1187

GRAPHITIC ACID.

GREASE.

1188

5

GRAPHITIC ACID, C,,H,O, (C22H4010) [GRAPHITE, E. C. vol. iv. col. 465]. This acid is produced by heating purified graphite with potassic chlorate and nitric acid to 60 for three or four days. It forms transparent thin crystals belonging to the trimetric, or to the monoclinic system. It is somewhat soluble in pure water, but insoluble in dilute acids. It unites with alkalis, and, when heated, decomposes with explosion. (Brodie, Ann. Chem. Pharm. cxiv. 6.)

GRAPHOTYPE is the name given to a new mode of engraving for surface printing. A trifling incident is said to have suggested its introduction. Mr. De Witt C. Hitchcock, a draughtsman and wood-engraver, of New York, having to correct a drawing on boxwood, and having none of the ordinary white pigment at hand, made use of the enamel of a visiting-card; and he noticed that after he had removed the enamel by a wet brush, the ink-lines stood up in relief upon the card. This suggested to him a mode of engraving by drawing with some kind of ink on a chalky surface, and, brushing away the chalk from between the ink lines, leaving a surface fitted to be printed by the letter-press method. The result of many experiments led to the substitution of French white for ordinary chalk; and to the printing from a stereotype or electrotype, rather than from the block itself. Mr. Fitzcook worked up the subject into a practical form for commercial application, and described the processes before the Society of Arts in 1866.

The preparation of the block requires much care. The best French chalk is finely pulverized and sifted on a zinc plate, the size of the intended picture; a polished steel plate is laid on the powder, and a heavy hydraulic pressure brought to bear, by which the chalk-powder is consolidated into a firm compact mass with a beautifully smooth surface. The zinc and the chalk together are about equal in thickness to an ordinary stereotype plate. The ink is made chiefly of glue and lampblack. The design is drawn on the smooth chalk surface, after the latter has been sized and dried, by means of a fine camel- or sable-hair pencil. The ink soon dries, and then the chalk untouched by the pencil can be rubbed away from between the ink lines by brushes of various degrees of stiffness, leaving the ink-lines of the design as in a wood-block, standing up in sharp relief. The block or plate thus prepared is steeped in a solution of water-glass, the silicate of which hardens the chalk. A stereotype or electrotype is obtained in the ordinary way from the block, to be printed from.

The graphotype process has the great advantage of enabling the designer to become his own engraver; and hence it was at first believed and hoped that it would afford an artist of original power a ready means of bringing his ideas before the public. But the mechanical difficulties in the way of refined artistic work have been found to be so great as to seem almost insurmountable. Whilst the process presents the primary qualification of enabling the designer to etch his drawing, as it were, without the tedious and uncertain process of etching, it has been found, so far, that the brilliancy, variety, depth, and delicacy which can be obtained by a skilful use of the etching-needle are quite unattainable by graphotype. Of course the process may be susceptible of improvement; but, hitherto, for the higher grades of art-work it has failed. For many kinds of mechanical design it appears, however, to be fully available, and it is being carried out on a tolerably large scale as a commercial undertaking by the Graphotype Company, Limited, who have published a Hand-book of Graphotype,' containing numerous illustrations of the process, and directions for the guidance of artists and amateurs. To be really successful it will be necessary that competent artists should devote themselves to the special study of the process, and to the development of a style of design and manner of manipulation especially adapted to its limits and capabilities.

GRASS, CHINA [CHINA GRASS, E. C. S. col. 523]. GRASS CLOTH is a name sometimes given to a fine and delicate kind of muslin prepared by the natives of India, either from China grass or some analogous material. But it is believed that all true grasses yield filaments too coarse for this purpose; and that the real Indian grass cloth must be prepared from some other kind of fibres, the varieties of which in that country are So numerous. One delicate textile fabric, the pina muslin, is made from the fibres of the Bromelia pigna.

