and Kennelly. "Let us see how we would come out if we tried Dyne's
proposition for, say, twenty hours, storing the energy from the
falling water for ten hours in the battery and then using this energy
during the next ten hours for re-storing the water in the upper pond.
We will say that the water-wheel furnishes eight horse-power for ten
hours--eighty horse-power hours."
I notice it is stated in this book that small dynamos are usually
unable to deliver more than 75 per cent. of the energy impressed upon
them, and storage batteries and motors deliver about 80 per cent. of
the energy impressed upon them. The accounts would, therefore, stand as
follows:
_Dynamo_ _Horse-power Hours_
_Dr._ _Cr._
To energy impressed by water-wheel 80
By energy delivered to storage battery 60
By loss in heat 20
---------
80 80
(Assuming that the battery was able to receive all the dynamo could
give.)
STORAGE BATTERY ACCOUNT
To energy impressed by dynamo 60
By energy delivered back to dynamo running
as motor 48
By loss in heat 12
---------
60 60
_Dynamo Running as Motor_ _Horse-power Hours_
_Dr._ _Cr._
To energy impressed by battery 48
By energy delivered back to water-wheel 36
By loss in heat 12
---------
48 48
(This dynamo being a particularly inefficient motor.)
We cannot give the account of a water-wheel acting as a pump, because
such a machine has not yet been perfected. It is evident however that
if a water-wheel could be devised that should be a perfect pump, the
losses in this chain of machinery are more than half; indeed, the
accounts show them to be 60 per cent. We should, therefore, be able to
return less than half the water drawn from the lake each day, and we
should rapidly move toward bankruptcy.
"Well," said Ernest, "my proposition is more successful than that,
because it sets out to be a fool proposition."
It was first suggested by the snake who undertook to swallow himself.
Suppose the account does taper down from eighty to one, so does the
snake, but he still remains "wise as a serpent." Our account would
stand as follows:
_Dynamo_ _Battery_ _Motors_
36 27 27 20 20 15
15 12 12 9 9 7
7 5 5 4 4 3
3 2 2 1 1 .8
.8 .6 .6 .48 .48 .36
.36 .27 .27 .20 .20 .15
.15 .12 .12 .09 .09 .07
.07 .05 .05 .04 .04 .03
.03 .02 .02 .01 .01 .003
It is evident that while our energy would dwindle continually we should
never quite come out of the little end of the horn, since any number
may diminish by 20 per cent. of itself indefinitely.
"Let us get at something practical," said Erg. "How are we going to
furnish electricity to the cottage when the dynamo is not running? If
we put a storage battery at the cottage, how are we going to store it
having nothing but alternating current up there; and if we attempt to
transmit current from our central station battery, how are we going to
get along with the drop in the voltage?"
"I'll tell you how to do that," said Dyne. "They want 20 amperes and
the line offers 4 ohms of resistance. That means a drop of 80 volts. We
have simply to provide a subsidiary battery of 48 cells, which we may
throw in series with our 57 cells when we supply electricity to the
cottage, and then they will have the right voltage for use out there."
"Yes," said Erg, as he rolled over, "they will have the right voltage
when they use 20 amperes, but what will happen if they simply turn on
one lamp. The drop in voltage then will be (.5 amperes × 4 ohms =) 2
volts; 105 cells at 1.8 volts a cell will send out there 189 volts
minus the drop of 2 volts, leaving 187 volts upon a lamp adapted to 110
volts, and it will immediately burn out. The same thing would happen to
any single piece of apparatus if the current was turned upon it alone.
The only thing they could do if they wanted to light a lamp, say in
the middle of the night to take a dose of medicine, would be to start
up all together, all their lamps, sewing machine, wringer, dishwasher,
fireless cooker, vacuum cleaner, etc., etc., to keep down the voltage
so that one lamp would not burn out."
"I have read," said Ernest, "that they use rectifiers, which convert
the alternating into direct current, for storing batteries. These
are much used over the country. Electric automobiles run by storage
batteries, and in the great majority of communities there is no
other electric current than the alternating. So they would be
helpless without the rectifier. We should then get another battery
of fifty-five cells for the cottage and keep it stored by using a
rectifier with our alternating current.
