26 
AMERICAN AGRICULTURIST. 
[January, 
toys & tmw (smuiM 
The Doctor’s Talks. 
The questions that come to me cover a wide 
range of subjects. What can be more unlike than 
the last two ?—Here is “ B. F. W.,” who wishes me 
to tell him why certain kinds of corn pop, and a 
young friend in New Jersey wants to know all about 
frost and snow. Probably one of the first crops 
raised by boys on a farm is pop-corn, and boys 
soon learn that pop-corn is different from common 
corn. It is usually a hard, flinty kind, with the 
kernels much smaller than the kinds of field corn. 
What Makes it Pop ? 
Chemists xyho have examined Indian corn, find 
that it contains all the way from 6 to 11 parts in a 
hundred (by weight) of fat. By proper means this 
fat can be separated from the grain, and it is then 
a thick pale oil. When oils are heated sufficiently 
in closed vessels, so that the air can not get to 
them, they are turned into gas, which occupies 
many times the bulk that the oil did. When pop¬ 
corn is gradually heated and made so hot that the 
oil inside of the kernels turns to gas, this gas can 
not escape through the hull of the kernels, but 
when the interior pressure gets strong enough, 
It Bursts the Grniu, 
and the explosion is so violent that it shatters it in 
the most curious manner. The starch in the grain 
becomes cooked and takes up a great deal more 
space than it did before. The other day I came 
across a kind of pop-corn, the ears of which were 
3 or 4 inches long, and no larger than my finger, 
called “Miniature Brazilian.” The grains, fig. 1, 
were the smallest I have seen. I popped some of 
it, and give you a drawing of the size of the grain 
before and after. I think, however, that some of 
the larger kinds increase much more in proportion. 
In Popping Corn, 
you need to heat it at first gradually, until the 
grains are well warmed through, and then suddenly 
increase the heat by bringing the popper nearer the 
coals, of course keeping up a lively shaking... .It 
often happens that in answering a question I must 
talk about something else first, in order to prepare 
the way. This is the case with Frost and Snow, as 
they depend upon being formed from 
The Moisture in the Air, 
without which we could have neither. When the 
books tell us that the atmosphere consists of 
oxygen and nitrogen, 
they do not state the 
whole truth, as there 
is always a variable 
amount of water in the 
air; this is invisible, 
but nevertheless pres¬ 
ent. The amount of 
moisture that the air 
can take up varies 
with the temperature. 
When the weather is 
so cold that water will 
freeze (32°), then the 
air can hold but the 
160th part of its own 
weight of the vapor of water. That is, 160 pounds 
of air can hold but one pound of water. On the 
contrary, upon a warm summer’s day, when the 
thermometer marks 86° in the shade, it can contain 
four times as much moisture, or the 40th of its 
own weight, and one pound of water can be taken 
up by forty pounds of air. When the air has all 
the vapor of water it can hold at any temperature, 
it is said to be saturated. The amount, or as the 
books have it, “the capacity of air for moisture," 
depends upon the temperature. This is an impor¬ 
tant point to remember. As just stated, by mak¬ 
ing the air 54 degrees warmer, that is, raising it from 
32° to 86°, it will take up four times as much water. 
Air that is damp at one temperature, will be very 
dry at another, although it really holds just the 
6ame amount of water. 
“How do we Know the Air is Moist?” 
some of you will ask. If you fill a pitcher with 
ice-water, taking care to have 
the outside of the pitcher per¬ 
fectly dry, you know that the 
outside will soon become 
moist, and after a while drops 
of water will trickle down, 
and if the pitcher stands on a 
paper or in a dish, a large 
space on the paper will be 
wet, or a small quantity of 
water will be caught in the 
dish. Those who do not ex¬ 
amine closely say that the 
pitcher “ sweats,” but I think 
you can understand that this 
water all comes from the air 
around the pitcher, the cold 
surface condenses the moisture. 
That the air contains more 
moisture at one time than 
another can be told in part by 
the effects upon our feelings ; 
when the air contains but little 
moisture, the skin seems dry, 
and the hair dry and harsh. It 
can be made visible by various instruments, called 
Hygrometers or nygroscopes, 
the latter name being the most correct, as these 
affairs are not really meters, that is, they do not ac ¬ 
tually measure anything, but they only show that 
the moisture in the air varies from time to time. 
Hygrometer is made up of the Greek words for 
moisture and measure. Hygroscope, from the words 
for moisture and to view, or see. I said that dry air 
would affect your hair, as that is very sensitive to 
moisture, and it is used in making the most delicate 
Hygroscopes. Figure 3 shows one of these, in 
which a long hair is stretched in such a manner 
that it can move a pointer along a scale. In a damp 
day the hair will be longer than in a dry one, and 
the movement of the pointer shows the difference. 
