Chapter X: TECHNOLOGY.--Apparatus for Testing Champagne Bottles and (3)

HONEY.--The simplest form of honey extractor (Pat. 61,216) consists of a square framework, symmetrical with respect to a vertical spindle. This framework is surrounded by a wire gauze. The combs, after having the heads of the cells cut off, are placed in comb-holders against the wire netting on the four sides, the cells pointing outward. The machine is turned by hand. The honey is hurled against the walls of a receiving case and caught below. But few improvements have been made on this. The latest machines are still hand-driven, as a sufficiently high velocity can be obtained in this manner. In one style the combs are placed upon a floor which rests upon springs. The rotating box is given a slight vertical and horizontal reciprocatory motion, by which the combs are made to grate on the wire gauze sides, breaking the cells and liberating the honey. Thus the labor of cutting the cells is saved. Every comb has two sides, and to present each side in succession to the outside without removing from the basket, several devices have been patented. In some the comb holders are hinged in the corners of the basket, and have an angular motion of ninety degrees. Decreasing the speed is sufficient to swing these. The other side is then emptied by revolving in the opposite direction. In one case each holder has a spindle of its own, connected with the main spindle by gearing and, to present opposite side, turns through 180°. The usual number of sides and hence of comb holders is four, but eight have been used. There are minor differences in details of construction, looking to the most convenient removal and insertion of comb, the reception of the extracted honey in cups, buckets, etc., and the best method of giving rapid rotation, which cannot be touched upon. The product of the operation is white and opaque, but upon heating regains its golden color and transparency.

STARCH.--A centrifugal to separate starch from triturated grain, carried in suspension in water, is as follows. (Pat. 273,127--Müller & Decastro.) The starch water is led to the bottom of a basket, and, as starch is heavier than the gluten with which it is mixed, the former will be immediately compacted against the periphery of the basket, lodging first in the lower corner, the starch and gluten forming two distinct strata. A tube with a cutting edge enters the compacted mass so deeply as to peel off the gluten and part of the starch, which is carried through the tube to another compartment of the basket, just above, where the same operation is performed, and so on. There may be only one compartment, the tube carrying the gluten directly out of the machine. These machines are continuous working, and hence some way must be devised to carry the water off. The inner surface of the water is, as we have seen, a cylinder. When the diameter of this cylinder becomes too small, overflow must be allowed. One plan is to have an overflow opening made in the bottom of the basket in such a way that as the starch wall thickens, the opening recedes toward the center. The starch wall is either lifted out in cakes or put again in suspension by spraying water on it and conducting the mixture off.

A centrifugal (Pat. 74,021) to separate liquids from paints depends on building a wall of paint on the sides of the basket and carrying the liquids off at the center.

A centrifugal (Pat. 310,469) for assorting wood pulp, paper pulp, etc., works by massing the constituents in two or three cylindrical strata, and after action severing and removing these separately.

BREWING.--In brewing, centrifugals are quite useful. After the wort has been boiled with hops, albuminous matters are precipitated by the tannic acid, which must be extracted. Besides these the mixture frequently contains husk, fiber, and gluten. The machine (Pat. 315,876), although quite unique in construction, has the same principle of working as a sugar centrifugal, and need not be described. There is one point, however, which might be noticed--that air is introduced at about the same point as the material, and has an oxidizing and refrigerating effect.

Class I. includes also centrifugals for the following purposes: The removal of must from the grape after crushing, making butter, extracting oils from solid fats, separating the liquid and solid parts of sewerage, drying hides, skins, spent tan and the like, drying coils of wire.

HORIZONTAL CENTRIFUGALS.--Only vertical machines have been and will be dealt with. Horizontal centrifugals, that is, those whose spindles are horizontal have been made, but the great inconvenience of charging and discharging connected with them has occasioned their disuse; though in other respects for liquids they are quite as good as vertical separators. Their underlying theory is practically the same as that hereinbefore discussed.

CLASS II., CREAMERS.--Centrifugals of the second class separate liquids from liquids. There are two main applications in this class--to separate cream from milk and fusel oil from alcoholic liquors. When a liquid is to be separated from a liquid, the receptacle must be imperforate. The components of different specific gravity become arranged in distinct concentric cylindrical strata in the basket, and must be conducted away separately. In creamers the particles of cream must not be broken or subjected to any concussion, as partial churning is caused and the cream will, in consequence, sour more rapidly.

The chief cause of oscillations in machines of this class, where the charge is liquid, is the waves which form on the inner surface. They may be met by allowing a slight overflow over the inner edge of the rim of the basket; or by having either horizontal partitions, or vertical, radial ones, special cases of which will be noticed. Oscillations may also be met in the same manner as in sugar machines, by allowing the revolving parts to revolve about an axis through their common center of gravity. (Pat. 360,342--J. Evans.)

The crudest form of creamer contains a number of bottles, with their necks all directed toward the spindle, filled with milk. The necks, in which the cream collects, are graduated to tell when the operation is complete.

Many methods for introducing the milk into creamers have been devised. It may run in from the top at the center, or emerge from a pipe at the bottom of the basket; or the spindle may be hollow and the milk sucked up through it from a basin below. It is usual to let the milk enter under hydrostatic pressure (Pat. 239,900--D. M. Weston) and let the force of expulsion of the cream be dependent on this pressure. This renders the escape quiet, and prevents churning. Gravity, too, is made effective in carrying the constituents off.

