Page:Encyclopædia Britannica, Ninth Edition, v. 5.djvu/591

Rh UNCLASSIFIED COMPOUNDS.] CHEMISTRY 579 Balsams are natural mixtures of resins with volatile oils. Bitumens result from the decay of vegetable matter out of contact with the air. Pit-coal, lignite, and jet are allied to bitumen. Petroleum and rock-oil have been referred to as paraffins (p. 556). The remaining compounds we have to notice are of animal origin. Albuminoid Substances or Proteids. These substances contain carbon, hydrogen, nitrogen, oxygen, and small quantities of sulphur (0 8 to 1 6 per cent.). Serum of blood is an albuminous substance, soluble in water, precipitated by alcohol, and coagulated by beating. Egg- albumin is the chief constituent of white of egg ; it differs from blood serum in being precipitated by ether. Globulin is present in blood serum, connective tissue, ic.; it is insoluble in water, soluble in dilute acids and alkalies. Myosin, allied to globulin, exists in muscular tissue, and vitellui in yolk of egg. Casein is an alkaline alb animate which occurs in milk, coagulable by certain animal mem branes (such as rennet or stomach of calf), with the forma tion of cheese. Fibrin is the proteid which causes the clotting of blood ; it is an elastic substance of filamentous structure, insoluble in water at ordinary temperatures. Peptones result from the action of gastric juice upon albuminous substances ; they are soluble in water, and are not coagulated by boiling. Hemoglobin (which, with the other substances to be mentioned, is allied to the proteids) is the chief con stituent of the red corpuscles of the blood of vertebrate animals ; it can be obtained in the crystalline form from the blood of certain animals, and contains, in addition to the usual elements composing proteids, about - 4 per cent, of iron. Haemal in results from the decomposition of haemoglobin. Pepsins is the albuminous constituent of gastric juice, which converts proteids into peptones. Mucin (Mucus) is a secretion from the salivary glands, and from all mucous membranes of the animal body. Gelatin and Chondrin. The first of these substances is produced by the action of boiling water on membranous tissue, skin, tendons, and bones. Isinglass is nearly pure gelatin from the swim-bladder of the sturgeon and other fishes. Common size and glue are examples of impure gelatin. Gelatin is soluble in water and precipitated by alcohol ; the aqueous solution is completely precipitated by tannic acid (p. 570), this last reaction being the basis of the process of tanning. When hides are steeped in an infusion of oak-bark or of other substances yielding tannic acid, the gelatine of the hide by the action of the tannin is converted into leather. Chondrin is a gelatin ous substance, obtained from the cartilage of the joints and ribs, which differs in some respects from gelatin. Keratin is a name given to several substances left after the complete exhaustion of horn, nails, feathers, hair, &c., by various solvents. Protagon is a phosphorettei fatty substance, forming the chief constituent of nerve tissue. Boiled with baryta vater, it decomposes into stearic acid, glycerin, phos phoric acid, and other substances, among which is in cluded trimethyl-oxethyl-ammoniuui hydrate or neurine, N(CH 3 ) 3 (C 2 H 4 .HO)HO. (R.ME.) INDEX OF PRINCIPAL SUBJECTS. Acetylene, 521, to 1 ). Acid, hyjiochloric, 492, hydro cyanic or prussic, 5-54: nitric, 510-512 ; sulphuric, 503- 50G. Acids, 477, 485; organic, 553, 563-571: basicity of, 486; heat developed by, 437. Action, chemical, 474-476. Affinity. 463-465. 473 Albuminoid substances, 579. Alehemistical period, 459. Alcohols, 553, 563, 564; sul phur, selenium, and tellu rium alcohols, 553, 566, 567 Aldehydes, 553, 567, 563. Alkalies, metals of the, 524, 525. 543. Alkaline earths, metals of the, 5--&amp;gt;5, 526, 513. Alkaloids, natural, 576. Aluminium, 532, 533. Amides. 5-34, 577, 578. Amines, 553, 554, 574-577 Ammonia, 509, 510. Anhydrides, 533, 571. Aniline. 577

