Chapter III: Sewage Disposal by Discharge Into River or Sea

We will next deal with the conditions which should be fulfilled where it is sought to utilize a river or the sea into which to cast the sewage of a town. If it can be ascertained beyond question that at the proposed point of discharge the currents at all times will carry the sewage right away, and will not at the same time produce mischief at a distance (which is often omitted from the consideration), then that arrangement may be accepted as a good one. This, however, seldom occurs.

A river has been looked upon by manufacturers and local authorities as the natural carrier of their refuse from their district. This view has been persevered in, in spite of the River Pollution Prevention Act of 1876, which is practically a dead letter. The public, however, who use a river either for pleasure purposes or for obtaining their water supply, have of late years grown more and more united in their efforts to stop this abuse; and there is no doubt that these efforts will eventually succeed. In a paper which we read last year at the Congress at Glasgow, we pointed out the steps that were necessary to be taken to render this act operative, and we refer our hearers to that paper if they wish to follow the matter further. The effect of discharging sewage matter into a river has been the subject of much controversy among chemists. Some allege most positively that the injurious properties in the sewage are indestructible. This has led to alarmists demanding that under no circumstances ought sewage to pass untreated into a river.

We have given considerable attention to this vexed question, as it requires to be grasped by any engineer who has to advise on the selection of sewer outfalls, and it appears to us that the balance of evidence is against the alarmists. Every river has a certain power of oxidizing impurities in proportion to the extent of oxidation of the river itself. Besides this, there are the powerful purifying influences exercised by the plants and animalcules which exist in rivers.

It has been ascertained that entomostraca consume dead animal matter; and where this is wanting they do not live, but where it is in abundance they thrive. It follows, then, these minute animals exercise an important function in absorbing sewage impurities. They multiply prodigiously in these impurities, and are both created by them and fed upon them, converting foul and dangerous matters into harmless ones, in a similar way to that which we have referred to as nitrification when speaking of the action of bacteria in the soil. Considering that these organisms arise from and are fed on concentrated filth, it is obvious that they cannot live when the conditions favorable to their existence disappear. This would be the case when the sewage is discharged into a large volume of water with a different temperature to that which suits them, and with powerful oxidizing influences at work. These conditions, added to the difficulty they must experience to find their natural food--namely, concentrated sewage--where the sewage matter becomes so greatly diluted, accounts for the fact that in a short run of a good river sewage impurities largely disappear. The action of weeds and plants also aids purification to a very large extent. Minute plants, such as confervoid algæ and the like, also assist in oxygenating the river, as when exposed to light they decompose carbonic acid, and liberate oxygen.

The practical question which has to be answered in every case where sewage is proposed to be discharged into a river requires to be approached from two points. The first is whether a nuisance will be caused at the spot to which objection would be taken. If this is likely to be the case, then the fact that the sewage will get purified in a short run of the river does not meet the objection. The second point requires a careful consideration of the condition of the river, both from an engineering as well as from a chemical and biological point of view. Decisions on these matters have too often been arrived at in a rough and ready way. They require skillful treatment, as the interests--both commercial and hygienic--which are affected are too great to permit of them being dealt with by any who are not well informed and careful. The general conclusions which we deduce from our observations are as follows:

1. That chemical precipitation is not so necessary now as it was considered to be a few years ago, in cases where land for irrigation is not procurable.

2. That the efforts to profitably remove the manurial elements from sewage by chemicals not having been successful, the system should be adopted _per se_ only where a filtration area cannot be obtained.

3. That the success which has attended the construction of filtration areas where the land is clayey, and the successful results which have been obtained from a combined straining of sewage and of subsequent filtration through small areas of artificial filters, point to the adoption of one or other of these systems in many cases where chemical treatment would previously have been advised.

4. That the injurious effects of passing untreated sewage into a river depend upon not merely the relative volumes of the sewage and the river, but chiefly upon the power of the river to oxidize the sewage, which power is in proportion to the extent of oxidation of the river itself.

NEW YORK CITY STREET CARS.