The cream may escape through a passage in the bottom at the center, and the skim milk at the lower outer corner; or by ingeniously managed passages both may escape at or near center. The rate of discharge can be managed by regulating the size of opening of exit passages.

A curious method consists in having discharge pipes provided with valves and floats at their lower ends, dipping into the liquid (Pat. 240,175). "The valves are opened and closed, or partially opened or closed, by the floats attached to them, these floats being so constructed and arranged with reference to their specific gravity and the specific gravity of the component parts of the liquids operated upon, that they will permit only a liquid of a determinate specific gravity to escape through the pipes to which they are respectively attached."

We may have tubes directed into the different strata with cutting edges. (Pat. 288,782.) A remarkable fact noticed in their use is that these edges wear as rapidly as if solids were cut instead of liquids.

The separated fluids may be received into recessed rings, having discharge pipes, the proportionate quantity discharged being regulated by the proximity of the discharge lips to the surface of the ring, and the centrifugal force being availed of to project the liquids through the discharge pipes.

There is a very simple device by which a very rapid circulation of the liquid is brought about. (Pat. 358,587--C.A. Backstrom.) The basket has radial vertical partitions, all but one having communicating holes, alternately in upper and lower corners. The milk is delivered into the basket on one side of this imperforate partition and must travel the whole circuit of the basket through these communicating holes, until it reaches the partition again, and then passes into a discharge pipe. Thus during this long course every particle of cream escapes to the center. As the holes are close to the walls of the basket, the cream has not the undulatory motion of the milk, which would injure it. The greater the number of partitions, the longer is the travel of the milk, and the more rapid the circulation. Blades have been devised similar to the above, having communicating passages extending the whole width of the blade, but we see that here the cream would circulate with the milk; which must not be allowed. Curved blades have been used, and paddles and stirrers, to set the milk in motion, but to them the same objection may be made.

Fig. 30 (Pat. 355,048--C.A. Backstrom) illustrates one of the latest and best styles of creamers. The milk enters at C. The skim milk passes into tube, T, and the cream goes to the center and passes out of the openings in the bottom, _k^{l}_, _k^{2}_, and _k^{3}_, out of the slit, k, and thence out through D^{5}. The skim milk moves through T, becoming more thoroughly separated all the while, and at each of the radial branch tubes, T^{1}, T^{2}, T^{3}, and T^{4}, some cream leaves it and goes to the center, while it passes down out of slit, t^{3}, and thence out of D^{6}.

Fig. 31 (Pat. 355,050--C.A. Backstrom) shows another very late style of creamer. A pipe delivers the milk into P^{4}. Passing out of the tube separation takes place, and cream falls down the center to P^{2} and out of O^{3}. When the compartment under the first shelf becomes full of the skim milk, the latter passes up through the slot, S, strikes a radial partition, R, and its course is reversed. Here more cream separates and passes to center and falls directly, and so on through the whole series of annular compartments, until the top one, when the skim milk enters tube T^{2} and passes out of O^{2}. By this operation there are substantially repeated subjections of specified quantities of milk to the action of centrifugal force, bringing about a thorough separation. By changing the course of the milk in direction, its path is made longer. This machine can run at much lower speed than many other styles, and yet do the same work.

CLASS III., SOLIDS FROM SOLIDS.--As for grain machines, which are in this class, it may be said that in centrifugal flour bolters, bran cleaners, and middlings purifiers, though theoretically centrifugal force plays an important part in their action, yet practically the real separation is brought about by other agencies: in some by brushes which rub the finer particles through wire netting as they rotate against it.

The principle exhibited in a separator of grains and seeds is very neat. (Pat. 167,297.) See Fig. 32. That part of the machine with which we have to do consists essentially of a horizontal revolving disk. The mixed grains are cast on this disk, pass to the edge, and are hurled off at a tangent. Suppose at A. Each particle is immediately acted on by three forces. For all particles of the same size and having the same velocity the resistance of the air may be taken the same, that is, proportional to the area presented. The acceleration of gravity is the same; but the inertia of the heavier grain is greater. The resultant of the two conspiring forces R and (M_v_^{2})/2 varies, and is greater for a heavier grain. Therefore, the paths described in the air will vary, especially in length; and how this is utilized the drawing illustrates.

ORE.--In ore machines there is one for pulverizing and separating coal (Pat. 306,544), in which there is a breaker provided with helical blades or paddles, partaking of rapid rotary motion within a stationary cylinder of wire netting. The dust, constituting the valuable part of the product, is hurled out as fast as formed. In this style of machine, beaters are necessary not only for pulverizing, but to get up rotary motion for generating centrifugal force. In the classes preceding, the friction of the basket sufficed for this latter purpose; but here there is no rotating basket and no definite charge. As the material falls through the machine, separation takes place. Various kinds of ore may be treated in the same manner.

An "ore concentrator" (Pat. 254,123), as it is called, consists of a pan having rotary and oscillatory motions. Crushed ore is delivered over the edge in water. The heavy particles of the metal are thrown by centrifugal force against the rim of the pan, overcoming the force of the water, which carries the sand and other impurities in toward the center and away.

