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to answer better for the ripening of wall-fruit than those of lightercolours. 6. It is not, however, to be affirmed that the like dif-ferences obtain in the impressions made by common lire. Blackpaper, held to the fire, does not seem to be affected sooner, or ina greater degree, than such as is white. It may be proper to ob-serve also, that the combustibility of the paper may be increased,bv impregnating it with substances of themselves not combustible,and which give no colour to it. This is the foundation of one ofthe sympathetic inks, as they are called, made of a strong solutionof sal ammoniac in water, which, though colourless when writtenwitli on paper, becomes very legible on exposing the paper to thetire; that is, it occasions the parts moistened with it to' scorcli orburn, before the rest of the paper is hurt, to a brown or black.All the salts I have tried produced this etfecl in a greater or lessdegree ; nitre, alum, tartar very weakly ; sea-salt more strongly ;lixed alkaline salts still more so ; sal ammoniac the most stronglyof all. Metallic solutions, made in acids, and diluted so as not tocorrode the paper, acted in the same manner. 7. Besides thesimple blacks, tlu-re are a multitude of compound ones, incliningmore or less to other colours. Thus the painters have blue-blacks,brown-blacks, &c. which may he made by mixing pigments ofthe respective colours with simple black ones, in greater or lessquantity, according to the shade required.
Black, Ivory, otherwise called velvet-black, is burnt ivoryor hones, which, becoming quite black, and being reduced to thinplates, are ground in water, and made into troches, to he usedbv painters, and by jewellers, who set precious stones, to blackenthe ground of the collets, and give the diamonds a teint or foil.In order to be good, it ought to be tender, friable, and thoroughlyground.
Black, Hart’s, that which remains in the retort afterthe spirits, volatile salt, and oil, have been extracted from hart’s-horn. It answers the purposes of painters almost as well as ivory-black.
Black, Lamp , (originally, perhaps, the soot collected fromlamps,) is generally prepared by melting and purifying resin orpitch in iron vessels; then setting fire to it under a chimney, orother place made for the purpose, lined with sheepskins, &e toreceive the vapour or smoke ; in this way vast quantities of it are>repared at Baris. In England it is prepared at the turpenlTie-louses, from the dregs of the resinous matters which are manu-factured there ; hut the greater part of lamp-black is brought fromGermany, Sweden, and Norway ; where the process, in the pre-paration, is dependant on the manufacture of common resin.
Black, Joseph, an eminent chemist, was born at Bourdeaux,in France, of British parents, in 1728. He received Ills educationfirst at Belfast, and afterwards at Glasgow , where he studied phy-sic, and took his doctor’s degree in 1754. Soon after lie was ap-pointed professor of anatomy, and lecturer on chemistry; hut aslie did not deem himself qualified to discharge the duties of theformer station, he exchanged it for the professorship of medicine.In 1756, he published a paper, in which he proved the existenceof what he called fixed air; an important discovery, which cer-tainly paved the way to unparalleled advances made on this subjectby Cavendish, Lavoisier, &c. Next year produced Ivs admiredDoctrine of Latent Heat , which is of the utmost consequence inchemistry. This raised his reputation exceedingly, in consequenceof which he was elected successor to Dr. Cullen, in the chemicalchair at Edinburgh , and from that time devoted himself whollyto that science, and the improvement of his pupils. He died in1799. He was the author of an inaugural dissertation on takinghis doctor’s degree de acido a cibis orto ; “ Experiments on Mag-ne.-ia and Quick Lime ; Observations on the Beady Freezing ofBoiled Water;” these are in the Philosophical Transactions ; AnAnalysis of some Boiling Water in Iceland , in the Memoirs ofthe Royal Society of Edinburgh. His lectures on Chemistry were published in 2 vols. 4lo. 1803, by Dr. Robinson, who pre-fixed to them a memoir of the author. These lectures contain anaccount of the two great discoveries of Latent Heat , and FixedAir.
Black, in heraldry, is stiled Sable. See Heraldry.