"But all their equipment up there," said Ernest, "is adapted to the
alternating current. Of what use would a direct current be to them?"
"Well," said Harold, "it is all the same whether you have alternating
or direct current on lamps, cooking apparatus, etc., and I have
understood that they have motors which run on both alternating and
direct currents. If so, that would fix them up all right."
The boys now turned to me for the first time to inquire whether motors
could be obtained which would run on both alternating and direct
current, and I replied that small motors for running sewing machines,
vacuum cleaners, etc., were made which would serve us, perhaps not
economically, but as they were the only solution to our problem we
could get along with them.
"Why don't they have alternating current batteries?" inquired Erg.
"Well, it is time that we learned about the nature of batteries," said
I, "if you boys are going to have two storage batteries to care for."
XIV
DOING CHORES BY ELECTRICITY
Chores were my salvation in youth, and those chores were not trifles. I
was made to feel that the whole family depended on my milking the cows,
bringing in the eggs, keeping the wood box full of wood, the water pail
full of water brought from the old well, churning the butter, feeding
and watering the animals, and performing a multitude of regular daily
and weekly tasks. As I grew older my responsibilities were allowed
to increase proportionally so that I might feel some measure of the
dignity of being a mainstay and a support of the family. Long before I
reached manhood occasional opportunities were presented for me to play
the full part of a man. These sometimes came during a temporary absence
or sickness of my father, but more often, as I learned afterward, by
his skilfully eliminating himself from the situation so that I might
try my powers.
We attempt in the present generation to furnish a substitute for the
old time chores by our daily programme in school or in summer camp,
but I often wonder whether this round of trifles can make men. Can one
grow great without having a chance to feel occasionally that the world
depends upon what he does?
[Illustration: Fig. 143]
The great advantage of Millville to us all lies in the fact that my
wife is a good organizer. She immediately saw that the introduction
of electricity into the cottage enabled her to assign chores to us
all. These chores were assigned so that the establishment ran like
clock-work. On Monday morning in a large room, called the wash room,
she arranged the soiled clothes in five piles. Pile No. 1 contained
sheets and pillow cases; No. 2, white shirts, shirtwaists, and other
starched clothes; No. 3, underclothes; No. 4, towels, etc., and No. 5,
coloured clothes. Here stood a washing machine run by electric motor
and a wringer run by the same motor (Fig. 143). By the side of it sat
a tub for rinsing water and next to that a tub for bluing water. Two
boys placed a wash boiler over a two-burner oil stove, put five pails
of water into it, and cut up one cake of laundry soap which they also
put in. When this was boiling hot, about half of it was poured into the
washing machine. The other half was to take its place later in the
washing machine. The first pile of clothes was put in and the motor
run for five minutes. This batch was then run through the wringer into
the rinsing water, and then again through the wringer into the bluing
water, and then through the wringer a third time into the clothes
basket, and hung upon the line out doors in the clear sunshine, which
did more than all else to make them sweet and clean. A basket of such
clothes from the line makes you want to plunge your face right into
it and take a good whiff. There is nothing like it except a mow full
of new hay. The piles of soiled clothes follow one another through
this series of tubs on about a fifteen to twenty minutes headway, so
that the whole family washing is done wholly by two boys inside of two
hours. Each pile after the first is given ten minutes in the washing
machine.
On Tuesday the ironing is done with electric irons (Fig. 144). On
Friday the house is cleaned by the vacuum cleaner, run by electricity
(Fig. 145).
[Illustration: Fig. 144]
[Illustration: Fig. 145]
On Saturday a lot of baking is done in a series of fireless cookers
(Fig. 146).
The sewing machine runs more than ever before. I hear "It is such fun
to sew with an electric motor." And the electric fan which Harold
installed for his mother over the sewing machine "makes that the
coolest spot in the house."
[Illustration: Fig. 146]
[Illustration: Fig. 147]
Chores do not take all of the time, nor most of the time. They
are simply the important things which must be done right on time.
