Page images
[ocr errors]


mens nearly a foot long, having at least six inches surrounded with bloom. I have not heard of a white variety. The mosses were well represented ; on the moors, by the common club moss (Lycopodium clavatum), called there, “stag's horn moss," and the Alpine club moss (L. alpinum); and on rocks, boulders, &c. by Dicranum scoparium and D. Bonjeanni. The peat-bogs and water-holes were full of innumerable water-plants and mosses, most of them unknown to me, forming a carpet of wonderful beauty in pattern and colouring, such a one as only Nature's pencil could design or her brush enliven with its lovely shades of yellow, green, pink, and purple; truly an enticing seat, but to say the least of it, “just a wee saft.” I recognised here the following species of Sphagnum, S. cymbifolium, S. rigidum, S. Austini, and several other specimens I was unable to identify. Parnassus grass (Parnassia palustris), the two cotton grasses (Eriophorum vaginatum and E. polystachum) and the fragrant sweet gale (Myrica gale) were abundant, greatly adding to the beauty and attractiveness of the spot. In dryer situations, cranberries (Oxycoccus palustris) and crowberries or crakeberries (Empetrum nigrum) grew abundantly amidst the heather, the latter in black shining clusters of five or six, or singly along the small-leaved stems, and were quite as conspicuous as their larger-leaved neighbours, indeed, growing as most of these do right down under the leaves, it is no wonder they so rarely ripen, the average colour being scarlet above and white below, even when ripe they are dry and tasteless, a contrast to the very juicy and not unpleasantly flavoured crowberries; both, however, are very inferior to the purple bilberry or blayberry (Vaccinium myrtillus) also called blowberry, so plentiful in woods. From a distance perhaps, a Scotch moor does not appear a very promising field for the botanist, but on coming to close quarters, the great wealth and variety of vegetable life is truly astonishing, and I feel sure anyone spending even a few hours in studying these moorland wonders, will be amply repaid for so doing.-D. H. S. Stewart.

A WHITE TOAD.-We are accustomed to keep one or two toads in the greenhouse, for the purpose of keeping off injurious insects. One of these animals was put in about four months ago, and has turned a light yellowish white. The temperature of the house ranges from about 50° to 70° Fahr. Is it the heat that has brought about this curious change?-W. H. Seyfang:

BATS FLYING IN SUNLIGHT.-On April 15th,, 1891, I was very much surprised to see a small bat flying about in full daylight. I watched it for some time, and on April 18th I and a friend of mine went to the same field and saw two bats. The sun was shining brightly on both mornings, and both times it was after II A.M. The two were busy when we left, at nearly 1 P.M.-D. M. Higgins, 93 Wellington Street, Luton.

BATS IN DAYLIGHT.-In answer to Mr. J. E. Taylor's note about bats flying in broad daylight, I find the following note in my journal. "I witnessed a curious sight on Sunday, February 15th (1891), the day being bright but cold, on coming out of church just before one, a pair of bats (? species) flying about as if it had been twilight, although as a matter of fact the sun was shining brightly." This was at Harlington, Middlesex.-H. 3. Torpey.

SOCIETY FOR TIIE S.F. DISTRICT.-Would any gentlemen residing in the S.E. district, who are willing to join a small society for mutual and practical study, and field-work send their names and addresses to Mr. L. O. Grocock, 13 Lower Maryon Road, Charlton, S.E. The subscription would be small, and workers in all branches of Natural History would be welcomed.

VARIATIONS OF COLOUR IN PLANTS.—Among the plants liable to variations of colour I have seen no mention of Bartzia odontites, white specimens of which are frequent by the roadside at South Weald and Navestock in Essex. The soil is a stiff clay.Norris F. Davey, Abergavenny.

SWALLOWS DESTROYING THEIR YOUNG.–The philosopher Kant one day was passing a certain building in his daily walk, and on looking up, he discovered as he fancied that the old birds were actually throwing their young ones out of the nests. It was a season remarkable for the scarcity of insecis, and the birds were apparently sacrificing some of their progeny to save the rest.-M, A.

