two species; for while this is naturally prepared, that from C. Camphora is obtained by artificial means. It possesses the same properties as the produce of Cinnamomum, although it does not evaporate so readily at ordinary temperatures, and its crystals are of a different form. It does not find its way into this country, as it is eagerly bought up by the Chinese at a most exorbitant price, exceeding many times the value they receive for their own produce, although, in the eyes of the European, it is of no greater value. But the Chinese attribute many and excellent virtues to it for which they are ready to pay, and who would forbid them enjoying the opinion at their own cost?

THE PAPAW-FRUIT (Fig. 168).—This is produced by Carica Papaya, Linn., belonging to the family Papayacea. It is now widely distributed and cultivated throughout all tropical countries, but there is no doubt

0

Fig. 168.-Fruit and Leaf of Carica Papaya, Linn. (reduced.) it emanated originally from the Western hemisphere, as students of the new world flora now regard it as a native of Tropical South America. It is a small tree, seldom exceeding twenty feet in height, with a straight unbranched stem, about a foot in diameter at the base, where it is moderately hard, but soft and spongy at the top, and hollow in the centre. The leaves are situated at the top of the stem, on long petioles, diverging almost horizontally from the stem; the blade is as much as two feet in diameter, deeply cut into seven lobes with their margins again cut and sharp pointed. Flowers in racemes produced at the base of the leafstalks. Fruit oblong, from eight to ten inches long, three to four broad; or shaped like a melon with projecting angles, of a dull orange-yellow colour when ripe. The fruit is edible, but rather insipid, and is eaten raw in small quantities, but largely consumed in many parts, when cooked and flavoured

with salt, pepper, and sugar; it is also employed in sauces, and preserved in sugar, especially in the West Indian Islands. The unripe fruits are also pickled, and boiled and eaten as a vegetable prepared in a similar way as turnips are in this country. Throughout the latter part of the globe, the juice of the tree, or an infusion of the fruit and leaves, has a remarkable reputation for rendering the toughest meat tender, as it possesses the power of separating the muscular fibre. Sir Joseph Hooker says "the whole tree possesses this remarkable property." The exhalations emanating from it also have the same power, and fresh meat hung up in the branches is made tender in a surprisingly short space of time. This.practice is largely resorted to in the West Indies. It is also stated that if old hogs and poultry are fed with the fruit and leaves their flesh is rendered extremely tender. The juice of the fruit is used by ladies as a cosmetic for removing freckles from the face, but its most important are its vermifugal properties, it being largely employed as an effective vermifuge; it is also antiseptic.

According to the analysis of the juice by Vacquelin, it contains fibrine, a substance characteristic of all animal tissues, but which occur in other vegetable tissue besides that of the Papaw. The root has a very strong and disgusting odour, similar to that of decaying radishes, and is very acrid, a clear indication of the vermifugal character of the juice. The leaves are employed by the negroes as a substitute for soup. So the uses of the plant are manifold, and for other details respecting it I must refer my readers to the "Botanical Magazine," 2898, where a good plate is given. The plant itself is also cultivated in the Royal Gardens, Kew.

The acidity is infused, in a greater or less degree, throughout all the species. In C. digitata, a Brazilian species, known under the native name of Chamburu, it is most prevalent, and the tree is regarded by the natives of Mayna with as much dread as the upas tree by the Javanese; in this instance with more propriety, as its juice is very poisonous. Pöppig says "that the juice which spirted over his hand when he cut the tree caused itching on the face, and drew a few blisters on the hand." The male flowers are said by Dr. Lindley to have the disgusting smell of human excrement. And what is very remarkable is the fact, that the fruit, although handsome, scentless, and insipid, is untouched by birds or any other creatures, except a spècies of ant belonging to the genus Atta.

(To be continued.)