AMALGAMATORS.--The best ore centrifugal or separator is what is called an "amalgamator." The last invention (Pat. 355,958, White) consists essentially of a pan, a meridian section of which would give a curve whose normal at any point is in the direction of the resultant of the centrifugal force at that point and gravity. There is a cover to this pan whose convexity almost fits the concavity of the pan, leaving a space of about an inch between. Crushed ore with water is admitted at the center between the cover and the pan, and is driven by centrifugal force through a mass of mercury (which occupies part of this space between the two) and out over the edge of the pan. The particles of metal coming in contact with the mercury amalgamate, and as the speed is regulated so that it is never great enough to hurl the mercury out, nothing but sand, water, etc., escape. There have been many different constructions devised, but this general principle runs through all. By having annular flanges running down from the cover with openings placed alternately, the mixture is compelled to follow a tortuous course, thus giving time for all the gold or other metal to become amalgamated. There are ridges in the pan, too, against which the amalgam lodges. It is claimed for this machine that not a particle of the precious metal is lost, and experiments seem to uphold the claim.

A machine for separating fine from coarse clay for porcelain or for separating the finer quality of plumbago from the coarser for lead pencils uses an imperforate basket, against the wall of which the coarser part banks and catches under the rim. The finer part forms an inner cylindrical stratum, but is allowed to spill over the edge of the rim. The mixture is introduced at the bottom of the basket at the center.

CLASS IV., GASES AND SOLIDS.--There is a very simple contrivance illustrating machines of this class used to free air from dust or other heavy solid impurities which may be in suspension. See Fig. 33. The air enters the passage, B (if it has no considerable velocity of itself, it must be forced in), forms a whirlpool in the conically shaped receptable, A, and passes up out of the passage, D. The heavy particles are thrown on the sides and collect there and fall through opening, C, into some closed receiver.

CLASS V., GASES AND LIQUIDS.--The occluded gases in steel and other metal castings, if not separated, render the castings more or less porous. This separation is effected by subjecting the molten metal to the action of centrifugal force under exclusion of air, producing not only the most minute division of the particles, but also a vacuum, both favorable conditions for obtaining a dense metal casting.

Most of the devices for drying steam come under this head. Such are those in which the steam with the water in suspension is forced to take a circular path, by which the water is hurled by centrifugal force against the concave side of the passage and passes back to the water in the boiler.

SPEED.--The centrifugal force of a revolving particle varies, as we have seen, as the square of the angular velocity, so that the effort has been to obtain as high a number of revolutions per minute as was consistent with safety and with the principle of the machine. For example, creamers which are small and light make 4,000 revolutions per minute, though the latest styles run much more slowly. Driers and sugar machines vary from 600 to 2,000, while on the other hand the necessity of keeping the mercury from hurling off in an amalgamator prevents its turning more rapidly than sixty or eighty times a minute.

However, speed in another sense, the speed with which the operation is performed, is what especially characterizes centrifugal extractors. In this particular a contrast between the old methods and the new is impressive. Under the action of gravity, cream rises to the milk's surface, but compare the hours necessary for this to the almost instantaneous separation in a centrifugal creamer. The sugar manufacturer trusted to gravity to drain the sirup from his crystals, but the operation was long and at best imperfect. An average sugar centrifugal will separate 600 pounds of magma perfectly in three minutes. Gold quartz which formerly could not pay for its mining is now making its owners' fortunes. It is boasted by a Southern company that whereas they were by old methods making twenty-five _cents_ per ton of gold quartz, they now by the use of the latest amalgamator make twenty-five _dollars_. Centrifugal force, as applied in extractors, has opened up new industries and enlarged old ones, has lowered prices and added to our comforts, and centrifugal extractors may well command, as they do, the admiration of all as wonderful examples of the way in which this busy age economizes time.

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A NEW TYPE OF RAILWAY CAR.

Figs. 1 and 2 give a perspective view and plan of a new style of car recently adopted by the Bone-Guelma Railroad Company, and which has isolated compartments opening upon a lateral passageway. In this arrangement, which is due to Mr. Desgranges, the lateral passageway does not extend all along one side of the car, but passes through the center of the latter and then runs along the opposite side so as to form a letter S. The car consists in reality of two boxes connected beneath the transverse passageway, but having a continuous roof and flooring. The two ends are provided with platforms that are reached by means of steps, and that permit one to enter the corresponding half of the car or to pass on to the next. The length from end to end is 33 feet in the mixed cars, comprising two first-class and four second-class compartments, and 32 feet in cars of the third class, with six compartments. The width of the compartments is 5.6 and 5 feet, according to the class. The passageway is 28 inches in width in the mixed cars, and 24 in those of the third class. The roof is so arranged as to afford a circulation of cool air in the interior.

The application of the zigzag passageway has the inconvenience of slightly elongating the car, but it is advantageous to the passengers, who can thus enjoy a view of the landscape on both sides of the train.--_La Nature._

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FOUNDATIONS OF THE CENTRAL VIADUCT OF CLEVELAND, O.