An article in the local news columns of the _Tribune_ says:

The loud outcry made a few years ago against the old fashioned plush covered spring cushions, then used in street car for seats and backs, caused them to be removed and set car builders at work to make a car that would be light, healthy, and comfortable. The general plan of perforated wooden seats with plain backs has been adopted by all the companies. They are covered with a fine quality of heavy Axminster carpet during the winter, and in the summer nearly all the cars have only wooden seats and backs. Open cars are used on a number of routes during the summer, and this is conducive to the health of passengers. The only particular difference in the furniture of the cars is the mats used on the floor. Seven of the lines use sectional wooden mats of plain or ornamental design, while three retain cocoa mats. Wooden mats are the easiest to clean. Cocoa mats retain moisture on damp or rainy days, and emit a musty odor. There are four sets for each car, and they are changed every trip on rainy days.

The First and Second Avenue routes, under one management run 150 cars; the Third Avenue, 180; the Fourth, 75; the Sixth, 88; the Broadway and Seventh, 135; the Eighth and Ninth, 160; and the Tenth, 120. At the stables of each the same general arrangement for cleaning cars is used, while the details only are different, being regulated by the judgment and experience of superintendents. From six to fifteen men are employed for cleaning cars by the different companies.

After every round trip that a car makes, it is taken to the stable, the mats are taken off the floor, and two men with brooms and specially constructed brushes give it a thorough sweeping and brushing. After a car makes its last trip at night, it is run upon what is termed the washstand, which is a large turn table surrounded by hydrants. Everything movable is taken out of it, and water is played from a hose on the inside and outside, while four men with scrubbing brushes and stiff brooms remove whatever dirt has accumulated during the day. After this operation the car is run upon a side track, and two men dry the inside and polish the windows.

While passengers find fault with the untidiness of street cars, superintendents have a word also of complaint against passengers. If men would not convert a car into a spittoon for the reception of cigar stumps, tobacco spit, and quids, and a garbage box for nut-shells, fruit rinds, cores, and pits, the remnants of lunches and old papers, it would be much easier to keep up a cleanly appearance. Section 167 of the Sanitary Code, which provides that no soiled article of clothing or bedding shall be carried on street cars, except on the front platform, is strictly enforced by all the companies, and it is worth a conductor's position if he is proved derelict in this respect.

Nearly all the car companies build their own cars, and all have repair shops at their stables, and as soon as a car is damaged by a collision it is sent at once to the shop and repaired. Men are detailed to keep a strict watch over all the working parts of cars.

No metal or plate has yet been found of which to make a hand railing that will keep bright and untarnished. Many experiments have been tried, but the hardest plate that can be obtained will not stand the friction of the hands longer than two months, before the plated metal will show through. Cars are painted and varnished at least once a year. The various parts of the car last different periods. The wheels average about eighteen months on long routes; on short routes, about two years. Steps and platforms last about five years. There is no particular limit for the floors and framework, as they are but little worn. Cars are frequently built up from an old floor or framework, but at the end of about fifteen years there is but little left of the original car.

RINGS OF SMOKE.

When, by means of a tube of from 2 to 5 millimeters in diameter, we gently blow tobacco smoke against a wet pane of glass, we produce very fugitive rings. If we operate with a closed vessel the rings are fixed, the current being itself uniform. But the experiment that shows the phenomenon perfectly is the one that consists in rendering the current automatic by means of an aspirator--an arrangement analogous to that devised by Mr. Nickles for analyzing the flame of a candle. A tapering glass tube or, better, a metallic blow pipe traverses a cork which hermetically closes a large bottle having a cock beneath and filled with water (Fig. 1). The nozzle of the blow pipe entering the center of the flame, and the cock being open, the liquid flows, and a column of white smoke descends vertically to the surface of the water, where it forms several concentric rings whose relief soon increases with the thickness of the heavy smoke, which finds no exit. These rings have a diameter so much the greater in proportion as the current is stronger (Fig. 2).

