Scientific American Volume 22, No. 1, January 1, 1870 Part 13

"What is wanted is something equally applicable to large or small pieces of iron, and which will answer to ward off the attacks not only of the common atmospheric oxygen, but also remain unaffected by acids or salt waters."

The above from a late number of the SCIENTIFIC AMERICAN states not only the writer's ideas but also one of the greatest wants of the age. Iron is daily being put to more and more varied uses. On land the great question is what will prevent rust; on water, what will prevent rust and fouling of bottoms of iron vessels. We will briefly summarize the many patents granted for this purpose.

Eight are for sheathing of various kinds put on in varied modes. The most practicable of these is a system prepared by Daft. Most iron vessels are now constructed by every other plate lapping the edges of the one between. He proposes, instead of having the plates all the same width, to have one wide and one very narrow plate. This would leave a trough between the two wide plates of the depth of the thickness of the plates. He proposes to force into this trough very tightly pieces of teak, and to the teak, thus embedded, he nails a sheathing of zinc. The zinc is kept clean by slowly wearing away of its surface from action by contact with the iron and salt water.

There are four patents, in which various, so-called, non-conducting coats are put on the iron, and copper pigment in some form put on over them. These have been specially condemned in England, as no matter how good the non-conducting substance--and many are so only in name--it will become rubbed off at some points, and there the bottom will be eaten both by salt water and action of copper.

Coal tar and asphaltum are the subjects of patents in various forms.

One patent claims rubber or gutta-percha dissolved in linseed oil as a vehicle in which to grind the pigment; another the same dissolved in naphtha or bisulphide of carbon as a pigment; another hard rubber, ground.

Enameling with different materials is proposed by some, while one proposes to glaze the bottoms so that barnacles and gra.s.s would find a slippery foothold.

Combinations of tallow, resin, and tar--mineral and pine--are patented mostly to use over other paints.

Coal tar, sulphur, lime, and tallow, are the subject of one patent; guano, red lead, and oil of another; while sulphur and silica are claimed by a third.

Paints containing mercury, a.r.s.enic, and even strychnine, are the subjects of several patents. A mixture of coal tar and mercurial ointment of one.

Galvanism is proposed to be used in various ways--strips of copper and zinc, or by galvanizing the plates before use. Black lead finds a place in many compositions.

One patent, by a complicated process, effects a union of metallic zinc and iron; this, granulated and ground fine, then mixed with red lead and oil, makes the paint. It is said to be the best of all the patented stuffs.

It is astonishing how many use oils derived from coal, peat, or resin, and tars of the same.

There are about fifty patents for this object and with all of them before their eyes, the British Society for the Advancement of Art still hold the $5,000 reward for a pigment or covering which will perfectly protect from rust and fouling. However they may puff their products for selling, no one has the temerity to claim that they deserve the reward.

We think it would be difficult to find so many expedients ever before adopted for the accomplishment of any one object. These are all English patents, England having necessarily been obliged to use iron for vessels from its cheapness as well as its consequent first introduction there.

In the United States no patents worth mentioning have been granted.

The first requisites for a pigment or coating for iron are, that it should not contain any copper--the corrosive action of that metal on iron being intense. Then if for work exposed to air it should form such a coating as to be impervious to that gaseous fluid, and be so const.i.tuted chemically as not to be oxidizable by it; if under water--especially sea water--to be impermeable to moisture, so elastic as not to crack, so insoluble as not to chloridize; to form a perfect, apparently hard, coating: and yet wear just enough to keep off incrustation, barnacles, or growth of gra.s.s. In fact, this slow wearing away is the only preventive of fouling in iron vessels. Wooden bottoms may be poisoned by solutions of copper--and that metal has no superior for such uses, especially when it is combined in mixture with mineral or resinous tars and spirits--these compounds, however, are not only useless on iron bottoms, but also injurious. What then is _the_ substance: 1st. One of the oxides of lead (red lead). 2d. The purest oxide of iron to be found. If properly made these articles can be carried to no higher state of oxidation, and respectively, as to order named, they have no superiors for body and durability. By preference, 1st, red lead, either out of or under water; 2d, Prince's oxide of iron only, out of water. The color of these paints--the first red, the latter brown, may be hidden by a coat of white or tinted color. If there were to be had in combination as a white paint, an oxide of lead and an oxide of zinc, it would be immensely superior to either, but that such has not been produced is rather the fault of carelessness than of possibility.

Zinc protects iron with great effect, but it is too rapidly worn in the effort to be of lasting value. Hence the great desideratum, the yet to be, the coming pigment is a white oxide of lead or a combined white oxide of lead and white oxide of zinc, without sulphates or chlorides.