The Central viaduct, now under construction in the city of Cleveland, is probably the longest structure of the kind devoted entirely to street traffic. The superstructure is in two distinct portions, separated by a point of high ground. The main portion, extending across the river valley from Hill street to Jennings avenue, is 2,840 feet long on the floor line, including the river bridge, a swing 233 feet in length; the other portion, crossing Walworth run from Davidson street to Abbey street, is 1,093 feet long. Add to these the earthwork and masonry approaches, 1,415 feet long, and we have a total length of 5,348 feet. The width of roadway is 40 feet, sidewalks 8 feet each. The elevation of the roadway above the water level at the river crossing is 102 feet. The superstructure is of wrought iron, mainly trapezoidal trusses, varying in length from 45 feet to 150 feet. The river piers are of first-class masonry, on pile and timber foundations. The other supports of the viaduct are wrought iron trestles on masonry piers, resting on broad concrete foundations. The pressure on the material beneath the concrete, which is plastic blue clay of varying degrees of stiffness mixed with fine sand, is about one ton per square foot.

The Cuyahoga valley, which the viaduct crosses from bluff to bluff, is composed mainly of blue clay to a depth of over 150 feet below the river level. No attempt is made to carry the foundation to the rock. White oak piles from 50 to 60 feet in length and 10 inches in diameter at small end are driven for the bridge piers either side of the river bed, and these are cut off with a circular saw 18 feet below the surface of the water. Excavation by dredging was made to a depth of 3 feet below where the piles are cut off to allow for the rising of the clay during the driving of the piles. The piles are spaced about 2 feet 5 inches each way, center to center. The grillage or platform covering the piles consists of 14 courses of white oak timber, 12 inches by 12 inches, having a few pine timbers interspersed so as to allow the mass to float during construction. The lower half of the platform was built on shore, care being taken to keep the lower surface of the mass of timber out of wind. The upper and lower surfaces of each timber were dressed in a Daniels planer, and all pieces in the same course were brought to a uniform thickness. The timbers in adjacent courses are at right angles to each other. The lower course is about 58 feet by 22 feet, the top course about 50 by 24 feet, thus allowing four steps of one foot each all around. The first course of masonry is 48 feet by 21 feet 8 inches; the first course of battered work is 41 feet 8½ inches by 16 feet 3 inches. Thus the area of the platform on the piles is 1,856 square feet, and of the first batter course of masonry 777.6 square feet, or in the ratio of 2.4 to 1. The height of the masonry is 78 feet above the timber, or 73½ feet above the water. The number of piles in each foundation is 312. The average load per pile is about 11 tons, and the estimated pressure per square inch of the timber on the heads of the piles is about 200 pounds.

To prevent the submersion of the lower courses of masonry during construction, temporary sides of timber were drift-bolted to the margin of the upper course of the timber platform, and carried high enough to be above the surface of the water when the platform was sunk to the head of the piles by the increasing weight of masonry.

The center pier is octagonal, and is built in the same general manner as to foundations as the shore piers, but the piles are cut off 22 feet below water, and there are eighteen courses of timber in the grillage. The diameter of the platform between parallel sides is 53 feet, while that of the lower course of battered masonry is but 37 feet. The areas are as 2,332 to 1,147, or as 2 to 1 nearly. The pressure per square inch of timber on the heads of the piles is about the same as stated above for the shore piers. The number of piles under the center pier is 483.

The risks and delays by this method of constructing the foundations were much less, and the cost also, than if an ordinary coffer dam had been used. Also the total weight of the piers is much less, as that portion below a point about two feet below the water adds nothing to their weight.

The piles were driven with a Cram steam hammer weighing two tons, in a frame weighing also two tons. The iron frame rests directly upon the head of the pile and goes down with it. The fall of the hammer is about 40 inches before striking the pile. The total penetration of the piles into the clay averaged 27 feet. The settlement of the pile during the final strokes of the hammer varied from one quarter to three quarters of an inch per blow.

There are 122 masonry pedestals, of which eight are large and heavy, carrying spans of considerable length. They will all be built upon concrete beds, except a few near the river on the north side, where piles are required.

The four abutments with their retaining walls are of first-class rock-faced masonry. The footing courses are stepped out liberally, so as to present an unusually large bottom surface. They rest on beds of concrete 4 feet thick. The foundation pits are about 50 feet below the top of the bluffs, and are in a material common to the Cleveland plateau, a mixture of blue sand and clay, with some water. The estimated load of masonry on the earth at the bottom of the concrete is one and seven tenths tons to the square foot. Two of the large abutments were completed last season. They show an average settlement of three eighths of an inch since the lower footing courses were laid.

The facts and figures here given regarding the viaduct were kindly furnished by the city civil engineer, C.G. Force, who has the work in charge.--_Jour. Asso. of Eng. Societies._

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For sticking paper to zinc, use starch paste with which a little Venice turpentine has been incorporated, or else use a dilute solution of white gelatine or isinglass.

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CENTRIFUGAL PUMPS AT MARE ISLAND NAVY YARD, CALIFORNIA.[1]

[Footnote 1: Built by the Southwark Foundry and Machine Company,
of Philadelphia.]

By H.R. CORNELIUS.

In December, 1883, bids were asked for by the United States government on pumping machinery, to remove the water from a dry dock for vessels of large size.