BATS IN DAYLIGHT.-On the 27th April I saw a large bat flying over the river Medway between 12 o'clock and I P.M., a warm, but not very bright day. A few days before a little bat was seen by several people fying near the edge of a wood down in the Weald, at midday. Can it be scarcity of insects that brings the bats out at unusual hours ?-M. E. Pope.

EARLY APPEARANCE THE CUCK00,-The cuckoo was heard on the Barmouth Hills on the 28th of March. Some people say they heard him in the same direction a week before that date.-M. E. T., Barmouth, N. Wales.

The Two SIDES OF THE MEDAL.-It seems to me that a great deal of what Mrs. Bodington remarked on this subject is difficult to controvert. Everybody knows that certain diseases acquired during the life




THE NORTH-WEST OF ENGLAND BOULDER COMMITTEE.—A society under this title has been formed for the study of the glacial phenomena of the NorthWest of England, North Wales, and the Isle of Man. It has been in existence only two months, but already numbers fifty-two members, amongst whom may be reckoned some of the best-known glacial geologists of the North of England. The society is about to publish shortly a handbook for the guidance of its members in the methods of observing glacial phenomena. Meetings are held once a month, and the society is peripatetic, like the British Association.

above receipt is calculated for a full grown person, but must be given to children in smaller quan. tities in proportion to their ages. This medicine has been given to hundreds with success and Sir George Cobb himself has cured two persons who had ye symptoms of madness upon them. If in the madness they cannot take in liquid, make it up into a bolus with honey: after the two first doses, let it be repeated every three or four hours till ye patient be recovered. This repetition to be omitted unless necessary. Take all imaginary care that the musk be genuine." This

bears date 1760.-Thos. Winder, A.M.I.C.E., Sheffield.



time of the parent are hereditary in the offspring, and hence the jealous care exercised by families and the state to prevent the diseases in question, being communicated to the healthy. J. W. Baylis, says the whole question hinges on whether these diseases be acquired or congenital. There are many diseases peculiar to man that must, at all events, have been acquired during the lifetime of the race. Not to talk of diseases the result of immorality, there must have been a time when neither drunkenness nor suicide were manifest. I believe the earlist tendency to a hereditary love of alcoholic spirits arose from our first ancestors who began to indulge too freely, and not from the temperate and moderate. In saying this I know the avidity with which savages take to our intoxicants. Most of these savages have, however, some stimulant or narcotic of their own, less potent than ours, which is therefore preferred. Indeed the building up of that degree of temperance and wisdom, with regard to the use of stimulants, must have been a process that has risen since distillation and fermentation were invented. No doubt it would be acquired somewhat in the lifetime of a parent, and heredity would strengthen it. There are families whose genealogies show us a procession of sober individuals, just as there are others who present us with a long succession of topers. In the same way we might ask concerning every contagious or infectious disease peculiar to man, or to circumstances interwoven with civilisation, Who took it first? Was it not acquired first of all in the lifetime of some individual ? If so, nen, being hereditary, it seems a fair case for those who believe in use-inheritance.7. Shaw, Tynron, Dumfriesshire.

To CORRESPONDENTS AND EXCHANGERS.--As we now publish Science-Gossip earlier than formerly, we cannot undertake to insert in the following number any communications which reach us later than the 8th of the previous month.

To ANONYMOUS QUERISTS.-We must adhere to our rule of not noticing queries which do not bear the writers' names.

To DEALERS AND OTHERS.-We are always glad to treat dealers in natural history objects on the same fair and general ground as amatours, in so far as the "exchanges" offered are fair exchanges. But it is evident that, when their offers are simply DISGUISED ADVERTISEMents, for the purpose of evading the cost of advertising, an advantage is taken of our gratuitous insertion of “exchanges," which cannot be tolerated.