Those materials answer very well for work exposed to atmospheric air, and perhaps nothing will ever be found better; but a different need is that for salt water. No mere protector of the iron from rust can be found superior to pure red lead and linseed oil. We have seen a natural combination of zinc, lead, and iron, which, in our experience, ranks next; but the zinc is acted on by the chloride of sodium, and wears away too much of the material. Red lead, however, while covering the iron perfectly and effectually preventing rust, and also having but little disposition to chloridize, when it does, will foul both with gra.s.s and barnacles. Hence, the first desideratum being obtained, how shall we accomplish the other. The prevention of fouling may be accomplished in two ways: First, cover the vessel's bottom with two or even three coats of red lead, and give each time to dry hard. Then melt in an iron pot a mixture of two parts beeswax, two parts tallow, and one part pine resin; mix thoroughly, and apply hot one or two coats. This mixture may be tinted with vermilion or chrome green. It is not necessary to use any poisonous substance, as it is only by its softness and gradual wear that it is kept clean. Second, mix red lead and granular metallic zinc, ground fine, or such a mineral as we have mentioned--crystalline and granular in its character. Put on two or three coats, and allow each to set--they will never dry hard. The zinc will slowly wear off, keeping the whole surface clean, while there will be left enough coating of the lead to preserve the iron from rust. The oil I would urge for these pigments is linseed--as little boiled as possible, to be thinned with spirits of turpentine. There seems to have been a mania for mixtures of tar and resins, their spirits and oils; my experience fails to show me any advantage for them on an iron bottom. They have neither elasticity nor durability, while linseed oil has both in a pre-eminent degree, and is no more likely to foul than they, when in a combination that does not dry hard. Besides they are difficult to grind, inconvenient to transport, and offensive to use.

Perhaps we have not, in the opinion of some, answered the want expressed in the first paragraph. No pigment with the requisites of durability and cheapness will resist the attacks of strong acids on iron. The first we have mentioned will--all such as may float in our air from factories or chemical works. Chemically it is converted by nitric acid and chlorine into an insoluble substance--plumbic acid or the cyanide of lead. An experience of more than three years, with almost unlimited means at our command for experiment, demonstrates to us that we have indicated the means of filling the other requisites asked for. It may be that something new will be discovered, but we doubt it. Let any one tread the road we have trod, investigate and experiment where and as much as we have, and, if that place is, where we have not, and their experience will be the same as ours.

THE BANANAS AND PLANTAINS OF THE TROPICS.

[For the Scientific American.]

Poets have celebrated the banana plant for its beauty, its luxuriance, the majesty of its leaves, and the delicacy of its fruit; but never have they sufficiently praised the utility of this tropical product.

Those who have never lived in southern countries are unable to fully appreciate its value. Some look even with indifference upon the gigantic cl.u.s.ters of this fruit, as they are unloaded from the steamers and sailing vessels; and yet they deserve special attention and admiration, for they are to the inhabitants of the torrid zone, what bread and potatoes are to those of the north temperate zone.

The banana tree is one of the most striking ill.u.s.trations of tropical fertility and exuberance. A plant, which in a northern climate, would require many years to gain strength and size, is there the production of ten or twelve months. The native of the South plants a few grains, taken from an old tree, in a moist and sandy soil, along some river or lake; they develop with the greatest rapidity, and at the end of ten months the first crop may be gathered, though the cl.u.s.ter and bananas are yet small; but the following year one cl.u.s.ter alone will weigh some sixty or more pounds. Even in the South they are always cut down when green, as they lose much of their flavor when left to ripen or soften on the tree.

The trunk of the tree, if it may be so called, and which grows to a hight of some fifteen feet, is formed only by the fleshy part of the large leaves, some of which attain a length of eighteen feet, and are two and a half feet in width. While from an upper sprout you perceive the large yellow flowers, or already formed fruits, you see underneath a cl.u.s.ter, which is bending the tree by its weight.

The plantain tree is much the same as the banana, with the difference, however, that its fruit cannot be eaten raw, like the banana's, and that it is much larger in size. Almost every portion of the banana tree is useful. First of all, the nutritious fruit. The plantains when green and hard, are boiled in water or with meat like our potatoes, or they are cut in slices and fried in fat, when they are soft and ripe. There is a singularity about the boiled plaintain, worthy of being mentioned. Pork especially, and other meats are so exceedingly fat in the tropics that they would be most disgusting or even impossible to eat with either bread or potatoes, but the plaintain seems to neutralize or absorb all the greasy substance, and the fattest meat is thus eaten by natives and foreigners without the least inconvenience.

Ripe bananas are mashed into a paste, of which the natives bake a sort of bread, which is very nourishing, though somewhat heavy. This paste, which contains much starch, can be dried, and thus kept for a length of time, which is often of great service to mariners. The young sprouts are used and prepared like vegetables, and the fibrous parts of the stalks of the majestic leaves are used like manilla for ropes and coa.r.s.e cloth.

The utility of the leaves is a theme rich enough to fill a volume; they are used to cover the huts, for table-cloths and napkins, or wrapping paper. The dough of bread, instead of being put in a pan, into the oven, is spread on a piece of plantain leaf; it will neither crisp nor adhere to the bread when taken out. The Indians of America carry all their products, such as maize, sugar, coffee, etc., in bags made of this leaf, which they know how to arrange so well, that they transport an "arroba,"

or twenty-five pounds any distance without a single grain escaping, and without any appliance other than a liana or creeper to tie it up with.