GRASS-OIL, Grass-Oil of Namur, a volatile and aromatic oil obtained from the Calamus aromaticus, and sometimes incor

GRASS, SPANISH [ESPARTO, E. C. S. col. 905]. GRASS WRACK, or Zostera Marina, a plant growing at the bottom of sea and salt-water ditches, is applied to many purposes in the arts-as a covering for Italian liquor flasks; a packing material in boxes and cases containing bottles and glass; and as a stuffing for pillows and mattresses in some of the northern countries of Europe.

GRATE [COOKING APPARATUS, E. C. vol. iii. col. 181; FURNACE, E. C. vol. iv. col. 239; SMOKE; SMOKE PREVENTION, E. C. vol. vii. col. 627; WARMING AND VENTILATION, E. C. vol. viii. col. 707]. GRAVE-YARDS, AIR OF [HYGIÈNE, E. C. S.].

GRAVEL, the amorphous or crystalline sediments lodged in the bladder or voided with the urine. The amorphous forms consist chiefly of lithate of animonia (red, pink, or lateritious), or of mixed lithic and phosphatic sediments (white); the crystalline forms of uric (lithic acid) known as red gravel, or of the triple phosphate of magnesia and ammonia, known as white gravel.

GRAY DYES AND PIGMENTS. These can scarcely be regarded as distinct colours, seeing that gray is only an intermediate shade between black and white, combining the two in any one of many proportions. Still, as the name gray is often given to tints which have a little yellow or blue in them, dyers and colour-makers devise experiments on the best modes of producing them. There are always two or three dyeings to give a gray colour to textile goods. To give an ash-gray to woollens, the cloth is boiled in a solution of gall-nuts and winestone (crude tartar which settles on the sides and bottoms of wine casks): water and sulphate of iron are added to the solution, and the dyeing is finished by a second immersion of the cloth. In dyeing wool gray before weaving, one mode is to boil the wool in a solution of tartar; gall-nuts, sumach, sulphate of iron, and more water, are added, and the wool boiled a second time; copperas is added to the bath, and the gray tint finally given to the wool by a third boiling. Many other recipes are adopted, according as the textile material operated on is cotton, wool, silk, or flax. To produce a yellowish gray, alum is used instead of tartar, fustic instead of nut-galls, and a mixture of sulphate of iron and sulphate of copper instead of copperas. Another method consists in boiling the cloth or yarn in a solution of fustic; then in a solution of nut-galls and alum; and then in the same bath with an addition of vitriol and decoction of logwood. Many other varieties of gray, known by the names of pearl-gray, mottle-gray, tawny-gray, iron-gray, slate-gray, &c., are similarly produced by three boilings or dyeings; acetate of iron, weld, or indigo being substituted for some of the ingredients above named.

GREASE, for the axles of wheel carriages, has become an important substance since the introduction of railway travelling, owing to the necessity for providing a good lubricant for vehicles running at high speed.

Grease suitable for ordinary carts and waggons is made chiefly of caustic lime and resin-oil, with or without a little water. If the wheels have no axle-boxes, the grease is made of such consistency as to be easily spread on the bare axle. The oil is obtained by the distillation of resin; but when this substance is dear in the market, some cheaper substitute is employed, such as refuse-paraffin, candle-making residues, fish oil, or pitch oil; but none of these are so good as resin oil. In practice, numerous combinations of ingredients are employed, for many of which patents have been obtained.

Grease of medium quality will suffice for low-speed railway service; but for high speed, and especially for locomotives, the choice of materials and the processes of manufacture require much care. Some kind of oil or tallow is the basis, with a little soda-crystal to give consistency and durability. Palm oil is used, with or without tallow; if oil only, it amounts to 45 per cent. of the whole weight; if oil and tallow, the two together only 35 per cent. Experiments have shown that, with palm oil alone in the grease, the axle-boxes supplied with a definite quantity become exhausted in a much smaller number of miles run than when tallow is added; that the proportions should vary according to the speed to be maintained; and that grease for summer use should be harder than that intended for cold weather. The following recipe is for 1 ton of locomotive grease, to run 1,000 to 1,200 miles in cold weather :-3 cwt. 84 lbs. tallow, 2 cwt. 56 lbs. palm oil, 35 lbs. sperm oil, 1 cwt. 14 lbs. soda crystals, 12 cwt. 96 lbs. water. If for warm weather, 4 cwt.