Unfortunately, the number of the rings soon diminishes in measure as the stratum of smoke that remains upon the surface of the water becomes thicker. Finally, there remains but a single ring, which has a thickness in the center of more than 0.015 m. (Fig. 3).

Instead of the smoke of a candle, we may employ that of a cigar or of a tobacco pipe. We thus avoid a deposit of fatty matter, which, in the first case, soon clogs up the tube, if it is too fine a one, and thus puts a stop to the experiment.

Several circumstances are known under which rings or crowns are produced. (1) For example, in the spontaneous combustion of phosphureted hydrogen, the resulting white vapors of phosphuric acid rise, and roll round in horizontal white crowns when the air is calm (Fig. 4). These crowns, whose diameter keeps on increasing, end by separating into strips that dissolve in the humidity of the air. (2) The crowns that we sometimes observe in calm weather around cannons at the moment of firing have the same origin, although they are of a different nature, and spread horizontally to a certain distance. With vertical howitzers the crowns are horizontal, and very beautiful when seen from beneath, since they rise vertically. (3) As well known, a cardboard box having two apertures in the center of two opposite sides, when filled with smoke and struck upon one of these sides, allows the escape through the opposite aperture of curling rings of smoke. (4) Steam escaping into the open air, through the intermittence of a vertical eduction pipe, sometimes makes its exit in the form of circular or elliptical crowns.--_La Nature._

AN IMPROVED HYACINTH GLASS.

The hyacinth is a native of the East. When it was introduced into England, in 1596, only four varieties of it were known, but the Dutch gardeners soon made wonderful progress in its culture, and, along toward the end of the sixteenth century, had produced at least two thousand varieties.

This plant is well adapted for house decoration in winter, when flowers are rare. Its culture requires but little care. When the bulbs have taken root in a dark place they are gradually brought into the light, and placed where the temperature is moderate.

Is a regular changing of the water favorable to the development of this plant? Many florists doubt it, and it is often recommended not to change the water, but only to replace that which has been lost through evaporation. Others are of a contrary opinion, and assert that the less favorable results that are obtained when the water is changed are merely due the fact that the roots are injured when the plant is taken out of the glass.

With the old style of glasses it has always been difficult to renew the water regularly and keep the glass clean, but this inconvenience has disappeared in the glasses invented by Mr. J. C. Schmidt, of Erfurth.

Fig. 1 represents one of these glasses, and Fig. 2 shows the details. As may be seen, the tube, a, which contains the bulb, may be removed from the glass, b, without the plant being touched or its roots disturbed. The glass, b, may thus be easily cleaned and filled with fresh water as often as necessary.--_Science et Nature_.

THE BOTANICAL CLUB OF THE AMERICAN ASSOCIATION.

The meeting of the American Association last year at Minneapolis attracted a larger attendance of botanists than usual. Without much consultation, a meeting of those interested in botany was called, a president and a secretary were chosen, and discussions, short communications, and papers upon botanical subjects listened to. The Botanical Club was thus inaugurated; and before the close of the session it was decided to do what was possible to secure a larger attendance of botanists at the next gathering in Philadelphia.

Although during the interim the prospect of a good attendance at the Philadelphia meeting had been fair, the most sanguine were surprised to find that, as early as Monday preceding the opening, a number of botanists had arrived in the city; and by the following day a larger gathering could have been assembled than the total attendance at Minneapolis.

The first meeting of the club, of which several were held between Friday and Wednesday, was responded to by an attendance of about thirty--a little below the average attendance for the subsequent meetings. Prof. W. J. Beal, of Lansing, Mich., the president, took the chair; and Prof. J. C. Arthur, of Geneva, N. Y., was appointed secretary to fill the vacancy caused by the absence of Professor Coulter. A paper by Dr. N. L. Britton, of New York, on the composition and distribution of the flora of New Jersey, was read. The surface-features of the State were given, and the corresponding vegetation described. The work of cataloguing the plants is being done under the supervision of the State geological survey. The list at present has reached the very large total of nearly fifty-five hundred.