The dimensions of the dock, which is situated on San Pablo Bay, directly opposite the city of Vallejo, are as follows:

Five hundred and twenty-nine feet wide at its widest part, 36 feet deep, with a capacity at mean tide of 9,000,000 gallons.

After receiving the contract, several different sizes of pumps were considered, but the following dimensions were finally chosen: Two 42 inch centrifugal pumps, with runner 66 inches in diameter and discharge pipes 42 inches, each driven direct by a vertical engine with 28 inch diameter cylinder and 24 inch stroke.

These were completed and shipped in June, 1885, on nine cars, constituting a special train, which arrived safely at its destination in the short space of two weeks, and the pumps were there erected on foundations prepared by the government.

From the "Report of the Chief of Bureau of Yards and Docks" I quote the following account of the official tests:

"The board appointed to make the test resolved to fill the
dock to about the level that would attain in actual service
with a naval ship of second rate in the dock, and the tide at
a stage which would give the minimum pumping necessary to
free the dock. The level of the 20th altar was considered as
the proper point, and the water was admitted through two of
the gates of the caisson until this level was reached; they
were then closed. The contents of the dock at this point is
5,963,921 gallons.

"The trial was commenced and continued to completion without
any interruption in a very satisfactory manner.

"In the separate trials had of each pump, the average
discharge per minute was taken of the whole process, and
there was a singular uniformity throughout with equal piston
speed of the engine.

"It was to be expected, and in a measure realized, that
during the first moments of the operations, when the level of
the water in the dock was above the center of the runner of
the pumps, that the discharge would be proportioned to the
work done, where no effort was necessary to maintain a free
and full flow through the suction pipes; but as the level
passed lower and farther away from the center there was no
apparent diminution of the flow, and no noticeable addition
to the load imposed on the engine. The variation in piston
speed, noted during the trial, was probably due to the
variation of the boiler pressure, as it was difficult to
preserve an equal pressure, as it rose in spite of great
care, owing to the powerful draught and easy steaming
qualities of the boilers.

"After the trial of the second pump had been completed the
dock was again filled through the caisson, and as both pumps
were to be tried, the water was admitted to a level with the
23d altar, containing 7,317,779 gallons, which was seven feet
above the center of the pumps; this was in favor of the pumps
for the reasons before stated. In this case all the boilers
were used.

"Everything moved most admirably, and the performance of
these immense machines was almost startling. By watching the
water in the dock it could be seen to lower bodily, and so
rapidly that it could be detected by the eye without
reference to any fixed point.

"The well which communicates with the suction tunnel was
open, and the water would rise and fall, full of rapid swirls
and eddies, though far above the entrance of these tunnels.
Through the man hole in the discharge culvert the issuance
from the pipes could be seen, and its volume was beyond
conception. It flowed rapidly through the culvert, and its
outfall was a solid prism of water, the full size of the
tunnel, projecting far into the river.

"During a pumping period of 55 minutes, the dock had been
emptied from the twenty-third to two inches above the sixth
altar, containing 6,210,698 gallons, an average throughout of
112,922 gallons per minute. At one time, when the revolutions
were increased to 160 per minute, the discharge was 137,797
gallons per minute. This is almost a river, and is hardly
conceivable. After the pumps were stopped, on this occasion,
tests were made with each in succession as to the power of
the ejectors with which each is fitted to recharge the pumps.

"The valves in the discharge pipe were closed and steam
admitted to the ejector, the pump being still and no water in
the gauge glass on the pump casing, which must be full before
the pumps will work. The suction pipe of the ejector is only
two and a half inches in diameter, the steam pipe one inch in
diameter. To fully charge the pumps at this point required
filling the pump casing and the suction pipe containing about
2,000 gallons; this was accomplished in four minutes, and
when the gauge glass was full the pump operated instantly and
with certainty, discharging its full volume of water.

"I went on several occasions down in the valve pits on the
ladder of the casing, and to all accessible parts while in
motion at its highest speed, and there was no undue
vibration, only a uniform murmur of well-balanced parts, and
the peculiar clash of water against the sides of the casing
as its velocity was checked by the blank spaces in the
runner.

"The pumps are noisy while at work, due to the clashing of
the water just mentioned, but it affords a means of detecting
any faulty arrangements of the runner or unequal discharge
from any of its openings. While moving at a uniform speed,
this clashing has a tone whose pitch corresponds with that
velocity of discharge, and if this tone is lacking in
quality, or at all confused, there is want of equality of
discharge through the various openings of the runner. To this
part I gave close attention, and there was nothing that the
ear could detect to indicate aught but the nicest adjustment.
The bearings of the runners worked with great smoothness, and
did not become at all heated. Through a simple, novel
arrangement, these bearings are lubricated and kept cool.
There is a constant circulation of water from the pumps by
means of a small pipe, which completes a circuit to an
annular in the bearings back to the discharge pipe while the
pump is in motion, requiring no oil and making it seemingly
impossible to heat these bearings.

"The large cast steel valves placed in the embouchement of
the casing, it was thought, might act to check the free
discharge, and arrangements were provided for raising and
keeping them open by a long lever key attached to their axes
of revolution, but, to our great surprise, at the first gush
from the pumps these valves, weighing nearly 1,500 pounds,
were lifted into their recessed chambers, giving an
unobstructed opening to the flow, and they floated on its
surface unsupported, save by the swiftly flowing water,
without a movement, while the pump was in operation.