Black Act. the statu e of 9 Geo. I. c. 22. is commonly calledthe Waltham black act, because it was occasioned by the devas-tations comnv.tted near Waltham in Essex, by persons in disguise,with their faces blacked. By this statute it is enacted, that per-
sons hunting armed and disguised, and killing or stealing deer, orrobbing warrens, or stealing fish out of any river, &c. or any per-son unlawfully' hunting in liis majesty’s forests, &c. or breakingdown the head of any fish-pond, or killing, &c. cattle, or cut-ting down trees, or setting tire to house, barn, or wood, or shootingany person, or sending letters either anonymous or signed with afictitious name demanding money, &c. or rescuing such offenders,are guilty of felony, without benefit of clergy. This act is madeperpetual" by 31 Geo. II. c. 42.
Black Art, the pretended art of Necromancy , or dealing withevil spirits.
Black Bar, in law, a plea obliging the plaintiff to assign theplace of trespass.
Blackberry, in botany'. See Rubus .
Black-Bird, in ornithology. See Turdus.
Black Book, a book kept in the Exchequer, in which theorders of that court are entered.
BI.ACKBl’RNIA, a genus of the tetrandriamonogvnia classand order. Calyx four-toothed; petals four; anther heart-shaped; germ conic ; stigma simple; berry one-seeded. Thereis oil- species, a native of Norfolk Island .
BLACKBURN, a flourishing town in Lancashire , seated on theBlackwater, near the river Derwent, and containing about 10,000inhabitants. It lies 12 miles E. of Preston , and 203 N. N. W. ofLondon . Lon. 2. 35. W. Lat. 53. 42. N.
Black Cap, in ornithology. See Motacii.la.
Black Cattle, among graziers, denotes all the larger kinds ofdomestic animals which contribute to our support or convenience ;such as oxen, cows, horses, &c.
Black Cock. See Tetrao.
Black Eagle. See Ealco.
Black Eunuchs, in the customs of eastern nations, are Ethio-pians castrated, to whom their princes commit the care of theirwomen. See Eunuch.
BLACKBURN E, Francis, author of “ The Confessional”, aclergyman of the church of England , was born at Richmond, inYorkshire , 1705. After leaving Cambridge, he was inducted in1739, into the living of Richmond, his native place, where lie de-voted himself carefully to the duties of his office, and in the year1750, was made Archdeacon of Cleveland, and Prebendary ofBillon. But imbibing sentiments in a great measure hostile to theestablished forms in the church, particularly respecting subscription,baptism, and the important and fundamental article of the doc-trine of the Trinity, his farther promotion was prevented. He con-tinued, however, to discharge his clerical duties till his death, whichtook place in 1787. liis son, F. Blackhurne, LL. D. publisheda complete collection of his father’s works in 1804, in sivenvoK 8vo. to which for a farther account we refer our readers.
Black Forest, a forest Of Germany, in Suabia , extendingfrom N. to S. between Ortnau, Brisgaw, part of the kingdom ofWirtemberg , the principality of Euslemburg towards the sourceof the Danube, as far as the Rhine above Basil . It is part ot theancient Hercynhm forest.
Blacr Friars, a name given to the Dominican order; calledalso predicants and preaching friars ; in France Jacobins .
BlackJack, or Blend, is a mineral called also false galena,blinde, &c See Blinde.
Blacking is a term sometimes used to signify a factitious black ;as shoe-black, &c. A mixture of ivory or lamp-black with lin-seed oil makes the common oil-blacking. For a shining wateryblacking, small beer is used in the proportion of about a pint totwo ounces of ivory black, with the addition of half an ounce ofbrown sugar, and a quarter of ounce of gum arabic; if a smallquantity of vitriolic acid he added, it will considerably improvethe composition. 'The white of an egg substituted for the gummakes the black more shining; hut it is supposed to hurt the lea-ther, and make it apt to crack.
BLACK LOCK, Thomas, D. D. was horn in 1720, at Annan,in Dumfries-shiiv, of poor parents. Before he was six years old,he lost his sight by the small-pox, which prevented his father fromexecuting his intention ot bringing him up to some trade. Hetherefore encouraged the inclination he had early [shewn forbooks, by reading, to amuse him, first the small publicationsusually put into the hands of children, and afterwards the worksof our best authors, such as Milton, Prior, Pope, Addison, See.His companions, attached to him by affection, as well as compas-sion,