We request that all exchanges may be signed with name (or initials) and full address at the end.

Special Note.—There is a tendency on the part of some exchangers to send more than one per month. We only allow this in the case of writers of papers.

To our Recent EXCHANGERS.-We are willing and helpful to our genuine naturalists, but we cannot further allow dis. guised Exchanges like those which frequently come to us to appear unless as advertisements.

TROUT.— The following extract is from this season's price list of the Howietoun Fishery, Sterling :-“The Rainbow trout in the second generation, have proved much more satisfactory than was anticipated (from noting the imported ova). Where a depth of water of eight feet or over can be obtained, and where the fish can be confined, we now recommend them as the quickest growers and the most beautiful salmonoid we have yet met with. But they must have deep water."

I recently had the pleasure of turning about 2200 Loch Leven (S. Levenensis) yearling trout into reservoirs near here, which had been hatched and reared by the managers of this fishery : and I noted that although some of them were in unchanged water for over seventeen hours, there were only two dead fish in the tanks; the rest were so strong that they “cut to cover,” almost before we could get a sight of them in their new abode.—Thos. Winder, A.M.I.C.E., Sheffield.

CURE FOR BITE OF Mad Dog.-In searching a number of ancient documents, I recently found the following curious receipt, which may perhaps be of sufficient interest to deserve a place in the pages of SCIENCE-GOSSIP. I preserve the original spelling and punctuation. “An infalliable cure for the Bite of a mad dog brought from Tonquin by Sir George Cobb Bart. Take 24 grains of native Cinnabor 24 grains of factitious Cinnabor and 16 grains of Musk; grind all these together into an exceeding fine powder ; and put into a small tea-cup of Arrack rum or brandy ; let it be well mixed and give it ye person as soon as possible after yo bite ; a second dose of ye same must be repeated thirty days after ; and a third may be taken in thirty days more, but if the symptoms of madness appear on ye persons they must take one of yo above doses immediately and a second in an hour after, and if wanted a third must be given a few hours afterwards. The

W. M. OSMOND.-The micro-photo of the articular process found on the body of an Indian caterpillar is very remarkable. We should advise you to send a photo to Mr. Beddard, Prosector, Zoological Society.

Miss R.-You will find a good description of how to bleach and prepare skeleton leaves, seed-vessels, &c., in the volume ot SCIENCE-Gossip for 1872.

C. S.-Get “Notes on Collecting and Preparing Natural History Objects," edited by J. E. Taylor, published by W. H. Allen & Co., 3s. 6d. Also all the vols. (28. 6d. each, 8 in number) of "The Fauna and Flora of the British Islands," published by the S.P.C.K., except those you name. The Playtime Naturalist" (London : Chatto, 55.) will help you considerably. “Elementary Microscopic Manipulation,” by T. C. White.“Half-hours with the Microscope," by Dr. Lankester (W. H. Allen, 25. 6d.).

S. A. CHAMBERS.—The specimen you sent us was a some. what dwarfed var. of the purple dead nettle (Lamium pur. pureum).

P. T.-Apply to Messrs. W. Wesley & Son, Essex Street, Strand, who keep all sorts of secondhand scientific books on all sorts of subjects.

R. W.-Get Mr. F. Enock's list' of entomological prepara. tions, with the descriptions accompanying them, published two or three years ago by him.

We are informed that a Rambler's Field Club for the Southwest of London is now in course of formation. Apply for information to Mr. W. Andrews, Landseer Street, Batter

R. M. S.-The“ Diatomiste "may be obtained of J. Tempère, 168 Rue St. Antoine, Paris ; price of each number, 45.

T. BROWN (Bolton).-The matrix of the fragment of millstone grit is chiefly a partly decomposed felspar. There is also a secondary deposit of silica.

sea, S.W.

EXCHANGES. WANTED, living British spiders. Micro preparations given in exchange.-John Rhodes, Blackburn Road, Accrington.