"The steam-actuated valves in the suction and discharge pipes
worked very well, and the water cushion gave a slow, uniform
motion, and without shock, either in opening or closing them.

"The engines worked noiselessly, without shock or labor. At
no time during the trial was the throttle valve open more
than three-eighths of an inch.

"The indicator cards taken at various intervals gave 796
horse power, and the revolutions did not exceed 160 at any
time, though it was estimated that 900 horse power and 210
revolutions would be necessary to attain the requisite
delivery. So that there is a large reserve of power available
at any time.

"The erection of this massive machinery has been admirably
done. The parts, as sent from the shops of the contractor,
have matched in all cases without interference here; and,
when lowered into place, its final adjustment was then made
without the use of chisel or file, and has never been touched
since.

"The joints of the steam and water connections were perfect,
and the method of concentrating all valves, waste pipes, and
important movements at the post of the engineer in charge
gives him complete control of the whole system of each engine
and pump without leaving his place, and reduces to a minimum
the necessary attendance. All the parts are strong and of
excellent design and workmanship; simple, and without
ornamentation.

"Looking down upon them from a level of the pump house
gallery, they are impressive and massive in their simplicity.

"The government is well worth of congratulation in possessing
the largest pumping machinery of this type and of the
greatest capacity in the world, and the contractors have
reason to be proud of their work."--_Proc. Eng. Club._

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THE PART THAT ELECTRICITY PLAYS IN CRYSTALLIZATION.

Since the discovery of the multiplying galvanometer, we know for an absolute certainty that in every chemical action there is a production of electricity in a more or less notable quantity, according to the nature of the bodies in presence. Though, in the play of _affinity_, there is a manifestation of electricity, is it the same with _cohesion_, which also is a chemical force?

We know, on another hand, that, on causing electricity to intervene, we bring about the crystallization of a large number of substances. But is the converse true? Is spontaneous crystallization accompanied with an appreciable manifestation of electricity? If we consult the annals of science and works treating on electricity in regard to this subject, we find very few examples and experiments proper to elucidate the question.

Mr. Mascart is content to say: "Some experiments seem to indicate that the solidification of a body produces electricity." Mr. Becquerel does more than doubt--he denies: "As regards the disengagement of electricity in the changing of the state of bodies, we find none." This assertion is too sweeping, for further along we shall cite facts that prove, on the contrary, that in the phenomena of crystallization (to speak of this change of state only) there is an unequivocal production of electricity. Let us remark, in the first place, that when a number of phenomena of physical and chemical order incontestably testify to the very intimate correlation that exists between the molecular motions of bodies and their electrical state, it would not be very logical to grant that electricity is absent in crystallization.

Thus, to select an example from among physical effects, the vibratory phenomena that occur in telephone transmissions, under the influence of a very feeble electric current, show us that the molecular constitution of a solid body is extremely variable, although within slight limits. The feeblest modification in the electric current may be shown by molecular motions capable of propagating themselves to considerable distances in the conducting wire. Conversely, it is logical to suppose that a modification in the molecular state of a body must bring electricity into play. If, in the phenomena of solidification, and particularly of crystallization, we collect but small quantities of electricity, that may be due to the fact that, under the experimental conditions involved, the electricity is more or less completely absorbed by the work of crystal building.

On another hand, the behavior of electricity shows in advance the multiple role that this agent may play in the various physical, chemical, and mechanical phenomena.

There is no doubt that electricity exists immovable or in circulation everywhere, latent or imperceptible, around us, and within ourselves, and that it enters as a cause into the majority of the chemical, physical, and mechanical phenomena that are constantly taking place before our eyes. A body cannot change state, nature, temperature, form, or place, even, without electricity being brought into play, and without its accompanying such modifications, if it presides therein. Like heat, it is _the_ natural agent _par excellence_; it is the invisible and ever present force which, in the ultimate particles of matter, causes those motions, vibrations, and rotations that have the effect of changing the properties of bodies. Upon entering their intimate structure, it orients or groups their atoms, and separates their molecules or brings them together. From this, would it not be surprising if it did not intervene in the wonderful phenomenon of crystallization? Crystallization, in fact, depends upon _cohesion_, and, in the thermic theory, this force is not distinct from affinity, just as solution and dissociation are not distinct from combination.

On this occasion, it is necessary to say that, between affinity, heat, and electricity there is such a correlation, such a dependency, that physicists have endeavored to reduce to one single principle all the causes that are now distinct. The mechanical theory of heat has made a great stride in this direction.

The equivalence of the thermic, mechanical and chemical forces has been demonstrated; the only question hereafter will be to select from among such forces the one that must be adopted as the sole principle, in order to account for all the phenomena that depend upon these causes of various orders. But in the present state of science, it is not yet possible to explain completely by heat or electricity, taken isolatedly, all the effects dependent upon the causes just mentioned. We must confine ourselves for the present to a study of the relations that exist between the principal natural forces--affinity, molecular forces, heat, electricity, and light. But from the mutual dependence of such forces, it is admitted that, in every natural phenomenon, there is a more or less apparent simultaneous concurrence of these causes.