Prof. C. R. Barnes, of La Fayette, Ind., spoke of the course of the fibro-vascular bundles in the leaf-branches of Pinus sylvestris. The two needle-leaves at the end of each short lateral axis contain each a paired bundle. The question at issue was whether this structure represented one or a pair of bundles, or whether it might not be a segment of the fibro-vascular ring of the stem. A study of the early stages shows that the first change in the stem is to divide the fibro-vascular ring into halves at right angles to the plane of the leaves; and subsequently these divide again, sending one branch of each to each leaf. The paper led to much discussion by Professors Buckhout, Macloskie, and others.

Dr. Bessey, of Ames, Ia., described the opening of the flowers of Desmodium sessilifolium. They expand partially in the usual manner, then remain stationary till a particular sensitive spot at the base of the vexillum is touched by an insect, when the wings and keel descend with a jerk, the stamens are released, and the insect dusted with pollen.

Professor Mackloskie, of Princeton, N. J., described the method of cross-fertilization of Geranium maculatum by bumblebees. Professor Dudley, of Ithaca, N. Y., spoke of the torsion of stems of Eleocharis rostellata, and also on the protogynous character of some species of Myriophyllum. Mr. William H. Seaman, of Washington, D. C., advocated the use of rather thick oblique sections in studying the structure of the fibro-vascular bundle--a method that called forth a very strong protest.

Professor W. J. Beal gave a paper concerning the manner in which certain seeds bury themselves beneath the soil, which was discussed by Professors Bessey, Rothrock, and others. A paper by Prof. W. R. Lazenby, of Columbus, O., on the prolificacy of certain weedy plants, embraced careful estimates of the average number of seeds produced by individual plants among various kinds of weeds. Dr. J. T. Rothrock, of Philadelphia, addressed the club on some phases of microscopic work, alluding particularly to microscopic work, alluding particularly to micro-photography, its importance to the investigator, and the ease of execution.

Dr. Asa Gray called attention to the interesting discovery of Mr. Meehan regarding the mode of exposing the pollen in the common sunflower. He had found that, contrary to the teachings of the text books, the pistil and stamens develop together until reaching full length, when the filaments rapidly shorten, and the anther tube is retracted, exposing the style covered with pollen, the further changes being the same as usually stated. This Mr. Meehan construed to be a device for self-fertilization; while Dr. Gray showed that, although bees carried pollen from one flower to another of the same head, they also carried it from head to head, which constituted crossing in the fullest sense. An interesting discussion followed, in which Professor Beal suggested that an excellent experiment would be to cover up the heads and ascertain if any fertile seeds were produced. Dr. Gray thought it very likely there would; for, when cross-fertilization is not effected, self-fertilization often takes place. Mrs. Wolcott had proved this to be so; for, in covering up the flowers to keep birds away, she found that plenty of seeds were formed.

Dr. George Vasey, of Washington, gave some notes on the vegetation of the arid plains, which was followed by observations on the curvature of stems of conifers by Dr. Bessey, in which he noted the bending of stems one, two, and even three years old.

Mr. THOMAS MEEHAN discussed the relationship of Helianthus annuns and H. lenticularis; showing that there was a constant difference in the form of the corollas, the former being campanulate, and the latter tubular. The two are treated as one species in Gray's Synoptic Flora of North America; the one being considered a cultivated form of the other, a view from which the speaker dissented. Mr. Meehan then spoke upon the fertilization of composites; concluding that the arrangements were such as to favor self-fertilization, which is opposed to the generally accepted view.

Prof. L. M. Underwood, of Syracuse, N. Y., gave some statistics concerning the North-American Hepaticae. Of the two hundred and thirty-one species found north of Mexico, a hundred and twenty are pecular to America; fully one-half the latter are not represented in any public or private herbarium in this country.

In a paper on the nature of gumming, or gummosis, in fruit-trees, Prof. J. C. Arthur detailed experiments from which the conclusion had been reached that it was due to a deorganization of the cell-walls of the tree through the influence of some fungus, but not necessarily of a specific one.

It had been produced experimentally by the bacteria of pear-blight and by Monilia fructigenum, the fruit-rot fungus; although the most common cause is doubtless the Coryneum, first described by Oudemans in Hedwigia.