WANTED, to exchange foreign postage stamps with moderate collectors of from 1000 to 2000. Also, what offers in stamps for collection of British butterflies and moths, about 650 specimens, in good condition ?-Stanley Morris, School Hill, Lewes, Sussex.

WANTED, foreign shells and unmounted diatoms, polycistines,


forams, &c., in exchange for choice micro-slides of every description, and British marine shells. Foreign correspondence solicited.-R. Suter, 5 Highweek Road, Tottenham, London.

OFFERED, books. Elementary Chemistry," "Elementary, Physics," "Practical Chemistry,” “Inorganic Chemistry, “ Élements of Acoustics," "Our World, its Rocks and Fossils, “Livre des Versions," "German Grammar," " School Hist. of England."and a number of similar books of instruction. Offers wanted in other books, shells, stamps, or garden requisites.Mrs. Heitland, The Priory, Shrewsbury.

"GARDENING Illustrated,” in seven volumes, 1884-90, un. bound. What offers in scientific or other books - A. B., Advertiser Office, Chepstow, Mon.

Trinidad lepidoptera offered for a good classified list of lepidoptera - Kirby preferred. - W. E. Broadway, Royal Botanic Gardens, Trinidad, B.W.I.

OFFERED, good botanical microscopic slides, for books on botany or microscopy.-J. Collins, 147 Muntz Street, Bir. mingham.

Eggs of British ducks and other birds, wanted in exchange for nests and eggs.-W. Gyngell, 28 Wes.borough, Scarborough.

WANTED, cleaned diatoms, foraminisera and polycistina, volvox and other freshwater algæ in vials, insects' eggs, podura, lepisma, fleas, sawflies, cockchafers, large water-beetles, and other insects. State requirements in exchange. - Henry Ebbage, Framlingham, Suffolk.

DUPLICATES.- Trochus striatus, Pupa ringens, Melania sp., Murer aciculatus, Purpura hæmastoma, Helicina beryllina (R), Littorina scutulaia, Acmæa spectrum, and others. Desiderata, exotic mollusca, especially land shells.-Brockton Tomlin, The Green, Llandaff.

Clausilia Rolphii (verified by Mr. Th. Cockerell) from a new Kentish locality, in exchange for other not common British land and freshwater shells.- Rev. J. W. Horsley, Woolwich.

SCIENCE-Gossip, numbers 157 to 205, unbound. Exchange for geological lantern-slides, or offers.-J. T. Cook, Edina, Stoneygate, Leicester.

Helix effulgens, H. calcadensis, H. tapeina, H. achatina, H. plectostoma. H. attaranensis, H. textrina, H. scalpturita, Bulimus domina, B. Nevilliana, B. Beddomiana, offered in exchange for other land or for marine shells. Pecten bifrons, P.plica, P. lemniscatus, in exchange for other species of pecten. -Miss Luter, Arragon Close, Twickenham.

OFFERED, eggs of lapwing, moorhen, razorbill, curlew, missel-thrush, ring dove, rook, black-headed and lesser blackbacked gull, coot, sedge warbler, lesser redpoll, &c., also SCIENCE-Gossip, unbound, sor 1890. Wanted, eggs of raven, switr, ruff, nightjar, hawfinch, kite, goshawk, &c.-G. Nichol. son, 3 Crown Street, Newcastle-on-Tyne.

OFFERED, Beale's “ Micro. in Medicine;" Berkeley's "Introd. to Cryptogamic Botany," in first-class binding; Baker's “Employment for the Microscope,” with all the original plates; “ Alternation of Generations”. (Stenstrup), Ray Soc. ; pure gathering of batrachiosperma for mounting. three years (vols. 6, 7, and 8), bound, works on freshwater algæ, rhizopods, &c.-J. E. Lord, Rawtenstall.

LANTERN slides (photos, statuary, &c.), wanted in exchange for first-class inicro objects.-F. E. Hillman, 1 Harcourt Road, Wallington, Surrey.

