Ieaft troublefome: the fire mull in this cafe be continued while mf gtoft fumes come over.
'The goodnefs of ivory black may be perceived* by its full black colour, not inclining tbO- MUeh to blue; and by its finenefs as a powder.
Of blue black.
Bhieblaek is jhecoal of lome kind of Wood, or other Vegetable matter, burnt in a eloleheat Where the air can have no aceefe. The bell hind' is feid to be made of vine flatks and ten-
K 2 drils:
drils : but there are doubtlefs many other kinds of vegetable fubftances from which it may be equally well prepared. It is, when good, a fine bluifh black colour ufeful in moft kinds of paintings for many purpofes ; but is rarely to be had at prefent well prepared, and therefore much neglected in moft nicer cafes.
Thole, who delire to have blue black perfectly good, may prepare it in the manner a- bove directed for the ivory black, from the vine ftalks or tendrils, or any other twigs of wood of an acid tafte and tough texture, but the loaking in oil, prefcribed for the ivory, mult be here omitted.
The goodnefs of the blue black confifts in the cleanncfs and blue call of its black colour; and the perfeCtnefs of its levigation, which Ihould be managed as directed for the ivory black.
Of Indian ink.
Indian ink is a black pigment brought hither from China, which on being rubbed with water, diflolves; and forms a fubftance refembling ink; but of a confidence extremely well adapted to the working with a pencil: on which account it is not only much ufed as a black colour in miniature painting; but is the black now generally made ufe of for all finaller drawings in chiaro obfcuro (or where the effeCt is to be produced from light and lhade only.)
The preparation of Indian ink, as well as . of the other compofitions ufed by the Chinefe as paints, is not hitherto revealed on any good authority; but it appears clearly from experiments to be the coal of fifh bones, or fome other vegetable fubftance, mixed with ilinglafs fize, or other fize; and, moll probably, honey or fiigar candy to prevent its Cracking. A fubftance, therefore, much of the fame nature, and applicable to the fame purpofes, may be formed in the following manner.
“ Take of ifinglafs fix ounces, reduce it to ** a fize, by diflolving it over the fire in double “ its weight of water. 'I’ake then of Spanifh ** liquorice one ounce; and diflblve it alfo in ** double its weight of water; and grind up ** with it an ounce of ivory black, prepared “ as above directed in p. 130. Add this mix- ** ture to the fize while hot; and ftir the “ whole together till all the ingredients be ** thoroughly incorporated. Then evaporate 4> away die water in baleno mariae, and caft ** the remaining compofition into leaden “ moulds greafed j or make it up in any “ other form.”
The colour of this compofition will be e- qually good with that of the Indian ink: the ifinglafs fize, mixt with the colours, works with, the pencil equally well with the Indian ink : and the Spanilh liquorice will both render it eafily diflolvable on the rubbing with water, to which the ifinglafs alone is fome- what relu&ant; and alfo prevent its cracking and peeling off from the ground on which it is laid.