Cold is a
negative condition, and depends on the absence, or privation, of heat.
Intense artificial cold may be produced by the rapid absorption of heat
during the conversion of solids into liquids. Dr. Black long since discovered
the principle, that when bodies pass from a denser to a rarer state, heat is
absorbed and becomes latent in the body so transformed, and consequently cold
is produced. And also that when bodies pass from a rarer to a denser state,
their latent heat is evolved, and becomes sensible.
It is
known to almost everyone, that dissolving common salt in water, particularly
if the salt is fine, will render the water so cold, even in summer, as to be
painful to the hand. The salt, as it passes from the solid to the liquid
state, absorbs caloric from the water, and thus the heat that was before sensible, becomes latent, and cold is produced.
On the
contrary, when a piece of lead, or iron, is beaten smartly with a hammer, it
becomes hot, because the metal, in consequence of the hammering, has its
capacity for caloric reduced, and thus the heat which was before latent, now
becomes sensible. For the same reason, when air is compressed forcibly in a
tube, or as it is sometimes called, in a fire-pump, the heat, which
was before latent, becomes sensible, because the condensation lessens its
capacity for caloric.
The
principle on which all freezing mixtures act is therefore the change of state
which one or more of the articles employed undergo, during the process, and
this change consists in an enlarged capacity for caloric. The degree of cold
will then depend on the quantity of caloric which passes from a free to a
latent state, and this again will depend on the quantity of substance
liquefied, and the rapidity of the liquefaction.
The
substances most commonly employed for this purpose are those originally used
by Fahrenheit, to produce the zero of his thermometric scale; viz. common
salt and snow, or pounded ice. For this purpose the salt should be fine, and
the ice, which must always be used in summer, is to be reduced to small
particles in a cold mortar.
The
vessel to contain the substance to be frozen may be made of tin, and of the
shape represented by the figure below. It is simply a tall vessel, holding
a few pints, with a close cover, and a rim round the top, for the
convenience of handling it. For common purposes, this may be set into any
convenient wooden vessel (having first introduced the substance to be
frozen) and then surrounded by the freezing mixture. The only care to be
taken in this part of the process is to see that the freezing mixture in
the outside vessel reaches as high as the contents of the internal one.
With two or three pounds of fine common salt, and double this weight of
pounded ice, three or four pints of iced cream may be made in this way,
during the warmest days of summer. The process requires two or three hours,
and while it is going on, the vessel should be set in a cellar, or covered
with a flannel cloth, as a bad conductor of the external heat.
From J.L. Comstack,
Elements of Chemistry.
1.
After reading the
above passage, the reader could correctly infer that dissolving sugar in
hot tea will
A.
the
temperature of the hot tea.
B.
the temperature of the tea to become even warmer just as beating a piece
of lead with a hammer will raise its temperature.
C.
the temperature of hot tea so that if it were placed about cream in a tin
container, the cream would freeze within two to three hours.
D.
the temperature of the hot tea to such a low temperature as to be
painful to the hand.
2.
The drop in
temperature which occurs when sugar is added to coffee is the result of
I. sugar passing from a
solid to a liquid state.
II. sugar absorbing caloric from the water.
III. heat becoming latent when it was
sensible.
A.
B.
C.
D.
3.
Which is the best example of Dr. Black's discovery as
outlined in the article?
A.
B.
C.
D.
4.
The
narrator seems to base this article on
A.
sociological study.
B.
methods.
C.
procedures.
D.
research.
5.
The
word "mortar" as used in this article can be best
interpreted to mean
A.
which can fix or hold together, as
mortar holds bricks.
B.
weapon, a piece of artillery, or a small
cannon.
C.
container used for grinding or mixing.
D.
mixture; for example, the
particles should be made smaller by combining with
other ingredients in a mixture.
6.
The
writer does not make use of
A.
.
B.
.
C.
.
D.
.
7.
In
pumping up a basketball, one can infer from this
article that the metal needle going into the ball
A.
become warm.
B.
not be affected by the
process since metal is strong.
C.
become cooler.
D.
quickly reach a freezing
temperature.
8.
The writer can be best described as
A.
with literary
form and stylistic devices.
B.
in his writing.
C.
.
D.
facts which are new to most scientists in
the late twentieth century.
9.
A positive condition
depending on the absence of cold is
A.
B.
artificial cold.