In order to explain electric or magnetic phenomena, and also those of crystallization, it is admitted that the atoms of which bodies are composed are surrounded, each of them, with a sort of atmosphere formed of electric currents, owing to which these atoms are attracted or repelled on certain sides, and produce those varied effects that we observe under different circumstances. According to this theory, then, atoms would be small electro-magnets behaving like genuine magnets. Entirely free in gases, but less so in liquids and still less so in solids, they are nevertheless capable of arranging themselves and of becoming polarized in a regular order, special to each kind of atom, in order to produce crystals of geometrical form characteristic of each species. Thus, as Mr. Saigey remarks in "Physique Moderne" (p. 181): "So long as the atmospheres of the molecules do not touch each other, no trace of cohesion manifests itself; but as soon as they come together force is born. We understand why the temperatures of fusion and solidification are fixed for the same body. Such effects occur at the precise moment at which these atmospheres, which are variable with the temperature, have reached the desired diameter."

Although the phenomenon of crystallization does not essentially depend upon temperature, but rather upon the relative quantity of liquid that holds the substance in solution, it will be conceived that a moment will arrive when, the liquid having evaporated, the atmospheres will be close enough to each other to attract each other and become polarized and symmetrically juxtaposed, and, in a word, to crystallize.

Before giving examples of the production of electricity in the phenomenon of crystallization, it will be well to examine, beforehand, the different circumstances under which electricity acts as the determining cause of crystallization or intervenes among the causes that bring about the phenomenon. In the first place, two words concerning crystallization itself: We know that crystallization is the passage, or rather the result of the passage, of a body from a liquid or gaseous state to a solid one. It occurs when the substance has lost its cohesion through any cause whatever, and when, such cause ceasing to act, the body slowly returns to a solid state.

Under such circumstances, it may take on regular, geometrical forms called crystalline. Such conditions are brought about by different processes--fusion, volatilization, solution, the dry way, wet way, and electric way. Further along, we shall give some examples of the last named means.

Let us add that crystallization may be regarded as a general property of bodies, for the majority of substances are capable of crystallizing. Although certain bodies seem to be amorphous at first sight, it is only necessary to examine their fracture with a lens or microscope to see that they are formed of a large number of small juxtaposed crystals. Many amorphous precipitates become crystalline in the long run.

In the examination of the various crystallizations that occupy us, we shall distinguish the following: (1) Those that are produced through the direct intervention of the electric current; (2) those in which electricity is manifestly produced by small voltaic couples resulting from the presence of two different metals in the solution experimented with; (3) those in which there are no voltaic couples, but in which it is proved that electricity is one of the causes that concur in the production of the phenomenon; (4) finally, those in which it is rational, through analogy with the preceding, to infer that electricity is not absent from the phenomenon.

I. We know that, by means of voltaic electricity or induction, we can crystallize a large number of substances.

Despretz tried this means for months at a time upon carbon, either by using the electricity from a Ruhmkorff coil or the current from a weak Daniell's battery. In both cases, he obtained on the platinum wires a black powder, in which were found very small octohedral crystals, having the property of polishing rubies rapidly and perfectly--a property characteristic of diamonds.

The use of voltaic apparatus of high tension has allowed Mr. Cross to form a large number of mineral substances artificially, and among these we may mention carbonate of lime, arragonite, quartz, arseniate of copper, crystalline sulphur, etc.

As regards products formed with the concurrence of electricity (oxides, sulphides, chlorides, iodides, etc.), see "Des Forces Physico-Chimiques," by Becquerel (p. 231).

There is no doubt as to the part played by electricity in the chemical effects of electro-metallurgy, but it will not prove useless for our subject to remark that when, in this operation, the current has become too weak, the deposit of metal, instead of forming in a thin, adherent, and uniform layer, sometimes occurs under the form of protuberances and crystalline, brittle nodules. When, on the contrary, the current is very strong, the deposit is pulverulent, that is, in a confused crystallization or in an amorphous state.

Further along, we shall find an application of this remark. We obtain, moreover, all the intermediate effects of cohesion, form, and color of galvanic deposits.

When, into a solution of acetate of lead, we pass a current through two platinum electrodes, we observe the formation, at the negative pole, of numerous arborizations of metallic lead that grow under the observer's eye (Fig. 1). The phenomenon is of a most interesting character when, by means of solar or electric light, we project these brilliant vegetations on a screen. One might believe that he was witness of the rapid growth of a plant (Fig. 2). The same phenomenon occurs none the less brilliantly with a solution of nitrate of silver. A large number of saline solutions are adapted to these decompositions, in which the metal is laid bare under a crystalline form. Further along we shall see another means of producing analogous ramifications, without the direct use of the electric current.--_C. Decharme, in La Lumiere Electrique._

* * * * *

ELECTRIC TIME.

By M. LIPPMANN.

The unit of time universally adopted, the second, undergoes only very slow secular variations, and can be determined with a precision and an ease which compel its employment. Still it is true that the second is an arbitrary and a variable unit--arbitrary, in as far as it has no relation with the properties of matter, with physical constants; variable, since the duration of the diurnal movement undergoes causes of secular perturbation, some of which, such as the friction of the tides, are not as yet calculable.

We may ask if it is possible to define an absolutely invariable unit of time; it would be desirable to determine with sufficient precision, if only once in a century, the relation of the second to such a unit, so that we might verify the variations of the second indirectly and independently of any astronomical hypothesis.