56 lbs. tallow, 2 cwt. 56 lbs. palm oil, 27 lbs. sperm oil, 1 cwt. lbs. soda crystals, 12 cwt. 26 lbs. water. In combining these ingredients to form the unctuous yellow substance with which most passengers by railway are familiar, the oils and tallow are melted at about 180° F.; the soda crystals are dissolved in the water in another vessel at 200° F.; and the two are mixed together so as to be as intimately incorporated as possible, with the exclusion of all dust and impurities. Several tests are applied to the quality of railway grease-it should be of a consistency to suit the season of the year; little subject to increase of temperature even at high speed; leave no residue in the axlebox; not be so stiff as to heat the axle; and not so soft as to be exhausted in a few miles' running. When just fitted for its purpose, it becomes in working a kind of thick cream, which flows up and down in the axle-box. Cart-grease is made largely in the Tyne district, in connection with manufactures which leave resin as a cheap residue. Some makers devote their chief attention to railway grease; but the great companies mostly make their own, in order to introduce such improvements as experience may from time to time show to be desirable.

GREEK-FIRE, a compound much used in ancient warfare, and supposed to have consisted mainly of naphtha. It is said to have been a mixture of asphalt, nitre, and sulphur.

GREEK LANGUAGE AND LITERATURE. [GREECE, ANCIENT, E. C., Geog. Div., vol. iii. col. 85; ÆOLIANS, ibid. vol. i. col. 74; DORIS, DORIANS, ib. vol. ii. col. 177; IONIA, ib. vol. iii. col. 285; and the principal writers under their several names in the Biog. Div.]

GREEN DYES AND PIGMENTS. Any tint of blue, combined with any tint of yellow, will produce green; and this easy mode of production is much adopted in the practical arts. There are, however, green colours possessed or yielded naturally by many substances; and as some of these are more beautiful than any mixture of blue and yellow, it is an object of importance to increase their number.

Copper is the chief source of mineral green. Mountain green consists of the oxide, hydrate, or carbonate of copper, variously prepared; it is sometimes called green bice; but the best kind is malachite, ground up with orpiment. Emerald green and Scheele's green are arsenite of copper, obtained by the action of arsenious acid and potash on sulphate of copper. Brunswick green and Bremen green are obtained from carbonate of copper, chalk, and ammonia; one variety from sulphate of copper, alum, and ammonia. Friesland green is obtained by the action of sal ammoniac on sulphate of copper. Schweinfurth green, obtained by the action of arsenious acid on acetate of copper, is a beautiful colour, much in request for wall papers and artificial flowers, and used for colouring sweetmeats; but its poisonous qualities render it dangerous. Verdigris is in substance an acetate of copper. A fine green used by enamellers is sesqui-oxide of chromium. Of the green mineral colours produced by the mixture of blue and yellow, the chief kinds are :-Chrome green, made from chrome yellow and Prussian blue; Barth's green, Prussian blue and yellow lake, with a little clay; Gellert's green, cobalt blue, chrome yellow, and flowers of zinc; Prussian green, Prussian blue and gamboge. Brighton green, and many other kinds, are merely names for compositions slightly differing from the above.

Of greens of vegetable origin, the chief is sap-green, obtained from buckthorn berries. The berries are fermented for several days, then pressed, and alum added to the juice; the juice, when concentrated by slow evaporation, is put into pigs' bladders, where it dries and hardens. Greens of somewhat similar kind are obtained from black alder and privet. The Chinese have a rare and costly green indigo, called luh-kao.