FRESH-WATER SHELLS.-Mr. H. Wallis, Kew, has sent me some shells identical with those found by Mr. Goulding, attached to the feet of newts and frogs and recorded in the October number as (?) Cyclas lacustris. They prove to be Sphærium corneum, and not S. lacustre (C. lacustris). It will be well to record this, to prevent error.-T. D. A. Cockerell.

PRO

GOSSIP ON CURRENT TOPICS.

By W. MATTIEU WILLIAMS, F.R.A.S., F.C.S. ROFESSOR HENRY DRUMMOND has propounded a theory concerning the white ant which is interesting. He states that there can be no succession of crops "without the most thorough agriculture," and that where man is not doing this work, nature employs other agents. Darwin has shown how the soil of England is tilled by earthworms to the extent of having ten tons of dry earth per acre annually transferred from below to the surface, by passing through their bodies and deposited as their casts. But in tropical countries, where the soil is hard baked by the sun during eight or nine months of the year, and too dry for worms to operate, other agencies are demanded, and Professor Drummond finds one of remarkable efficiency in the termite, or "white ant" as it is called, though it is not an ant at all.

The working termites are blind, and guarded while working by soldiers with eyes. They cannot live above ground on account of their blind helplessness against the many foes whose hunger they are specially qualified to satisfy, but their food is above ground. They eat dead wood, and all kinds of dead vegetable matter, but seem incapable of feeding on living plants. To reach the dead branches of a living tree, they build galleries or tunnels running up the stem, these tunnels being made up of minute pellets of earth brought from below and cemented together. As is well known, their ordinary structures assume great magnitude, mounds, cones, and strange fantastic edifices all composed of subsoil brought upwards. This action is doubtless similar to that of our earthworms, but there is a serious difference otherwise; as the earthworms work for themselves, and others at the same time; and their wages are very small. The damage they do to man and other animals is barely measurable, but the termite is a terrible devastator, he levies black mail on the food, the dwellings and furniture of man (under favourable circumstances a colony can devour a four-post bedstead in twenty-four hours), and of other animals, to such an extent that, in spite of their subsoil ploughing, their extermination from the face of the earth would doubtless be voted a great blessing by an overwhelming majority of men and other tropical anim als, if a fair plebiscite could be taken.

The state of the Lea, of the Thames, and I may add of the Brent in my own neighbourhood, during the past summer months, shows how largely we are dependent on the flushing action of rain for the removal of sewage poison under our present arrange

ments.

This flushing action of rain-water is evident to everybody, but there is another action that is invisible, and therefore far less widely understood. I refer to the purifying action of the oxygen contained in water that has been freely exposed to the atmosphere. A gallon of such water, at the winter temperature of 45° Fahr., contains 2.2 cubic inches

of oxygen; at summer temperature of 70°, 1.8 cubic inch. This oxygen is a most efficient disinfectant; its efficiency in effecting complete purification is simply a question of quantity.

Thus the mere dilution of sewage does something towards its purification, and in addition to this the mixture of water and sewage picks up more oxygen as it travels along the course of a river. It has been estimated that water containing 32 per cent. of sewage is completely disinfected in the course of a journey of one mile, but I may qualify this estimate by adding that the water must be very shallow for this to occur. The case is very different where the sewage of London mingles with the deep water of the lower Thames.

Old-fashioned treatises on Natural Philosophy included "porosity" as one of the general "propertiesof matter." Thus Dr. Lardner says, "there is no substance so dense as to be divested of pores. The celebrated Florentine experiment, performed at the Academia del Cimento in 1661, and often repeated since that time, with the same result, showed that gold itself has sufficiently large pores to admit the particles of water to pass through them." This expe riment was made by filling a globe of gold with water, closing it with a screw, and then squeezing down the globe with a powerful screw. The diminution of its capacity caused a forcing of the water through its pores, the water appearing on the outer surface.

Further experiment, however, shows that such pores are merely accidental, due to the fact that the metal was cast, and to the conditions of the cooling of cast metal. By hammering or rolling the gold,. such pores are filled up. In the "Gazetta Chimica Italiana" is an account of experiments by Sig. A. Bartoli, proving the absolute impermeability of glass to gases under a pressure of 126 atmospheres.