At the final meeting the Committee on Postal Matters then gave its report. This committee was appointed at Minneapolis to inquire into the various obstructions which the postal authorities throw in the way of exchanging specimens of dried plants. The efforts of the committee had been directed toward securing the passage of specimens bearing the customary written label at fourth-class rates of postage. The Decision of the Postmaster-General was read, stating that the present law could not be construed to permit the passage of specimens with written labels except at letter-rates, but expressing a willingness to bring the matter, at the proper time, to the attention of Congress, the Canadian authorities, and the congress of the Universal Postal Union. Some discussion followed; and a motion was carried to continue the committee, and also instructing the president and secretary of the club to draft resolutions to be presented to the section of biology, in order to still further promote the objects in view.

These resolutions were acted upon by the biological section on the following day. Dr. Bessey was chosen president, and Professor Arthur secretary, for the next year.

Besides the reading of papers, the club took several excursions. On Saturday they went to the pine-barrens of New Jersey, about fifty participating. On Monday a party visited the ballast-grounds during the morning, and upon their return inspected the library and herbarium of Mr. I. C. Martindale, of Camden, N. J. In the evening of the same day the Botanical section of the Philadelphia Academy of Science entertained the club, the Torrey Botanical Club of New-York City, and other invited guests, at the rooms of the Academy. About three hundred were present, and a thoroughly enjoyable time experienced. On the afternoon of Tuesday the club and its friends, in all about eighty, made an excursion to the Bartram Gardens, one of the most interesting historical spots to botanists in this country; and the club then adjourned.

In reviewing the attendance of botanists in Philadelphia, and the work of the Botanical Club, there is much reason for congratulation. About a hundred entered their names on the register of the club as botanists, or about eight per cent. of the total attendance, one-half of whom are widely known for their attainments in the science. There was no lack of interesting papers and free discussion. Besides the important measures already referred to, the club was instrumental in securing the appointment of a permanent committee of the Association to encourage researches on the health and diseases of plants. But, above all, the augmented facilities for intercourse and acquaintanceship, and the impulse imparted to individual workers, through the influence of the club, are a sufficient _raison d'étre,_ and a promise of usefulness of the future.--_Science_.

PETROLEUM WELLS.

The theory of artesian and of spouting petroleum wells is entirely different. While the latter owe their operation to an internal pressure, due to gases accumulated within a confined space, the former are due to the pressure of a liquid which is flowing--a pressure caused by a sheet of water of unequal height; and they spout with so much the more force in proportion as the difference of level between the orifice and starting point of the sheet of water is greater.

Petroleum reservoirs, or pockets, contain, along with the petroleum, gases, salt water, sand, and foreign substances of varying nature. The liquids and gases in these pockets are often submitted to very great pressure. If we make an aperture in the pocket, there will occur, by reason of the tension, and according to the location of the aperture, a sudden exit of gas, petroleum, salt water, etc. Yet it may happen that as the sounding well has been bored through the upper part of the pocket, where the gases are accumulated, only the latter will make their exit without any trace of petroleum. Under such circumstances the appearance of inflammable gases at the surface indicates pretty certainly the presence of inflammable liquids in the region explored, and will justify further exploration or the fitting of suction pumps to the well holes.

It will be understood that a natural flow of petroleum will occur only so long as the pressure is sufficient, and that a pocket may cease to give mineral oil spontaneously, even though it may still contain large quantities of it. This is the reason why at present spouting wells are not abandoned when they cease to operate, but are worked by lift pumps. The three diagrams, 1, 2, and 3, will give an idea of the different configurations that petroleum pockets may present. In No. 1, as the well hole reaches the summit of the gas chamber, the gases alone will be forced to the surface by reason of the internal pressure, and not the slightest trace of petroleum will accompany them.

In No. 2, as the well ends at the side of the pocket, only a portion of the petroleum--that which is included between the dotted lines--will come to the surface.