Magnificent green colours are now obtained among the coaltar series. [ANILINE DYES AND COLOURS, E. C. S. col. 131.] In painting and enamelling, the green colour, selected from any of the above, is usually produced or rather laid on at once; but, in dyeing, it is more customary to have two operations, a blue dye succeeded by one of yellow. The dye can in this way be better adapted to the quality of the yarn or textile goods. GREEN SICKNESS. [CHLOROSIS, E. C. S., col. 538.] GREGORIAN CHANT. [CHANT, E. C. S. col. 489.] GRENADIN. [GRANATIN, E. C. S. col. 1180.] GRIFFIN. The griffin and the ideas it symbolises are very ancient, forming a component of some of the oldest mythologies of the world. The Assyrians, Chinese, Greek and Roman legends alike mention this fabulous creature, which was composed of the head, forepart, and legs of an eagle, united with the

hinder half of a lion. In latter heraldic usage in which this charge is frequently employed both by French and English blazon, and in a shape but slightly varying from that depicted upon ancient vases and carvings, it is generally represented segreant, a special term of heraldry signifying the same as the term rampant, which is applied to wild animals; its tail is usually reflected over its back. The origin of the union of two so different creatures is uncertain, but must, in all probability, be referred to the same source as the imagination of the minotaur, the chimæra, the centaurs, Pan, the fauns and satyrs, and the many kindred shapes, dualistic or heteromorphic, which stud the realms of old-world mythology. The greed for novelty was, no doubt, the moving spring which actuated the ancients in the first instance to conceive the notion of hybrids between creatures of widely different organization, and, finally, to put the idea to the test in cases of any practicability; and although the results fell very far short of their expectations, they were none the less prevented from exercising their imagination in its widest flights, and conjuring up at will the strangest combinations of animal creation. Hence the mythological legends of Pan, Leda, Pasiphaë, and Io, are merely representatives of current and widely spread deductions from a chain of facts gathered from natural and observed sources, which found its echo in the anthropomorphic zoocephalic deities of Egypt as fitly as in the many-handed gods of India, the wings of angels, the weird forms of beasts in the visions of Daniel and St. John the Divine, and gradually faded away in the heraldic wyvern, the cockatrice, and the catamount of a few hundred years ago. That hybrids may be produced by creatures occupying more or less allied positions in the natural order of creation is well known, but the possibility of keeping up a self-producing race of such creatures, even from original forms most closely connected, is still, perhaps, an open question, but must probably be decided in the negative. [HYBRID, E. C. Nat. Hist. Div. vol. iii. col. 149.]

GRIFFITH'S MIXTURE, a medicine containing sulphate of iron as its most active ingredient, and largely administered in cases of anæmia. It is the mistura ferri composita, or compound mixture of iron, of the British Pharmacopoeia.

GRINDERS' ROT, a severe and dangerous affection of the lungs produced by the mechanical irritation of the particles of steel and stone given off in the several grinding operations of workers in steel at Sheffield and elsewhere. [HYGIÈNE, E. C. S.] GRINDING, SAND-JET, is a remarkable process in which grinding or abrasion is effected by the percussion of small hard particles on a plain surface. It has long been known that the glass of windows near the sea-side, exposed to the action of wind-driven sharp sand, becomes roughened or dimmed; and a close examination will show that the surface has received innumerable minute indentations or scratchings, by the impact of small hard particles against it. Mr. Tilghman, of Philadelphia, has ingeniously applied this fact to practical purposes; the subject was brought before the notice of the Franklin Institute by Dr. Wahl in 1871, and an account of it inserted in the Journal of the Institute.