As everybody knows, a very large proportion of the show at the "Inventories" contained no element of new invention whatever, and these mere shop-front cases by their bulk and prominence, dwarfed the really interesting demonstrations of the triumphs of modern invention. Among these are the coal-tar products, of which alizarin may be named as one of the most remarkable and important. Mr. S. B. Boulton, chairman of the British Alizarin Company, states that the yearly consumption of 20 per cent. strength alizarin in Great Britain now amounts to 3400 tons. A ton of this does the dyeing work of eighteen or twenty tons of madder root. At the lowest estimate the alizarin we use in Britain represents 61,200 tons of madder. The cost of this at the average of old prices (from 1860 to 1876) would be £2,907,000, while that of the artificial alizarin is £456,960, thus effecting a saving of nearly two and a half millions per annum in the mere dyeing of some of the colours of some of our textile fabrics. Alizarin. is not an imitative substitute for the tinctorial principle of madder, but a production from coal tar of the actual thing itself. Its production was due to no.

mere accident, but to a series of profound chemical deductions with which the names of Perkin, Caro, Graebe, and Liebermann (especially Perkin) will ever be honourably associated. Dr. Perkin's achievements in the direction of à priori theoretical prophecy, followed by practical realisation, have been by no means limited to such production of alizarin; they were preceded by the earlier aniline colours, and are likely to be followed by further results of a similar character obtained by similar means.

The great international bore proposed by M. J. J. Martinez has been ridiculed by some, but more thoughtful people regard it very differently. M. Martinez asks for a universal subscription to defray the expenses of boring a hole 150 feet in diameter vertically downwards, from the centre of which are to be driven convenient stations, chambers, or tunnels, for the observation of subterranean phenomena. Such a shaft, besides displaying a grand geological section, would help us to determine many of the vexed questions concerning the internal heat of the earth, the probable thickness of its solid crust, the phenomena of internal earth-tides, &c., all of which are intensely interesting to every intelligent man whose whole soul is not completely enveloped in the calf-skin of his ledger.

The proposal to emancipate the ring finger from the thraldom of its immediate neighbours, by cutting through the oblique accessory tendon which renders its independent action so trammelling to pianoforte players, is by no means favourably received by "The Lancet." The improvement of the "execution" of high class pianists is doubted, on the ground that what would be gained in range of action, would be lost in power, and it is further suggested that the division of the lateral bands may be followed by cicatricial union of their severed ends; and again we are told that the records of surgery abundantly prove that no wound can be inflicted with absolute certainty of freedom from mishap in the shape of suppuration, or, it may be, greater evil; and certainly tendons are not the structure least liable to resent operative interference. On the other hand, we are told by the Scientific American (quoted in “Knowledge ” Oct. 2, with engraving of the structure) that Dr. Forbes has performed fourteen entirely successful operations. Still, if I were an eminent pianist dependent on my ten fingers, I should say to them that we will

"Rather bear those ills we have Than fly to others that we know not of."

The failure of the Eucalyptus experiment in the neighbourhood of Rome, where they were planted to counteract the malaria, is disheartening. The eucalyptus flourishes, and the malaria continues. A government commission of enquiry has been appointed on the application of Dr. Tommasi-Crudelli, who regards the facts as instructive, "proving, as they do once more, to what risks of mistake we expose ourselves to, if we hold à priori, that the methods which have resulted in a permanent improvement of one

locality, can be usefully applied to all." He accordingly recommends the exercise of that faculty which distinguishes the philosopher from the vulgar theorist, viz. the suspension of judgment until a broad basis of fact has been obtained. The physical conditions and chemical composition of malarious districts vary considerably, and therefore the remedial measures should be modified accordingly. The eucalyptus has been beneficial in some places, though not in others. If the commission succeeds in determining the cause or causes of this difference, they will then learn where to plant the eucalyptus, and where to adopt other

measures.