Hemp, flax, cotton, and other fibres are affected by 
moisture in a similar manner. You have no doubt 
noticed that a clothes line which was quite 6lack 
when dry, becomes very taut when damp, and even 
breaks when wet by the rain. You can make a rough 
Home-made Hygroscope 
with a piece of common twine. In order to show 
the changes distinctly, the string will need to be 
several feet long. You can fasten one end near the 
top of the room, and arrange the pointer low down; 
figure 4 will show how the pointer is made. You 
have no doubt seen those toys, where there is a 
little house with two doors and small figures of a 
man and woman ; on a damp day the woman moves 
in and the man comes out, and when it is dry they 
change the order of their 
going. These are often 
called “ barometers,” 
but they are only hygro¬ 
scopes, in which the 
movement is caused by 
the action of the mois¬ 
ture of the air upon a 
string of some kind. 
These are sometimes 
made in the form of a 
figure with a hood(fig.2), 
which is pulled over the 
head on damp days and 
falls back in dry ones. 
As the air is often very 
damp for some time be¬ 
fore a rain storm, these figures show that to be the 
case, and this is all that they can do in foretelling 
the weather. To come back to our question about 
Frost and Snow. 
We have already seen that the air contains 
the vapor of water, or moisture, and that cooling 
the air will cause it to let go, or deposit a part of 
it as water. When the moisture of the air is de¬ 
posited quietly and it collects on cool surfaces, we 
call it dew. If a current of warm moist air meets 
one of very cold air, the moist air is cooled, and 
can no longer hold its vapor, which condenses and 
form drops which fall as rain. If the object, the 
grass, the fence, or the bare ground becomes so 
cool that the moisture freezes as it falls, we have 
frost. When you get up on a very cold morning, 
you find the windows of your bed-room covered 
with frost, and so are the windows of other rooms 
if there is not heat enough to warm the glass faster 
than it is cooled by the air on the outside. This 
frost on the windows comes from the moisture in 
the air of the room. As dew, when the tempera¬ 
ture is very low, appears as frost, so the moisture 
that would otherwise come down as rain, freezes and 
Falls in the Form of Snow. 
I have all along assumed that you knew that ice 
was water made solid by cooling. “ Everybody 
knows that,” you will say. I admit it, but every¬ 
body does not know that when water becomes 
solid its particles arrange themselves in a regular 
form, and make crystals of definite shape, with 
always just such angles. I can not just now show 
you how that we know the solid ice is made up of 
crystals. If you watch for a fine dry snow, when 
the flakes are scarcely to be seen in the air (a few 
such snows usually occur every winter) and catch 
the little flake on a black cloth, you will find them 
of the most beautiful and regular forms. There 
are a great many things that pass from the liquid 
to the solid state—common salt, alum, blue vitriol, 
and many others, which may be dissolved in water, 
and be made to take on the solid form again and 
appear as regularly shaped crystals. It is well 
known that the more slowly these crystals are 
formed, the more regular and perfect they will be, 
If they be made to become solid quickly, they are a 
shapeless mass. Rock-candy, you know, is in 
Fig. 5.— VARIOUS FORMS OF SNOW CRYSTALS. 
handsome, regular, clear crystals ; a piece of loaf 
or lump sugar shows no distinct crystals—yet both 
are the self same sugar, and the one can be changed 
into the other. The only difference between rock- 
candy and lump sugar is, the one had time to form 
its crystals very slowly; the lump sugar became 
solid suddenly. We have reason to suppose that 
the beautiful little crystals of dry snow are formed 
slowly, while the great white flakes, which you like 
to 6ee, because they promise sleds and coasting, are 
made by the sudden cooling of the moisture, and 
many imperfect crystals 6tick together and form 
large flakes as they come down through the air. 
Our Puzzle Itox. 
COMPOUND METAMOREMS. 
(Last month we gave you simple metamorems, 
we make them a little more perplexing now, by 
letting the figure 8 stand for the word “ate,” or 
“ait” ; 1, for the letters “o-n-e” ; 10, for “ten,” 
etc.— Example. 5001=Done. 71608=State. 1900- 
10160=Intent. 
1. 10009. 4. 1000150. 7. 190010500. 
2. 20001. 5. 3000557. 8. 1001900250. 
3. 429008. 6. 40015500. 9. 2000900500150. 
SQUARE WORD. 
1. An animal that we sometimes eat. 
2. A flowering shrub. 
3. An animal that we do not eat. 
4. A vegetable. Effie, 
Fig. 3.— A HAIR 
HYGROSCOPE, 
