PLASTER OF PARIS IN AGRICULTURE
“In agriculture plaster of Paris has by no means the importance of
lime; nevertheless it produces excellent results on clover, sainfoin,
and lucerne. It is used in the spring for sprinkling the young leaves
when they are still damp with the morning dew. Still, foggy weather is
the most favorable for this work. Plaster also acts well on rape, flax,
buckwheat, and tobacco, but has no effect on cereals.
“The intelligent farmer puts plaster of Paris to still another use. In
every dunghill there is always going on a slow combustion, or
fermentation, giving forth ammonia in vaporous form; and this ammonia
escapes into the air as a total loss, whereas it ought to be retained
as far as possible in the manure, since the compounds of ammonia
constitute the source whence plants obtain nitrogen. Therefore to
prevent this waste, plaster is sprinkled over the dunghill. Sometimes,
too, it is sprinkled over each layer of manure as the pile rises. The
plaster absorbs the ammoniac vapors, gives them a little of its
sulphuric acid, and converts them into a compound, sulphate of ammonia,
which is proof against vaporization. Hence we say that plaster of Paris
fixes ammonia, that is to say prevents its being dissipated.
“To illustrate the fertilizing effect of plaster of Paris on lucerne,
the following incident is related. Franklin, one of the chief glories
of the United States of North America, aware of the great fertilizing
power of plaster, wished to extend the agricultural use of this
substance among his fellow-citizens; but they, clinging to old customs,
would not listen to him. To convince them, Franklin spread plaster over
a field of lucerne by the side of the most frequented road leading out
of Philadelphia, but spread it in such a way as to form letters and
words. The lucerne grew all over the field, but much taller, greener,
and thicker where the plaster had been applied, so that the passers-by
read in the field of lucerne these words traced in gigantic letters:
‘Plaster of Paris was applied here.’ The ingenious expedient was a
great success and plaster was very soon adopted in agriculture.”
“The doubters must have been convinced,” said Jules, “on seeing those
big green letters rising above the rest of the lucerne. Did not
Franklin do some other remarkable things? I remember the name; I have
seen it several times in books.”
“Yes,” replied his uncle, “Franklin became by his learning, one of the
most remarkable men of his time. Among other things, we owe to him the
invention of the lightning-conductor, that tall pointed iron rod
erected on the roofs of buildings to protect them from the thunderbolt.
It was he who first had the superb audacity to evoke the lightning from
the midst of the thunder-clouds, to direct it according to his wishes,
and to bring it to his feet that he might study its nature. One stormy
day in 1752 he went out into the country near Philadelphia in company
with his young son who carried a kite made out of a silk handkerchief
tied at the four corners to glass rods. A pointed piece of metal
terminated the apparatus. A long hemp cord, with a shorter cord of silk
tied to the lower end, was fastened to the kite, which was then sent up
toward a black thundercloud. At first nothing happened to confirm the
previsions of the American sage, and he was beginning to despair of
success when there came a shower of rain and with it a flash of
lightning. The wet cord proved a better conductor than when dry.
Without thinking of the danger he ran, and transported with joy at
having brought within his reach that which causes thunder, Franklin put
his finger near the cord and made little spurts of fire dart out,
lighted brandy from these sparks out of the sky, and only brought his
perilous experiment to an end when he had fully determined the origin
and nature of thunder and lightning. This was the way he studied the
mystery at close quarters, discovered its nature, and finally succeeded
in protecting buildings by means of a pointed iron rod.
“Benjamin Franklin was born in Boston, North America, in 1706. He was
the youngest [2] of seventeen children. Hence, as his father was a poor
tallow-chandler and soap-boiler, he could not acquire at home anything
beyond a knowledge of reading, writing, and arithmetic. At ten years of
age he was taken from school and set to performing small tasks about
the house. He cut candle-wicks and poured the tallow into the molds,
waited on customers in his father’s shop, and ran errands. His work
brought him in a few pence which he did not yet know how to spend
judiciously. He tells us the following little story on this subject,
which we may all profit by.
“‘One day,’ says he, ‘finding myself the possessor of a handful of
coppers, I ran out to buy some toys, when a little boy of about my own
age happened to pass that way with a whistle in his hand. Delighted
with the sound of the whistle, I proposed to my comrade to exchange all
my money for his musical instrument. To this he very willingly agreed.
Elated with my purchase, which I thought very fine, I returned home,
where I continued whistling to my great joy, but to the great
displeasure of the ears of my family. I told them of the magnificent
exchange I had just made. My brothers and sisters made fun of me,
saying that for the price I had paid I might have bought dozens of such
whistles at the toy-shop. Only then did it occur to me what fine things
I might have bought with my money, and I began to cry with vexation.
Chagrin at the exchange I had made now caused me more pain than the
whistle had before given me pleasure. This little incident made an
impression on me that has never been effaced and has been of service to
me on more than one occasion. Ever since, whenever I am tempted to buy
some useless thing, I say to myself, “Do not pay too much for your
whistle”; and so I save my money.’”