Mr. Tilghman employs sharp silicious sand, varying in hardness and fineness according to the kind of work to be done. This sand is impelled by a blast artificially produced, of steam in some cases, of air in others. Some of the results obtained are remarkable. A hole, 14 inches diameter by 1 inches deep, has been bored completely through a solid piece of corundum (one of the hardest minerals known, next to the diamond) in twentyfive minutes, by sand driven with steam power at 300 lb. pressure on the square inch. With a pressure of 125 lb. on the square inch, produced by a steam engine of 14 horse-power, a hole has been cut 1 inch deep into granite in one minute, 3 inches into marble, and 10 inches into soft brown sandstone. A diamond has been sensibly reduced in weight, and a topaz altogether dissipated, by a sand-jet in one minute. A hole one inch long by

inch wide, has been completely bored through a hard steel file 4 inch thick in ten minutes, with a steam-jet of 100 lb. pressure on the square inch. With 50 lb. pressure, a hole has been bored through a piece of hard granite by small lead shot, the shot themselves being only slightly flattened by the con

cussion.

These results are brought about by causing a sand-stream to mix with a steam-jet. The sand passes through a central airtube, and steam through an annular tube which surrounds it; a kind of suction acts at the end of the concentric tubes, which draws the sand into the steam-jet, and both are dashed with great force against the stone or other substance to be acted upon, which is placed about an inch away from the end of the tube.

The stone is considerably heated by the violence of the impact. The cutting effect is most considerable when there is free escape for the sand, steam, and abraded particles of stone; if the hole bored is not much larger than the diameter of the jet, these impediments retard the process. By the use of flexible jointed connecting tubes, the jet can be turned in any direction; hence grooves, mouldings, letters, figures, ornaments, &c., can be produced, instead of merely straight cuts or cavities.

A more remarkable surface effect, partaking somewhat of the nature of engraving, is produced by using an air-jet instead of a steam-jet, and varying the velocity or pressure. Glass can be de-polished, or rendered like crown glass, in less than one minute. By covering parts of the glass with a stencil or pattern, made of paper, lace, india-rubber, or oil-paint, a design may be engraved. If the blast or jet has a small velocity, delicate substances, such as green fern leaves, will resist the stream of fine sand long enough to engrave their outline on the glass. By graduating the time of exposure, much of the effect of light and shade may be produced. It may seem strange that the particles of sand will cut hard stone, glass, or steel, but not soft substances; this is due to the fact that each particle makes a minute cavity at once by direct impact, when the receiving surface is hard; whereas a softer substance acts as a buffer or elastic rebounding cushion. When fine wire-gauze is placed flat and evenly on a piece of glass, the latter may be cut entirely through: producing a kind of sieve with open meshes or holes inch in diameter, separated by threads or lines of glass inch wide. This curious result cannot be obtained by any other known means than the sand-jet. Instead of actual perforations, the glass may be made to present polished lines on a ground surface, by placing a piece of fine lace upon it, and then acting with the sand-jet. Glass copies of engraved prints may be obtained; a photographic negative of the engraving is taken on glass coated with bichromatised gelatine; a jet of very fine sand, propelled by a moderate blast, will eat away the surface of the glass proportionately to the thickness of the gelatine in different parts; and thus the picture is reproduced in a kind of semi-ground or unequally ground glass. The material called "flashed" glass, consisting of a thin film of coloured or stained glass on a thicker white or transparent substratum, may be engraved in a beautiful manner, by laying any kind of gauze, lace, or open pattern on it, bringing the sand-jet into play, and allowing it to act just long enough to cut through the coloured portion: thus producing a delicate coloured glass pattern on a colourless glass ground. In the mechanical arts, the surface action of the sand-jet has been used to clean the interior of cast-iron hollow-ware vessels before tinning them; a thin film is blown off by the sand, instead of turned at the lathe, producing a clean fresh surface. The President of the Franklin Institute, when presenting the Institute medal to Mr. Tilghman in 1872, stated that glass ornamented by the sand-jet process is equal to that etched by powerful acid; superior in regard to the absence of all undercutting; and that some of the effects could not be produced by any other known method.