Meanwhile there is plenty of time for other things and a vast lot of
experimenting goes on down at the mill. It is my chief entertainment to
stroll down there every day and look on. One day I found this project
on trial: On the floor (Fig. 148, _f_) of the room over the wash room
at the mill a large dripping pan _A_, was set on blocks of wood so that
one corner was lower than the rest. A rubber pipe, _B_, brought water
to this pan from the mill pond, an inverted faucet, _c_, regulating the
flow. The overflow from the pan fell into a funnel, _d_, the stem of
which went through a hole in the floor. A short piece of rubber pipe
connected this with the nozzle, _e_, of a gardener's sprinkling can,
which hung from the ceiling in the compartment for the shower bath.
Electric lamps attached to a board, _g_, were inverted over the pan
of water, so that the bulbs of the lamps were immersed in the water.
The electric current for these lamps was controlled by a switch, _h_,
placed by the side of the water faucet. When one wanted a shower he
could have it as cold or as hot as he chose by adjusting properly the
switch and the faucet. Moreover, it was not necessary for him to wait,
for warm water flowed immediately.
[Illustration: Fig. 148]
In discussing this the boys said that a 32-candle-power lamp used 110
watts, and that since 96 per cent. of the energy supplied to the lamps
went into heat each lamp transformed 105 watts of electrical energy
into heat. But 100 watts sufficed to raise one pint (one pound) of
water five degrees in one minute. They used seven lamps or about one
horse-power, and adjusted the flow so that the shower delivered one
quart of lake water per minute warmed for a tepid bath.
[Illustration: Fig. 149]
The next time I sauntered down to the mill the boys were working on
what they called an electric shower bath. They had fastened upon the
wall of the bath room an electric bell (Fig. 149), and placed on a
shelf near by a battery of two dry cells, _P_. The switch which closed
this primary circuit was on the wall by the side of the faucet and
electric heating switch (Fig. 148). One of the wires, _S_, for the
secondary circuit was carried up and connected to the pan _A_ (Fig.
148). The other wire was fastened to a sheet of zinc about a foot
square, which lay upon the floor of the shower bath. The idea was that
when one was taking a shower bath, if he chose to vary his sensations
he might step upon the sheet of zinc, close the switch in the primary
circuit and let the secondary current pass through his body by way of
the shower. They said that it was particularly prescribed for slow
people.
Speaking of chores, of course the most insistent chore was to keep the
storage batteries stored. This process gave rise to many questions,
through which the information contained in the next chapter was brought
out.
XV
ELECTRIC CURRENTS FROM CHEMICAL ACTION AND CHEMICAL ACTION FROM
ELECTRIC CURRENTS
Luigi Galvani (1737-1798) of Bologna, Italy, in 1786 unwittingly
produced an electric current from chemical action. Because he was
eagerly seeking other results he misinterpreted this. Several words in
the dictionary are becoming either obsolete or misnomers. For example,
galvanism is an old-fashioned word for an electric current. The
expression _galvanic electricity_ is a relic of the abandoned idea that
there are several kinds of electricity, of which Galvani discovered
one. Galvanized iron is wholly a misnomer. It is a name used for iron
which has been coated with zinc, and it suggests the idea that somehow
the zinc is coated upon the iron by means of an electric current,
whereas in fact it is done by dipping the iron into melted zinc.
Alessandro Volta (1745-1827) of Como, Italy, took up the discovery
of Galvani, interpreted it correctly, and perfected the method
of producing electricity by chemical action. What these two men
really discovered was that it is possible to produce continuous
currents of electricity. Before that electricity was known only by
the instantaneous discharge or spark. From the name of Volta is
derived the word volt, which designates the unit of electro-motive
force. The adjective _voltaic_ is synonymous with _galvanic_, as
voltaic or galvanic cell, voltaic or galvanic current. For a long
time it was thought that such an adjective was needed to designate
electric currents generated by chemical action as a peculiar kind of
electricity. We no longer think of electricity which is generated by
chemical action as different from that generated by a dynamo or from
any other source.