In No. 3, as the well ends at the lowest extremity of the pocket, nearly the entire contents of the latter will be forced out naturally. It results from this that in petroleum exploitation the sudden appearance and disappearance of the spouting in no wise proves that the pocket is exhausted.--_Science et Nature_.

ALUMINUM AND ITS ALLOYS.

Symbol, Al. Equivalent, old, 13.7; new. 27.49. Specific gravity, cast, 2.46. Hammered, 2.67. Specific heat, 0.2143, Heat conductivity, 0.66 on silver scale = 100.

Melting point, 1,250° or 1,560° Fah., according to different authorities.

A shining, white, sonorous metal, having a shade between silver and platinum. It is malleable and ductile, does not oxidize when exposed to dry or moist air, and is not chemically affected by hot or cold water.

Sulphureted hydrogen gas, which so readily tarnishes silver, has no action upon this metal.

Having but one defect in its uses as a pure metal (difficulty in soldering), it enters largely as an alloy of other metals, making the baser metals more valuable in resisting oxidation, and as a good as well as cheap imitation of the precious metals.

Its power to ameliorate the condition of the alloys of copper, zinc, tin, iron, nickel, silver, gold, and platinum by portions sometimes less than a thousandth part is beautifully illustrated in the elegant articles of tableware, bric a brac, and ornamental hardware now coming upon the commercial market. Its uses in the mechanic arts in the various forms of bronzes in filling a long wanted requirement of combined ductility, strength, sonorousness, and freedom from oxidation, thus giving to its alloys a high value for articles of house hardware, carriage and harness trimmings, quick running machinery, journal bearings, propeller blades, and artillery. Piano wires made from its alloys will vibrate ten seconds longer than the best now in use.

For the kitchen and for articles for the toilet, there is no more beautiful and cleanly ware. An alloy of silver 20 and aluminum 80 parts by weight, for nautical and other instruments, is without a rival in beauty and lightness; the sea air does not tarnish it.

The aluminum-silver alloys are more valuable than pure silver for table service; its wares will not be destroyed by the constant polishing that wears out our plate, and holds an immunity from the destructive effects of the fatty and acetic acids.

For watch cases it wears cleaner than pure silver, and for watch movements it is far superior to the brass and nickel or German silver heretofore used. An alloy is now made in France that has elastic qualities equal to steel for watch springs, and with the valuable property of being free from magnetic effect.

The aluminum bronzes, when combined with five per cent. of gold, have all the beauty, finish, and durability of color of eighteen carat gold; they are entering largely into the manufacture of watch cases and jewelry.

The composition most approved is made of copper 85, aluminum 10, gold 5, parts by weight. This can be soldered with any of the jeweler's solders of gold, silver, and zinc in the usual way.

The most important alloy, _aluminum bronze_, is composed of aluminum 10 parts, copper 90 parts by weight; specific gravity, 7.7. It has a pale gold color, harder than ordinary bronze, takes a fine polish, is malleable and ductile, but when rolled into sheets requires annealing at every third passage through the rolls, and when drawn into wire must be frequently annealed. It may be forged cold or hot, and can be drawn in tubes. In wire it has a tensile strength of 100,000 lb.

This alloy is often found to be brittle at the first mixing, but becomes ductile after remelting. It is softened while being worked by plunging in water at a low red heat.

The Parisian gold colored alloy is made of aluminum 10.7, copper, 89.3, by weight; used much for cheap French jewelry.

A non-oxidizable alloy in a moist atmosphere: Aluminum, 25, iron 75 = 25 per cent. aluminum. A hard bright alloy, with the properties of silver: Silver 5 (by weight); aluminum 95 = 5 per cent. aluminum.

The silver alloys with aluminum bronze, as represented in the four following atomic formulas, are of a rich gold color, and well adapted for jewelry, watch cases, etc.:

Cu Al Ag
Ag + 24 (Al + Cu_{6}) = 0.9180 + 0.0616 + 0.0203
Ag + 24 (Al + Cu_{7}) = 0.9241 + 0.0570 + 0.0188
Ag + 24 (Al + Cu_{8}) = 0.9330 + 0.0504 + 0.0166
Ag + 24 (Al + Cu_{9}) = 0.9400 + 0.0450 + 0.0150

The figures being proportional weights.