As to the medicinal qualities of the leaves, they are numerous. Indeed, a book has been written upon them. I speak, however, from my own experience. The young, yet unrolled leaves are superior to any salve or ointment. If applied to an inflamed part of the body, the effect is soothing and cooling, or if applied to a wound or ulcer, they excite a proper healthy action, and afterwards completely heal the wound.

Decoctions made of the leaves are used among the natives for various diseases.

Since the beginning of the world this plant has ranked among the first in the Flora of Asia. The Christians of the orient look upon it as the tree of Paradise which bore the forbidden fruit, and they think its leaves furnished the first covering to our original parents. According to other historians, the Adam's fig was the plant, which the messengers brought from the promised land to Moses, who had sent them out to reconnoitre. "It is under the shade of the _musa sapientium_, that," as recorded by Pliny, "the learned Indians seated themselves to meditate over the vicissitudes of life, and to talk over different philosophic subjects, and the fruit of this tree was their only food." The Oriental Christians, up to the present date, regard the banana almost with reverence; their active fancy beholds in its center, if a cut is made transverse, the image of the cross, and they consider it a crime to use a knife in cutting the fruit.

In the holy language of the Hindoo, the Sanscrit, the Adam's fig is called "modsha," whence doubtless, the word "musa" is derived. It is generally believed that the plant came from India to Egypt in the seventh century; it still forms a most important article of commerce in the markets of Cairo and Alexandria. In the year 1516, the banana was brought to the West Indian Islands by a monk, since which time it has rapidly spread over the tropics of America, and is found to the twenty-fifth degree north and south of the equator. It is equally indispensable and is appreciated by the immigrant and by the native as a beautifier of the landscape; affording shelter from the sun and rain, and giving bread to the children; for if every other crop should fail, the hungry native looks up to the banana tree, like a merchant to his well-filled storehouse.

PUTTING UP STOVES.

BY MARK TWAIN.

We do not remember the exact date of the invention of stoves, but it was some years ago. Since then mankind have been tormented once a year, by the difficulties that beset the task of putting them up, and getting the pipes fixed. With all our Yankee ingenuity no American has ever invented any method by which the labor of putting up stoves can be lessened. The job is as severe and vexatious as humanity can possibly endure, and gets more so every year.

Men always put their stoves up on a rainy day. Why, we know not; but we never heard of any exception to this rule. The first step to be taken is to put on a very old and ragged coat, under the impression that when he gets his mouth full of plaster it will keep the shirt bosom clean. Next, the operator gets his hand inside the place where the pipe ought to go, and blacks his fingers, and then he carefully makes a black mark down the side of his nose. It is impossible to make any headway, in doing this work, until this mark is made down the side of the nose. Having got his face properly marked, the victim is ready to begin the ceremony.

The head of the family--who is the big goose of the sacrifice--grasps one side of the bottom of the stove, and his wife and the hired girl take hold of the other side. In this way the load is started from the woodshed toward the parlor. Going through the door, the head of the family will carefully swing his side of the stove around and jam his thumb nail against the door post. This part of the ceremony is never omitted. Having got the family comfort in place, the next thing is to find the legs. Two of these are left inside the stove since the spring before. The other two must be hunted after, for twenty-five minutes.

They are usually found under the coal. Then the head of the family holds up one side of the stove while his wife puts two of the legs in place, and next he holds up the other while the other two are fixed, and one of the first two falls out. By the time the stove is on its legs he gets reckless, and takes off his old coat, regardless of his linen.

Then he goes for the pipe and gets two cinders in his eye. It don't make any difference how well the pipe was put up last year it will always be found a little too short or a little too long. The head of the family jams his hat over his eyes and taking a pipe under each arm goes to the tin shop to have it fixed. When he gets back, he steps upon one of the best parlor chairs to see if the pipe fits, and his wife makes him get down for fear he will scratch the varnish off from the chairs with the nails in his boot heel. In getting down he will surely step on the cat, and may thank his stars that it is not the baby. Then he gets an old chair and climbs up to the chimney again, to find that in cutting the pipe off, the end has been left too big for the hole in the chimney. So he goes to the woodshed and splits one side of the end of the pipe with an old axe, and squeezes it in his hands to make it smaller.

Finally he gets the pipe in shape, and finds the stove does not stand true. Then himself and wife and the hired girl move the stove to the left, and the legs fall out again. Next it is to move to the right. More difficulty now with the legs. Move to the front a little. Elbow not even with the hole in the chimney, and the head of the family goes again to the woodshed after some little blocks. While putting the blocks under the legs, the pipe comes out of the chimney. That remedied, the elbow keeps tipping over, to the great alarm of the wife. Head of the family gets the dinner table out, puts the old chair on it, gets his wife to hold the chair, and balances himself on it to drive some nails into the ceiling. Drops the hammer on wife's head. At last he gets the nails driven, takes a wire swing to hold the pipe, hammers a little here, pulls a little there, takes a long breath, and announces the ceremony concluded.

Job never put up any stoves. It would have ruined his reputation if he had. The above programme, with unimportant variations, will be carried out in many respectable families during the next six weeks.

THE MAGIC LANTERN.