timony, 539-541. Arsenic, 539-511. Arsines, 577. Atomic heat, 470 Atomic weights, list of, 467. determination of. 463-471 ; relations of, 543; of Ber- zelius, 465 Avogadvo and Ampere, hypo thesis of, 465, 468. Barium, 525. 526. Bases, 477, 436. Benzene series of hydrocar bons, 560-562. Bismuth, 533-541. Bismuthines, 577 Bleaching powder, 494. Boron, 520, 532, 533. Boy!e and ifariotte, law of, 468. Bromides, 478. Bromine, 490-494; 496.498 Cadmium, 526-528, 543. Caesium, 524. 525, 527, 544. Calcium. 525, 526. Calcium chloride tube, 545. Carbohydrates (sugar, starch, gum, &amp;lt;fec.), 564. Carbon, 520, 521, determina tion of. 544-546. Carbon disulphide, 521. Cerium, 542, 543. Charles and Gay-Lussac, law of, 463 Chemical affinities, first tables of, 463. Chemistry definition of, 467 ; first definition of 459 Chemistry of the ancients, 459. Chlorides, 473. 514. Chlorine, 490-406, 498, oxy- acids of. 494, 495. Chromium, 533-536 Cobalt, 533-536, 533. Combination by weight and volume, laws of, 467 Combustion furnace, 545, tube, 544. Copper. 523-530. 536. 53S. Crystallization, water of 489 Cyanogen and its compounds, 535, 554, 555. Dalton, atomic theory of, 465, 463. Density of bodies, determina tion of, 4G9 Didymium, 542, 543. Dissociation, 475 Duulistic theory, 466. Dumas s vapour-density appa ratus, 547. Electro-chemistry, 46G. Elements, definition of. 467; dates of discovery of, 464; names and symbols of, 467 ; negative and positive, 476 ; non-metallic, 476; specific heats of, 470 ; valency of, 473. Equivalency, doctrine of, 463. Equivalent of an element, de finition of, 470. Ei hi urn, 542, 543. Ethereal salts or compound ethers, 553, 572. 573. Ethers, 553 ; haloid. 553, 564- 566. sulphur, selenium, and tellurium, 553, 566, 567 Fatty and aromatic groups, 552. Fluorine, 490-194 Formulae, constitution of, 547; empirical, 472, 547, graphic, 473 : 474. 549, 550: mola- cular, 472. 547-549; ra tional, 473. 474, 549. Gallium, 471, 527. Gay-Lussac, laws of, 465. Glucinum, 526-523, 543 Glucosides, 572. Glycerin, 564. Glycols, 564. Gold, 523-530, 536, 533. Hoemoglobin, 579. Hilides. acid, 553, 571. 572 Hiiogens, the, 490-498 ; de termination of. 547. Heat and chemical action, connection of, 474. Historical introduction, 459 Hofmann s vapour-density ap paratus, 548 Homologous series, 551, 552 Hydrides. 476, 514. Hydrocail-ons, 553, 556-562 Hydrogen, 478, 479, 483-490. 543 ; determination, of, 544, 545. Hydrogen dioxide. 4i9, 490. Hydroxides, 435-439, 513. latrochemistry. 460. Indium, 471, 532, 533. Iodides, 473 Iodine, 490-494, 496-493. Indium, 536-533 Iron, 533-536, 543. Isologous series, 552. Isomorphism, law of, 471. Isomerism, physical, 550 ; chemical, 550, 551. Ketones, 553, 568. Lanthanum, 542, 543. Lavoisier, system of, 463. Lead, 530-583. Liquids, combustion of, 545. Lithium, 524, 525, 544. Magnesium, 526-528 Manganese, 533-536, 543. Mercaptans, 567. Mercury, 526-523. Metals, properties of, 476. Metamerism, 551 Molecular weights, 471, 472. Molybdenum. 541, 542 Nickel, 533-536, 533. Niobium, 539-541. Nitrides. 473. Nitrogen, 509-514; acids cf, 510-514; determination of, 546, 547. Notation, chemical, 472 ; equi valent, 465. Olefines. 553, 559 Organic chemistry, 520, 521, 544. Organic compounds, definition and character of. 544. clas sification of, 551, 554, fami lies of, 553 ; ultimate analy sis of. 544-547 Oigano-boron compounds, 574. Organo metallic bodies, 553, 573 Organo-silicon compounds, 523, 524. 574. Osmium, 53(5, 537 Oxides, 477. 473, 544 Oxygen, 479-133; determin ation of, 547. Ozone, 431-433. Palladium, 536-533 Paracelsus, doctrines of, 459. Paraffins, 556-553. Periodic relations of elements, 543 Phenols, 563. Phlogistic theory, 460, 461. Phosphides, 473. Phosphines, 577 Phosphorus, 515-519, 540; acids of, 517-519; determination of, 547. Platinum, 536-583. Polymerism, 551. Potash bulbs, 545. Potassium, 524, 525, 544. Proteids, 579. Radicles. 474, doctrine of com pound, 466 ; organic, 552. Residues of Gerhardt, 466. Rhodium. 536-538. Rubidium, 524, 525, 544 Ruthenium, 536, 537. Salts, 478. 486; acid, normal, and basic, 487 Selenium, 498, 499, 501-503; 506, 503 SiLcon, 521-524. Silver, 528-530, 536. Sodium, 524, 525, 536. 544. Solution, heat developed or absorbed in, 485. Spagyrists, 459. Specific heat, relation of, to atomic weight, 470, 471. Stibmes, 577. Strontiun, 525. 52G. Substitution, doctrine of, 466. Sulphates, 505, 530. Sulphides, 473. Sulphur, 498-509; determin ation of, 547 ; acids of, 499- 507. Tantalum, 539-541. Tellurium, 493, 499, 501-503, 506, 508. Terpenes, 559, 560. Thallium, 530-532. Thorium, 542, 543. Tin, 538, 539, 541. Titanium, 538, 539. Tungsten, 541, 542. Types, theory of, 466, 474. Unclassified organic com pounds, 578, 579. Uranium, 541, 542. Urea, 578. Vanadium, 471, 539, 540. Vapour-density, determination of, 547, 543 Water, 483-485. Yttrium, 542, 513. Zinc, 526-523. Zirconium, 533, 539, 541,