WANTED, British land or freshwater shells, or any books relating to same. Will give micro material or slides, or foreign stamps in exchange. - A. Alletsee, 1 South Villas, Kensington Road, Redland, Bristol.

Finely preserved sea-urchins (E. sphæra) with spines-M. incurva, pellucida, T. fabula, M. subtruncata, S. ensis, T. papyracea, H. pellucidum, T. testudinalis, H. ulve, A. cygnea (Scotch), S. corneum, var. pisidiodes, P. fontinale, P. pusillum, S. elegans, H. nemoralis, var. rubella,

&c., offered for British or foreign shells, or lepidoptera.-T. Paterson, 59 Hazelbank Terrace, Edinburgh.

WANTED, Leda caudata, Natica helicoides, Pleurotoma striolata, Vertigo moulinsiana, var. pusilla. Will anyone oblige me with any in return for any of the following rare shells: Cyclostrema serpuloides, Scalaria clathratula, Eulima bilineata, Odostomia nivosa, and others.-T. E. Sclater, Bank Street, Teignmouth.

Wanted, land and freshwater shells of fossils from any formation not in collection, in exchange for Ancylus lacustris, Planorbis vortex, P. carinatus, Limnæa glaber, L. stagnalis, L. peregra, Sphærum corneum, Physa fontinalis, Helix hortensis, H. pomatia, H. hispida, Clausilia rugosa, Pholas candida, and others.-R. D. Laurie, 19 Willow Bank Road, Birkenhead.

Offered, Phillips' “Metallurgy,” Phillips' Geology,” Catlow's “Conchology," Lardner's “Natural Philosophy," &c. (list sent), in exchange for secondary fossils.

AddressM., 56 Clarendon Villas, Brighton.

WANTED, foreign shells not in collection, more especially helices and bulimi. Offered, other shells. Foreign correo spondence invited.-G. R. Sykes, 13 Doughty Street, London, W.C.

Hairs and spines of sea-mouse, in exchange for micro-fungi, unmounted material.-A. Montague, Penton, Crediton.

Marginella glabella (from Mazagan), Haliotus tuberculata (Mazagan), Helix pomatia (Switzerland). Exchange foreign shells not in collection.-L. Montague, Penton, Crediton.

PROCTOR'S "Star Atlas," and " Hall-Hours with the Stars," offered in exchange for books on microscopy. Also Hydra vulgaris and Melicerta ringens for Hydra viridis.-W. F. Kelsey, Maldon.

DREDGINGS and good drift wanted, containing shells, &c., from the fo'lowing places: coast of Scilly, Guernsey, Scotci. Isles, North Sea, Irish coast, near Cork, and from the entrance to the Bristol Channel. Good exchange given.-A. J. R. Sclater, M.C.S., 23 Bank Street, Teignmouth, South Devon.

OFFERED, SCIENCE-Gossip, unbound, clean, complete, 14 vols., 1876 to 1889. Wanted, algological or botanical books, or other exchange.-T. H. Buftham, A.L.S., Comely Bank Road, Walthamstow.

SEVERAL hundred British lepidoptera, in exchange for outdoor plants, roses, and ferns.-W. H. T., 111 Queen's Road, Portsmouth.

Huxley's “Physiography," Nos. 345 to 291 of SCIENCEGossip, and entonological collecting and preserving apparatus, in exchange for science books or micro-slides.-W. E. Watkins, 30 Dalmeny Road, Tufnell Park, London, N.

OFFERED, Cassell's “Natural History," Parts 1 to 8, new edition now appearing.-Chas. Leigh, 47 Sydney Street, London, S.W.

Wanted, nests of goldfinch, long-tailed tit, golden-crested wren, and redpole, during the season, Eggs, shells, of lepidoptera offered in exchange.-William Hewen, 12 Howard Street, Fulford Road, York.