For about seventy-five years after the discovery of Galvani chemical
action was our only method of generating currents of electricity, and
it is largely owing to the inadequacy of this method of production that
so few uses for electricity were discovered previous to the perfection
of the dynamo about a third of a century ago. Two things have conspired
to bring about this _age of electricity_. (1) The dynamo reduced the
cost of production from five dollars to ten cents per kilowatt hour.
(2) Mankind grew extravagant, greatly increased the number of things
which it considered necessary, and at length became both able and
willing to spend more for the things which it demanded.
The so-called voltaic cell is of scarcely more than academic interest
now. The school which, as a rule, follows half a century behind
practical life, has taught and still teaches the philosophy of the
galvanic cell with great particularity. It is now being urged to
undertake the teaching of the dynamo. Meanwhile the dynamo has almost
driven out of existence all electric battery cells except the storage
cell and the so-called "dry cell," and each year the dynamo is
encroaching more and more upon the territory of the dry cell. In the
present day, when a passenger upon a street car pushes a button to stop
the car, he uses, not a voltaic cell, but a 500-volt dynamo current to
ring a small buzzer, and it costs the company not one-hundredth part
as much as it would to furnish him a battery equipment to do the same
thing. Small dynamos and magnetos are displacing dry battery cells in
the sparking equipment of motor boats and automobiles.
We lifted a dry battery cell out of its pasteboard case and found that
it was contained in a metal cup of sheet zinc. The top of this was
sealed over airtight with pitch, the purpose of which is to prevent
this "dry" cell from drying up. We dug away the hardened pitch and
found a black powder which was distinctly moist. In case the pitch
becomes cracked or a hole appears in the zinc cup, the moisture passes
out and the cell ceases to act as a generator of electric current.
The zinc cup had a lining of pasteboard on the sides and the bottom,
similar to the pasteboard which enveloped the outside, only the lining
was quite moist. A corrugated rod of carbon about an inch in diameter
occupied the middle of the cup, and the space around it was packed
full of a mixture of ammonium chloride, manganese dioxide, and other
substances like plaster, etc., which differ with different cells. A dry
cell which has been long in use is quite apt to show stains upon its
pasteboard case. These are caused by holes which appear in the zinc.
The production of electric current by the cell is dependent wholly upon
a chemical action between the zinc and the ammonium chloride which
results in the destruction of both. This chemical action cannot go on
without moisture.
The zinc cup of the particular cell which we were examining appeared
to be intact, and we proceeded to dig out the black powder. Its black
colour is due to the manganese dioxide. Ammonium chloride is white.
We lifted out the carbon rod and scraped the zinc cup clean. The
binding posts attached to both the zinc cup and the carbon rod were
left intact. Into the zinc cup we now poured a tumblerful of water
and added about a quarter of its volume of hydrochloric acid, setting
the whole into a large bowl to guard against disaster. Bubbles of gas
were formed rapidly, causing the liquid to effervesce as a tumbler of
soda water would do. We inverted an empty tumbler over the cup so as
to collect this gas. In about two minutes we lifted the tumbler, still
holding its mouth downward, and brought a lighted match to it. There
was a flash and the contents burned with a pale-blue flame. Some of
the zinc had united with some of the hydrochloric acid and set free
hydrogen gas, which is one of the constituents of the acid. This is
typical of chemical actions. Something similar takes place between the
ammonium chloride and the zinc. Three interesting things occur in this
experiment:
1. Chemical action, just described, is produced.
2. Heat is produced. This was very evident when we took the zinc cup up
in our hands. It was as hot as though boiling water had been put into
it.
3. An electro-motive force is produced. This we showed by connecting
one end of a piece of copper wire to the binding post of the zinc cup
and the other end of the wire to an electric bell. Another wire ran
from the bell to the carbon rod. When the carbon rod was lowered into
the acid the bell rang.
Within ten minutes holes began to appear in the side of the zinc cup.
The acid contents began to flow out into the bowl, and not long after
the zinc fell to pieces. After fifteen or twenty minutes the action
began to grow less. The acid was being used up as well as the zinc. If
enough acid is added the zinc will wholly disappear.