In the engraving or surface process, a rotary fan sends a blast of air down a vertical tube; sand is fed in at the top of the tube, and is dashed by the blast against the glass or other surface, which is moved slowly forward under the lower end of the tube. The spent sand is conveyed upwards, and used again and again. Whether the processes be cutting, boring, drilling, grinding, depolishing, or engraving, they are one in principle-grinding by concussion.

driven out to the circumference by centrifugal force, and is beaten to powder by the bars as it goes, the bars or beaters of one disc revolving in an opposite direction from those of the other. The apparatus is intended for grinding corn, cleansing grain and seeds from incrusted dirt, cracking mast or beech nuts, and pulverizing minerals. GRINDSTONES. The best kind of grindstones employed as millstones for grinding corn into flour are made of a species of silex called buhr-stone, which occurs in large masses, sometimes in continuous beds, in other instances isolated, amid deposits of sand and marl. The best deposits of this stone occur in the Paris basin. The specimens best fitted for corn-grinding have about an equal proportion of solid matter and vacant space, so remarkably is the substance honeycombed with cells. The finest quarry is upon high ground near La Ferté sous Jouarre, in the open air. The stone is cut out in masses from one to two yards in diameter, by a series of iron and wooden wedges, gradually inserted in the clefts which they form. The masses are afterwards cut into cubical and other shaped pieces, which are bound with iron hoops, and dressed up into millstones. A coarse conglomerate sandstone is sometimes used as a cheap substitute for the buhr-stone, but with inferior results. A larger supply of millstones, somewhat less perfect in texture, has been obtained for many centuries from Nieder Mendig, near Andernach, in Rhenish Prussia. The stones are fashioned into millstones by hammers and chisels; the furrows on the surface, which increase the grinding action of the stone, are produced by means of a heavy double-edged hammer. The grindstones used in vast numbers by the Sheffield cutlers are mostly made of a peculiar kind of stone found at Eckersley and at Gateshead Fell.

Mr. Ransome's artificial stone, employed for various processes in the arts, is being tried as a material for grindstones or millstones. The substance consists of sand, gravel, pebbles, fragments of limestone or granite, or some other cheap stony material, ground up very fine, sifted, and mixed into a paste with a liquid prepared by dissolving flint in a solution of caustic soda, under pressure, and at a high temperature. The paste, when mixed, is poured into boxes or moulds of any desired shape, dried slowly, and steeped in a solution of chloride of calcium. The chemical change, brought about by the combination of the soda with the chlorine, and the expulsion of this compound as a liquid, leaves the calcium to combine with the siliceous particles into a hard, solid substance; or, rather, fragments of real stone become cemented together by a kind of silicate of lime, forming a sort of flint-glue, hard, strong, impervious to moisture, and capable of resisting atmospheric changes. By selecting and proportioning the ingredients, various degrees of fineness may be obtained. Sharp, clean, dry sand is the siliceous ingredient best suited for grindstones. The paste is pressed uniformly into the moulding-box; the substance comes out free from flaws, and the stones can be made of any size and any degree of hardness.

GRIPPE, a French term for epidemic catarrh or influenza. GROATS, the grains of the oat (Avena sativa) deprived of their husk.

GROCERS' ITCH, a disease of the skin, known as Eczema impetiginodes, caused by handling sugar and treacle. GROIN. [ARCH, E. C. S. col. 143; VAULT, VAULTING, E. C. vol. viii. col. 573.]

gryllus of the form first mentioned; the legend is broken away, or too indistinct to be deciphered. Side by side in point of date with these seals, which have impressions of ancient gems, occur impressions of seals which are entirely metallic, and bear devices copied from the grylli of the gems. The seal of Thomas de Camera, of Norfolk, in the thirteenth century, for example, appended to a charter in the Harleian collection, 47. H. 52, exhibits a fine example of the gryllus (fig. 6). The human face and horse's head are combined with the hinder half of a lion rampant, the entire monster being enclosed within a lozenge and a square interlaced; the separate letters of the legend, PRIVE SU, a common motto of medieval seals, being placed in the intervening spaces. This type exists in a seal of parallel design, that of Johannes Cook, of Barnolby, appended to the Harleian charter, 112. G. 60, but the execution is later and coarser; the date is 1393, and the legend an extended form of the above motto, PRIVE SU E POI CONU, for "Privé suis et peu connu." The gradual degeneration of the gryllus of many devices into a