Dr. Tommasi-Crudelli recommends arsenic acid, and the alkaline arseniates as the most efficient

protective agents against malaria. I have long advocated the same, and have practically acted upon it, by selecting wall papers containing a limited quantity of that popular bugbear, arsenical green pigments. My conviction was originally based on observations made in Birmingham when I lived there. Arsenical fumes are given off from brass foundries. Birmingham has escaped from cholera, in spite of the "back houses" and "party pumps," which until lately were so abundantly in immediate contiguity to back-yard domestic cesspools. The same has been observed in other places where brass foundries and copper and zinc smelting abound. Other zymotic diseases besides cholera fail to visit these places. Copper and zinc ores, and ordinary samples of the metals themselves, contain small quantities of arsenic which is a volatile metal vaporising at the melting temperature of the constituents of brass, and of brass itself. In "The Gentleman's Magazine" of April, 1881, I said and now repeat, that "if I lived in New Orleans, or any other focus of fever horrors, I would envelope myself to a certain extent in arsenical fumes, by covering my walls with highly-charged arsenical papers, furnishing my rooms with arsenical upholstery, and carrying arseniuretted pocket handkerchiefs; carefully observing the effect in order to stop short at the first warning symptoms of arsenical poisoning."

FREEZING MACHINE.-If J. P. can manage to see Dr. Ure's "Dictionary of Arts, Manufactures, and Mines," edited by Robert Hunt, F.R.S., and published by Longmans, 1867, he will find a full account of "Carré's Continuous Freezing Machine," in vol. ii., p. 401, 402. In a Carré-Leslie machine, containing 25 kilogrammes of sulphuric acid, 4.8 kilogrammes of water can be frozen; after which the acid must be renewed. Concerning the ammonia query :-One gramme of water, at o° C., and under a pressure of 760 mm., absorbs 877 gramme of ammonia, that is, 1149 times its volume of gaseous ammonia. This solvent will have a sp. gr. 88, and freezes at -38° C., forming an odourless jelly-like mass.-Dunley Owen, B.Sc.

in a house at Gateshead-as recorded by Thos. John Bold, in the "Transactions of the Tyneside Naturalists' Field Club," 1857: "Pulex imperator, Westwood. A friend of mine resident in Gateshead, brought an immense flea, which he had found in his bed, for my examination. Not being able to identify it, I forwarded the creature to J. O. Westwood Esq., by whom it has been described as new, under the above appellation, in a paper recently read before the Linnean Society." Mr. Bold remarks that this flea was at "least ten times the bulk of the common species. One consolation, however, I must not omit to mention, to wit, the fact that he was dead when found, and that, so far, no heirs of the imperial line have turned up to claim the family honours; let us hope that he was the last of his race."

keenness of well-bred terriers; the battle was a drawn one, as after some tugging about the box, the belligerents were accommodated with separate apartments. This exhibition of pugnacity was quite a new feature, and afforded considerable amusement.

The tubes and boxes were kept moderately warm, and the fleas soon deposited their glutinous eggs, averaging a dozen from each individual, irregularly scattered; the numbers varied from three, the smallest, to twenty-four, the largest, in each batch; in colour the eggs are of a dingy white,

After considerable perseverance, Mr. George Harkus has succeeded in maturing a few examples of P. irritans in captivity. It would appear that when fleas are permitted to manage their own affairs, they become far too prolific; but it has only been by a series of patient and repeated trials, that Mr. Harkus obtained pupa from imprisoned progeny. Brood fleas were of course essential in order to begin ab ovo, these were placed in glass tubes, or glass-topped boxes, a piece of cloth being laid at the bottom for the reception of the eggs. In order to economise space, two egg-laden females were located in one box, but this arrangement was promptly objected to by the captives, who at once became rampant, confronting each other like microscopic kangaroos, and instantly seized hold by the head and thorax with the