Now, the study of certain electrical phenomena furnishes a unit of time which is absolutely invariable, as this magnitude is a specific constant. Let us consider a conductive substance which may always be found identical with itself, and to fix our ideas let us choose mercury, taken at the temperature of 0° C., which completely fulfills this condition. We may determine by several methods the specific electric resistance, [rho], of mercury in absolute electrostatic units; [rho] is a specific property of mercury, and is consequently a magnitude absolutely invariable. Moreover, [rho] is _an interval of time_. We might, therefore, take [rho] as a unit of time, unless we prefer to consider this value as an imperishable standard of time.

In fact, [rho] is not simply a quantity the measure of which is found to be in relation with the measure of time. It is a concrete interval of time, disregarding every convention established with reference to measures and every selection of unit. It may at first sight, appear singular that an interval of time is found in a manner hidden under the designation _electric resistance_. But we need merely call to mind that in the electrostatic system the intensities of the current are speeds of efflux and that the resistances are times, i.e., the times necessary for the efflux of the electricity under given conditions. We must, in particular, remember what is meant by the specific resistance, [rho] of mercury in the electrostatic system. If we consider a circuit having a resistance equal to that of a cube of mercury, the side of which = the unit of length, the circuit being submitted to an electromotive force equal to unity, this circuit will take a given time to be traversed by the unit quantity of electricity, and this time is precisely [rho]. It must be remarked that the selection of the unit of length, like that of the unit of mass, is indifferent, for the different units brought here into play depend on it in such a manner that [rho] is not affected.

It is now required to bring this definition experimentally into action, i.e., to realize an interval of time which may be a known multiple of [rho]. This problem may be solved in various ways,[1] and especially by means of the following apparatus.

[Footnote 1: In this system the measurement of time is not
effected, as ordinarily, by observing the movements of a
material system, but by experiments of equilibrium. All the
parts of the apparatus remain immovable, the electricity alone
being in motion. Such appliances are in a manner clepsydræ. This
analogy with the clepsydræ will be perceived if we consider the
form of the following experiment: Two immovable metallic plates
constitute the armatures of a charged condenser, and attract
each other with a force, F. If the plates are insulated, these
charges remain constant, as well as the force, F. If, on the
contrary, we connect the armatures of resistance, R, their
charges diminish and the force, F, becomes a function of the
time, _t_; the time, _t_, inversely becomes a function of P. We
find _t_ by the following formula:

t = [rho] × (lS / S[pi]es) × log hyp(F0/F)

F0 and F being the values of the force at the beginning and
at the end of the time, _t_. The above formula is independent of
the choice of units. If we wish _t_ to be expressed in seconds,
we must give [rho] the corresponding value ([rho] = 1.058 X
10^-16). If we take [rho] as a unit we make [rho] = 1, and we
find the absolute value of the time by the expression:

(lS) / (8[pi]es) log hyp(F0/F)

We remark that this expression of time contains only abstract
numbers, being independent of the choice of the units of length
and force. S and _e_ denote surface and the thickness of the
condenser; _s_ and _l_ the section and the length of a column of
mercury of the resistance, R. This form of apparatus enables us
practically to measure the notable values of _t_ only if the
value of the resistance, R, is enormous, the arrangement
described in the text has not the same inconvenience.]

A battery of an arbitrary electromotive force, E, actuates at the same time the two antagonistic circuits of a differential galvanometer. In the first circuit, which has a resistance, R, the battery sends a continuous current of the intensity, I; in the second circuit the battery sends a discontinuous series of discharges, obtained by charging periodically by means of the battery a condenser of the capacity, C, which is then discharged through this second circuit. The needle of the galvanometer remains in equilibrium if the two currents yield equal quantities of electricity during one and the same time, [tau].

Let us suppose this condition of equilibrium realized and the needle remaining motionless at zero; it is easy to write the conditions of equilibrium. During the time, [tau], the continuous current yields a E quantity of electricity = -- [tau]; on the other hand, each charge of R the condenser = CE, and during the time, [tau], the number of [tau] discharges = -----, t being the fixed time between two discharges; t [tau] and t are here supposed to be expressed by the aid of an arbitrary unit of time; the second circuit yields, therefore, a [tau] quantity of electricity equal to CE × -----. The condition of t E [tau] equilibrium is then ---[tau] = CE × ----- ; or, more simply, t = CR. R t C and R are known in absolute values, i.e., we know that C is equal to _p_ times the capacity of a sphere of the radius, _l_; we have, therefore, C = _pl_; in the same manner we know that R is equal to _q_ times the resistance of a cube of mercury having l for its side. We l [rho] have, therefore, R = q[rho] --- = q ----- ; and consequently t = pq[rho]. l² l

Such is the value of _t_ obtained on leaving all the units undetermined. If we express [rho] as a function of the second, we have _t_ in seconds. If we take [rho] = 1, we have the absolute value [Theta] of the same interval of time as a function of this unit; we have simply [Theta] = _pq_.

If we suppose that the commutator which produces the successive charges and discharges of the condenser consists of a vibrating tuning fork, we see that the duration of a vibration is equal to the product of the two abstract numbers, _pq_.