GUAIARETIC ACID, C20H2604 (2H,CH2406). Guaiacum consists chiefly of this acid, which is extracted by boiling the pulverised resin with milk of lime, exhausting the insoluble residue with hot alcohol, and evaporating. The impure acid thus obtained is converted into a sodic salt, recrystallized, and the acid reprecipitated by hydrochloric acid: a final crystallization from strong acetic acid renders it pure. It forms colourless, inodorous needles, which melt at 80°, and yield crystalline salts with metals. It dissolves in alcohol, ether, and dilute solution of potassic hydrate, but not in ammonia. Its alcoholic solution turns the plane of polarization to the left, and gives a bright green colouration with ferric chloride. (Hlasiwetz and Gilm. Ann. Chem. Pharm. cxix. 266.) GUAJOL. [GUAIACENE, E. C. S.]

simple animal form with human head is seen in (fig. 7), an oval seal of the thirteenth century, with the legend CREDE FERENTI "Trust the bearer;" and in another (fig. 8), with the legend S' LARANCII DE VARLIACO CL'I-"The seal of Laurence de Varliaco, clerk," a foreign seal of late execution; and in (fig. 9)| a bird-like combination of a snake, a wyvern, and a grotesque head, with the legend, S' BERARDI FILII UGONIS-"The seal of Berard Fitzhugh." The seal of Roger, son of Adam Judas de Turpleton, in 1341, appended to the Harleian charter, 112. A. 40, has a small bird-shaped figure with human and animal heads, and the motto, JE SU SEL NUVEL-"Je suis sceau nouvelle"; that of Thomas, the son of Sir Nicholas de Falesham, in 1283, a bird with human head and tail composed of an animal's head, with legend, Bou (Harl. ch. 83. E. 34). The human-faced squirrel, with the motto, VEITCI MERVAYLE, for "Voici merveille," appears on the seals of Roger de Reymes, or Thomas de Reydon, in 1316 (Harl. ch. 55, C. 46), and of John Fairsyde, chaplain, in 1414 (Harl. ch. 112. A. 15). A similar example occurs with the legend CREDE FERENTI. Another type is that of four faces in profile, commixed with hares or rabbits, and a bird-like form with human head, and the legend, PRIVE SU POY CONU, a variation of one of the above forms.

GUAIACENE, CHO (CHO), Gaiacene, guajol, an oil boiling at 118°, obtained in the dry distillation of guaiac resin. When exposed to the air it becomes oxidized and converted into a substance crystallizing in laminæ. (Deville, Compt. Rend. xvii. 1143, xix. 134; Gilm. Ann. Chem. Pharm. cvi. 379.)

GUANIDINE, Carbotriamine, Cyandiamine, CH,N1 = C(NH)"(NH2)2 (C2H,N,). This base was discovered by Strecker, and is formed by the action of hypochlorous acid on guanine, and by heating biuret, C,H,N,O, (CH ̧NO), to 170° in a current of hydrochloric acid gas. It may also be obtained by heating an alcoholic solution of cyanamide with ammonic chloride, or better by the action of alcoholic ammonia on iodide of cyanogen. One of the most convenient methods of preparation, however, is to heat chloropicrin to 100° with an alcoholic solution of ammonia for several hours, evaporate the product to dryness, and exhaust the residue with absolute alcohol, which dissolves the guanidine hydrochloride and leaves the ammonic chloride. By treating the solution of guanidine hydrochloride with argentic oxide, the hydrochloric acid is removed, leaving the guanidine in solution. The latter, when evaporated in vacuo, yields the guanidine as a crystalline, strongly alkaline mass, having a caustic taste, and absorbing carbonic anhydride readily when exposed to the atmosphere. It unites with acids to form crystalline salts; the nitrate crystallizes in sparingly soluble lamina.