“NATURE,” in weekly numbers, unbound, for the year 1882, three numbers missing ; 1883, five numbers missing ; 1884, complete, in exchange for British land and freshwater shells.T. Place, 50

Townend Street, York. SCIENCE-Gossip, in parts, from January, 1887, to December, 1890. Offers requested in foraminiferous material, papers on the foraminisera, or good micro-slides.-A. Earland, 3 Etoa Grove, Dacre Park, Lee, S.E.

WANTED, British land and freshwater shells. Can offer in exchange Pupa secale, Carychium minimum, &c. AddressH. T. Smith, 11 Oakfield Place, Clifton, Bristol.

WANTED, a few British mosses; will give slides, &c., in exchange. Address--T. B., Conservative Club, Hinckley.

WANTED, a good it.inch objective, or a section cutter, in exchange for bound vols. of " Journal of Royal Microscopical Society," for 1887 and 1888.-F. Coles, 53 Brook's Road, Sroke Newington, London.

OFFERED, Xylophaga dorsalis, Pholas crispata, and Mya arenaria, last two with siphons extended. Wanted, shells not in collection.-J. Smith, Monkredding, Kilwinning.

Wanted, Bowman's Cotton Fibre" and Porter's “Treatise on Silk." State desiderata to R. S. Dawson, Belmont, Shipley,

SCIENCE-Gossip, from commencement to present date of issue, what offers :-Linder, New Brompton, Kent.

BOOKS, ETC., RECEIVED FOR NOTICE. "Coal, and What we Get from It," by R. Meldola (London: S.P.C.K.).-" The Missouri Botanic Garden."-Fifth Report U.S. Entomological Commission-Forest Insects," by A. S. Packard (Washington). - "Annual Report Fruit-Grower's Association of Ontario, 1890."-"Colour Measurement and Mixture," by Capt. Abney_(London: S.P.C.K.). -"Telescopic Work for Starlight Evenings," by W. F. Dennin? (London: Taylor and Francis).-" Zoological Articles," ty Prof. Lankester and Others (Edinburgh: A. and C. Black). Geologists' Association-A Record of Excursions maile between 1860 and 1870," edited by T. V. Holmes and C. 1). Sherborn (London : Edward Stanford).-"Discovery,” No. 5. -“The Conchologist," No. 1.-"The Pedicula and Mall phaga,” by Prof. H. Osborn (Washington: Govt. Office)." Bulletin of Microscopical Society of Calcutta."-"Nature Notes."-"American Microscopical Journal."-"The Microscope. American Naturalist.”—“Canadian Entomologist

." The Naturalist."- The Botanical Gazette."--"The Gentleman's Magazine." "The Midland Naturalist."-"The Garner."-"Feuille des Jeunes Naturalistes,” &c., &c.

COMMUNICATIONS RECEIVED UP TO THE 13TH ULT. FROM: J. E. N.-T. S.-S. A. C.-J. H. C.-I. T. C.-F. T. S.H. E. G.-W. W.-T. W.-A. C. D.-J. W. H.-L. E. A. M. B. M.-I. E. V.-Mrs. H.-H. E.-B. T.-E. F. S.M. W.-W.G.-W. H. S.-J. C.-W. E. R-J. R.-C. 0. S. -D. H. S. S.-S. M.-R. S.-D. M. W.-P.F. K.-M. E. P. -J. H. M.-H, F.-J. E. U.-P. T.-C. S.-E. B.-H. D. W. F. R.-J. W.W.-W. B.-F. C. M.-C. L. B. C.-F. E. II. -H. J. T.-A. H.-M. E. P.-A. A.-A. J. R. S.-T. E. -R. D. L.-Miss L.-J. E. L.-N. F. D.-E. R. S.-L. M. A. M.-J. W. P.-G. N.-Dr. I.-J. C. H.-W. H. TT. H. B.-J. H. W. H.-J. C.-E. B.-T. S. B.-A. J. S. A. E.-J. P.-W. H.-C. L.-W. E. W.-E. H.-W. J. S.J. H.-J. S.-E. M.-R. S. D.-J. S.-H, E. E.-W. M. u. -&, &c.