A cheap alloy for journal boxes and machinery may be made by substituting zinc for silver in the following atomic proportions:

Cu Al Zn
Zn + 2(Al + Cu_{6}) = 0.8643 + 0.0622 + 0.0734
Zn + 2(Al + Cu_{9}) = 0.9053 + 0.0435 + 0.0512
Zn + 2(Al + Cu_{12}) = 0.9273 + 0.0333 + 0.0394

This is subject to considerable shrinkage in casting, but is tenacious, and when drawn into wire has a tensile strength of ninety to one hundred thousand pounds.

The following alloys, in which iron enters as a third element, are well adapted for gun metal, being hard, tenacious, laminable, and ductile:

Cu Al Fe
Fe + (Al + Cu_{15}) = 0.9203 + 0.0267 + 0.0530
Fe + (Al + Cu_{9}) = 0.9399 + 0.0446 + 0.0149

Also a four-element alloy of

Cu Al Zn Fe
1. Fe + Zn + (Al + Cu_{12}) = 0.8386 + 0.0305 + 0.0712 + 0.0600
2. Fe + Zn + (Al + Cu_{15}) = 0.8666 + 0.0249 + 0.0588 + 0.0496

The tensile strength of the above alloys as drawn wire is 82,000 pounds for the first, and 107,000 pounds for the second.

All of the alloys in which zinc or zinc and iron enter in place of silver, the color is affected and the luster diminished.

With nickel and platinum for the third element, we have:

Cu Al Ni
Ni + 6 (Al + Cu_{6}) = 0.9129 + 0.0634 + 0.0237
Pl + 21 (Al + Cu_{6}) = 0.9117 + 0.0656 + 0.0225

Those alloys into which platinum is introduced are less affected by acids than those in which silver takes the place of platinum; platinum producing a higher luster than silver.

In the alloys of aluminum bronze with the more difficultly fusible metals, it is preferable to fuse the bronze first, then add the other metal in small shavings or wire; by this means the less fusible metal absorbs the other without raising the heat of the furnace excessively. Add the least fusible metal last, a little at a time, allowing the heat of the melted metal to fall by degrees, which prevents boiling and evaporation. The crucibles for mixing the alloys should be of plumbago lined with a paste of lime.

Avoid sand crucibles, as silicium may be reduced and absorbed by the aluminum, inducing brittleness. If found brittle, remelt with cryolite as a flux, or stir the melted metal or alloy with a hard wood stick that has been slightly charred.

In adding aluminum to the copper, cut it in small pieces and push it to the bottom of the crucible with a dry, hard wood stick split so as to hold the pieces.

Sodium chloride (common salt) calcined to evaporate the water, and caustic soda with pulverized charcoal, may be used as a flux for pure aluminum. Avoid borax as a flux, as its metal may suffer reduction, making the aluminum brittle. Aluminum will alloy with tin alone, but is liable to separate on refusion. Does not alloy with lead.

Bismuth, even in minute quantity, makes these alloys brittle.

The East Indian steel called _wootz_ is, according to analysis, alloyed with aluminum. No reliable solder has yet been found for pure aluminum that will flow freely under the blow pipe or from a soldering iron.

A process recently adopted in France is to plate the parts to be united with alloys of tin 5, aluminum 1, upon which tin solder will flow. These proportions may be slightly varied to suit requirements for hardness.

Harder solders to be used with a blowpipe may be made with alloys of zinc, tin, and aluminum.

Aluminum is now made at the works of M. Deville, at Javelle, near Paris, and at Salindres, France; also at Birmingham, England. The product of late has reached the value of $20,000 annually in Europe. It has been claimed to be made in Philadelphia at a reduced cost. The present price in New York is $1.25 per oz. As its bulk is over four times as great as silver, its comparative cost is but one-third that of silver--a point not often considered when the price is quoted.

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TABLE OF CONTENTS.

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