GUAIACOL, Hydride of guaiacyl, guaiacylous acid, pyroguaiacic acid, C,H ̧O2 (CHO). This substance, which has the composition of methyl-pyrocatechin, CH,MeoHo, occurs in beechwood tar along with creosol and various derivatives of phenol. It is a colourless oil boiling at 200°, and when heated with hydriodic acid yields methylic iodide and pyrocatechin. Conversely, when pyrocatechin is heated with potassic hydrate and methylsulphate, guaicol is formed. (Marasse, Ann. Chem. Pharm. clii. 80; Gorup-Besanez, Zeits. Chem. [2] iv. 392.)

GUAIACONIC ACID, CH22O3 (C3H2206), the name given by Hadelich ('Jour. pr. Chem.' cxxxvii. 321) to an uncrystallizable resinous acid remaining in the mother liquors from the preparation of guaiaretic acid.

17

C,H,,N1 =

Triethylguanidine, or carbotriethyltriamine, NCEt,H (CH,,N), unknown in the free state, but obtained as a hydrate by treating sodic ethylate with ethylic isocyanurate. The hydrate is a basic oil which neutralizes acids and forms definite salts with them.

19

=

Triphenylguanidine or carbotriphenyltriamine, C,,H,,N, NCPh,H, (C38H17N3), first obtained by Hofmann by the action of aniline on carbonic tetrachloride. It is most conveniently prepared by the action of heat on sulphocarbanilide. It crys tallizes in needles, which are nearly insoluble in water, but readily soluble in alcohol, especially when heated. It melts at 143°, but is not volatile without decomposition.

A carbotritolyltriamine, C22H23N2 = N ̧CT03H, (CH23N3), has also been prepared. It crystallizes in long silky needles. (Hofmann, Zeits. Chem. [2] ii. 1073, and iv. 721; Proc. Roy. Soc. ix. 284, and xi. 282; Erlenmeyer, Zeits. Chem. [2] vii. 28; Strecker, Ann. Chem. Pharm. cxviii. 151; Finckh, do. cxxiv. 335; Bannow, Deut. Chem. Ges. ber. iv. 161; Merz and Weith, Zeits. Chem. [2] iv. 513, 609; v. 583, 659.)

GUANINE, C2H ̧Ñ2O (C12H2N,O,), an organic base found in the various kinds of guano, but most abundantly in the Peruvian. When pure, it is a white amorphous powder, insoluble in water, alcohol, and ether, but soluble in the stronger acids; the compounds thus produced are very unstable, being decomposed by water. Guanine also unites with alkalis and other metallic oxides. It is converted into xanthine by the action of nitrous acid.

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Nitroguanine, CH1(NO2)N ̧O (C, H1(NO)N ̧O). The nitrate of this base is prepared by dissolving guanine in boiling nitric acid of specific gravity 1.20, and allowing the solution to cool.

Oxyguanine, CH14NSO,? (C20H1N018). Potassic permanganate is added to a solution of guanine in caustic soda until the liquid assumes a reddish-yellow colour; hydrochloric acid now causes the formation of an amorphous reddish-white precipitate of oxyguanine. It is inodorous and tasteless, insoluble in water, alcohol, or ether, but readily soluble in alkaline solutions. (Neubauer and Kerner, Ann. Chem. Pharm. ci. 318; Strecker, do. cviii. 141, cxviii. 151; Kerner, do. ciii. 249.)

GUARANTIE is a contract by which the guarantor, for a consideration, engages to a third person for the debt, default, or miscarriage of another. That other for whose debt or default the guarantie is given is the principal, whose liability takes precedence. The guarantor, therefore, assumes the responsibility of a surety; and the contract of guarantie is collateral to that on which the principal is answerable.

It is often a very nice question whether what appears from the language and circumstances of the transaction to be a gua