We have chosen substances which would produce striking results in this
experiment, but the same sort of thing is going on about us continually.
One summer by the seashore I fastened a brass plate upon my boat with
two screws--one of brass and one of galvanized iron. The plate was
attached below the water line so that it might be acted upon by the
salt water. Within three weeks the head of the galvanized iron screw
had entirely dissolved, while the brass screw was as good as ever. A
galvanized iron screw near by but not in contact with the brass was
still in as good order as ever. I had simply made an electric battery
cell out of the ocean by dipping into it zinc and brass in contact.
A most interesting relationship exists between the three kinds of
activity in the cell, which have been mentioned, viz.: (1) chemical
action; (2) production of heat; (3) production of electric current.
As has been already noted, chemical action produces heat. Conversely,
if we apply heat to the cell we greatly increase its chemical action.
We have also noted that chemical action produces an electric current,
but unless the current is allowed to flow through some external channel
like a closed circuit of wire the chemical action is greatly restrained
or entirely checked.
[Illustration: Fig. 150]
In a glass tumbler I put a rod of pure zinc (Fig. 150, _Zn_), and
an electric light carbon, _C_. A short wire, _a_, was arranged for
connecting the two externally. In the tumbler was put some water with
about one tenth its volume of sulphuric acid. No chemical action was
evident until the wire was touched to the zinc, closing the circuit.
Then bubbles of hydrogen gas gathered upon the surface of the carbon
rod, and clung to it very tenaciously. We lifted out the carbon rod and
rinsed off the bubbles in another tumbler of water, and then returned
the carbon to its place in the cell. The experiment was repeated many
times, and each time no bubbles of hydrogen, which is in this case the
sign of the chemical action, appeared until the circuit was closed for
the flow of the electric current. Incidentally it should be said that
the amount of hydrogen produced by the chemical action is a measure
of the amount of electric current produced. Incidentally also it
should be said that the bubbles of hydrogen clinging to the carbon rod
check and almost stop both the chemical action and the production of
electric current when the circuit is closed. If now we put in sodium
bichromate to use up the hydrogen as fast as it is produced we may have
a continuous current whenever the circuit is closed. Chemical action
does not entirely cease in this cell when the circuit is opened. But if
two cells are prepared, and one is left with its circuit closed while
the other remains with its circuit open, it will be found that the zinc
disappears and the acid is used up in the closed cell in a short time,
while these remain not greatly changed for a long time in the cell on
which the circuit is open. No cell will remain forever without chemical
action, yet a dry cell which might use up its zinc and ammonium
chloride in a few hours if the circuit is closed may be kept idle
three or four years, and still be able to furnish electricity enough to
ring a bell. Some persons feel defrauded if the author of a book fails
to give them all the new words and conventional terms which belong to
any subject. For such here is a page or so.
It is conventional to speak of the electric current as flowing from the
carbon through the wire to the zinc, although every one has suspicions
that it may flow in the other direction or even that it may not flow
at all. It is conventional to designate any part of the circuit from
which the current comes as positive (+) to any other part toward
which it flows, this latter being considered negative to the former
and designated (-). The current is conceived of as making a complete
circuit, from carbon to zinc through the wire and from zinc to carbon
through the liquid. Hence, the binding post of the carbon rod is called
the + pole and that of the zinc is called the-pole, while the zinc rod
or plate beneath the surface of the fluid is called the + plate and
the carbon is called the-plate. The liquid is termed the electrolyte.
The sodium bichromate, introduced to cause the hydrogen to unite with
oxygen, is called an oxidizing agent or even a _depolarizing_ agent,
and hydrogen collecting upon the negative plate is said to polarize
the cell.
Hydrogen may be made to collect upon the carbon or negative plate until
the electric current reverses its direction. The hydrogen is said to be
more - than the zinc. If we connect the zinc and carbon rods with the
wires bringing an electric current from the dynamo we may make either
one positive as we choose, according to which is connected with the
positive wire. Hydrogen bubbles will collect upon whichever plate we
make the negative one.