[graphic][ocr errors][ocr errors][subsumed][merged small][merged small]

N the following few

notes on several of the better-known gums and resins, I have adopted no systematic arrangement. Neither have I said all I should have liked to have said concerning them. But as it was not consistent with the room at my disposal to mention all their various uses, I have suppressed the minor properties and given in

as few words as possible the more interesting features.

I have endeavoured to give the name of the plant producing each variety, together with its uses, native country and other interesting items.

The distinctions between gums, resins and balsams may be briefly tabulated as follows :

Resins are the inspissated or thickened juices of plants. They are generally mixed with an essential oil, are insoluble in water, bụt are soluble enough in either alcohol or the essential oils. Their general characters are inflammability and fusibility. Their ultimate components are carbon, oxygen, and hydrogen.

Gums are soluble in water, but are insoluble in alcohol.

Balsams or Gum resins contain a quantity of gum, are partly soluble in water, partly so in alcohol, or in other words, they take bo:h alcohol and water to perfectly dissolve them. Gum arabic is produced by several species of

No. 319.- JULY 1891.

acacia. It is quite soluble in water, but in alcohol, ether and oils it is insoluble. It forms an acid solution, as permalate of lime is present. Several of the metallic oxides combine with it. It is very nutritious, so much so that the Arabs who gather it nearly live upon it during harvest-time. We import it from the Levant, Barbary, Senegal, Cape of Good Hope, India, Cairo, &c.

Gum senegal the product of Acacia senegal. This is the best kind of Arabian gum. It is much more clear than gum arabic, sometimes entirely white, in drops as large as a pigeon's egg. Its principal use is in the manufacture of silks, muslins, crapes, &c., to give them the requisite amount of stiffness and glaze. It is also mixed with the colours in calico printing to give them solidity.

Gum tragacanth or gum dragon. This is obtained from Astralagus tragacantha. In appearance it resembles twisted ribbons, of a brownish white colour, opaque and rather ductile. When pulverized in a mortar it is of a white colour. The operation of pulverizing is a difficult one, and should be performed in a hot mortar, the gum having been previously heated to 212° Fahr. This gum has a remarkable power of consistence, a small piece swelling up to many times its own size. It has not, however, such a strong power of adhesiveness as gum arabic, but if equal parts of the two be mixed together it forms a nice white gum, very suitable for fastening plants to paper, and other natural history work. The tree is itself a native of Crete.

Gum sandarach. The product of Callitris quadrivalvis is a native of Barbary. This gum is chiefly used in the manufacture of varnishes, for which it is peculiarly adapted. The Turks employ the wood in the construction of their mosques, it being very tough and possessing great lasting qualities. Importation about fifteen tons per annum.

Barbary gum, a very dark-looking kind produced by the Acacia gummisera. In the manufacture of lozenges and confectionery it has valuable qualities.


It calls for no special comment. We import it from the Morocco coast.

Gum gedda, an inferior quality of the foregoing. Reddish colour.

Canada balsam. This is supplied by the Abies balsamifera. It is contained in blisters in the bark. The blisters are punctured, and the balsam is collected as it exudes. This is a most useful substance, being in great demand in a number of manufactures, &c. It is used in cementing lenses together. In microscopy comment is needless, but besides being an excellent preservative, it gives great transparency to the object. We import nearly all of it from America.

Guaiacum. This resin exudes from the Guaiacum officinale, a native of Jamaica and the surrounding islands. A piece of paper treated with tincture of guaiacum takes on a green tint under the violet rays, when exposed to the prismatic spectrum, through oxidization. Red rays destroy the colour. Solubility, 90 per cent. in absolute alcohol. Lignum vitæ, the hardest and heaviest wood known, and which sinks on being placed in water, is the timber of this tree.

Copal. This is the product of several leguminous plants in Africa, East Indies, South America, and Australia. It is generally seen in large angular lumps, often as large as a hen's egg, of a bright yellow colour, and very transparent. The African variety is of a darker colour, and not so transparent ; its surface appears dusty. The Australian is the largest. That from the East Indies is the product of Hymenæa courbaril. In lumps sometimes nearly square and generally covered all over with slight indentations. It is known as gum anime. Chiefly used for fine varnishes.

Gum mastic, the product of Pistacia lentiscus. In small ovoid and round tears about the size of a pea and rather flattened. The tree is a native of Chio and Northern Africa. To obtain the resin the bark is cut transversely, after which the mastic exudes in small drops and either hardens on the bark or falls to the ground. That which falls to the ground is the inferior quality. It has a fragrant smell, and is much used by the Turkish ladies in their toilet. A fine varnish is made from it. Dentists also use it for stopping hollow teeth. About ten or twelve tons are imported annually, mostly from the Levant.

Gum danimar: this is a light-coloured substance which is obtained from the Pinus dammara, native in India, from whence it is exported. It is very useful in making varnishes, especially photographic. It is soluble in benzole, only partly so in alcohol, and is used sometimes as a substitute for Canada balsam.

Gum gamboge: a product of Hedradendron gambogioides, native on the Malabar coast and in Ceylon. It is a gum resin, and is obtained by puncturing the bark of the tree when the flowers begin to appear. We know it best by its appearance in amorphous

masses, but it also takes the form of hollow rolls and solid cylinders. The best hollow rolls come from Siam. From this gum the beautiful yellow colour of gamboge is manusactured.

Gutta-percha : the inspissated juice of Isonandra gutta. When freshly gathered it is rough, dry, slightly soluble and very inflammable. To render it fit for use it is immersed in boiling water ; this softens it and makes it capable of being moulded into any shape, which it retains when cold.

The juice is found between the bark and the wood. Its uses are too numerous to specify, many being too well known.

Caoutchouc, india-rubber, is the product of many euphorbiaceous plants. We get most of it from the Brazils and Central America. In Brazil it is obtained from the Siphonia elastica, which grows to a height of between fifty to sixty feet; and in Central America it is obtained from Castilloa elastica. Most of that we now use comes from Central America, where the juice is simply collected into cups, from incisions made in the bark. To coagulate the milky juice and convert it into rubber fit for exportation, the juice of a vine called “achuca” is mixed with it and so powerful is its action that five or six minutes is sufficient to produce coagulation. The Brazilian method slightly differs. The juice is first collected in clay bowls, it is then smeared over various shaped moulds, made also in clay and taking the form of bottles, balls, spindles, &c. Successive coats are laid on, each one having previously been allowed to thoroughly dry; either in the sun or in the smoke of a fire, which blackens it. When a sufficient thickness is obtained, the clay is washed out leaving the indiarubber ready for exportation. The trees yield twenty or thirty gallons of juice, and when we consider that each gallon will produce two pounds of market india-rubber, the harvest is not so bad. Other trees producing caoutchouc are Siphonia brasiliensis, S. lutea, and S. brevifolia.

Dextrine, British gum, torrified starch. To produce this gum, starch is heated until vapour rises; by this procedure the starch becomes soluble both in cold and hot water, and all its gelatinous character disappears. It can also be made by moistening 1000 parts of dry starch with very dilute nitric acid. It is formed in small blocks and dried in the open air, afterwards being placed in an oven heated to 152°. After this they are pulverized and again dried by heat. In colour dextrine is pale yellow; insoluble in alcohol, more flexible and not so brittle when dry as gum.

Dextrine and starch have the same chemical composition C,H,Og. The gum on the back of postage stamps is dextrine.

Turpentine. This valuable fluid is the product of several trees, principally Pinus palustris and P. tæda. Most of it comes from the United States, generally in large barrels, of the consistence of treacle or honey. The oil is obtained by distillation and the remainder

« EelmineJätka »