C.
.
D.
rarer
state, according to Black.
10.
Black found that
when bodies pass from a rarer to a
denser state, their latent heat is
evolved, and becomes sensible.
"Sensible" can be interpreted
to be
A.
, making sense.
B.
.
C.
.
D.
.
ANSWER KEY
1.
After reading the
above passage, the reader could
correctly infer that dissolving sugar
in hot tea will
A.
the temperature of the hot
tea.
B.
the temperature of the tea to
become even warmer just as beating a
piece of lead with a hammer will raise
its temperature.
C.
the temperature of hot tea so
that if it were placed about cream in a
tin container, the cream would freeze
within two to three hours.
D.
the temperature of the hot
tea to such a low temperature as to be
painful to the hand.
Explanation:
(A) is the best answer
since, as stated in the third sentence
of the passage, changing the solid to
liquid will lower the temperature of
the hot tea. Because changing the sugar
to liquid will not raise, but rather
lower, the temperature of the tea, (B)
should not be selected. The temperature
of the hot tea will not be lowered to such
an extent that it will freeze cream (C)
or cause the hand to be painful from
the cold (D). Both (C) and (D) are
unacceptable.
Section:
ACT Reading Test II
Subsection:
Social Studies/Science
2.
The drop in
temperature which occurs when sugar is
added to coffee is the result of
I. sugar passing from a solid to
a liquid state.
II. sugar
absorbing caloric from the water.
III. heat
becoming latent when it was sensible.
A.
B.
C.
D.
Explanation:
The best answer is
(C) since it includes three correct
statements. The sugar does pass from a
solid to a liquid state, the sugar does
absorb caloric from the water, and the
heat does become latent when it is
sensible. Since I,
II, and III are all causes of the drop
of temperature when sugar is added to
coffee, all three must be included when
choosing an answer. (A) states that sugar
passes from a solid to a liquid state
(I), but no other information is given.
(B) includes
two true statements (I and II), but it
does not include all the information
since there is no mention of heat
becoming latent when it was sensible
(III). (D) is
not a proper answer since it excludes
statement II—that sugar absorbs caloric
from the water. While (A), (B), and (D)
each contain one or more of these
statements, none contains all three;
subsequently, each of these choices is
incorrect.
Section:
ACT Reading Test II
Subsection:
Social Studies/Science
3.
Which is the best example of Dr.
Black's discovery as outlined in
the article?
A.
B.
C.
D.
Explanation:
The best answer is
(D). Answer (D) states that one should
take into consideration that dissolving
the salt in the water will lower the
temperature of the water and that one
should start with water that is warmer
than is desired. One should not start
with water that is cooler than one
desires; (A) is not the best answer. The
order of adding the salt and then the
water or the water and then the salt
will make little difference; the
temperature will be lowered in both
instances; (B) is not the best answer.
The salt will lower the temperature of
the water; (C) suggests that this will
not happen if the salt is fine, so (C)
is not an acceptable choice.
Section:
ACT Reading Test II
Subsection:
Social Studies/Science
4.
The narrator seems
to base this article on
A.
sociological study.
B.
methods.
C.
procedures.
D.
research.
Explanation:
The writing seems
scientific since it refers to
principles, causes and effects, and
measures of heat and cold; (C) is the
best answer. The writing is not
sociological since there is little
description of people and their
relationships; consequently, (A) should
not be chosen. Because the narrator
reports scientific facts and there is
no trial-and-error reporting, (B) is
not the best answer. Since the information
is not reported as historical research
with references, footnotes, or dates of
previous discoveries, (D) should not be
chosen.
Section:
ACT Reading Test II
Subsection:
Social Studies/Science
5.
The word
"mortar" as used in this
article can be best interpreted to mean
A.
which can fix or hold
together, as mortar holds bricks.
B.
weapon, a
piece of artillery, or a small cannon.
C.
container
used for grinding or mixing.
D.
mixture;
for example, the particles should be
made smaller by combining with other
ingredients in a mixture.
Explanation:
The best choice is
(C); paragraph five shows that in this
case a mortar is a container used for
pounding, pulverizing, and/or mixing.
As employed in the last sentence of the
fifth paragraph, the use of the mortar
is not to fix or hold together; (A)
should not be chosen. A mortar can be a
weapon (B), but that would not be used
to reduce ice to small particles;
therefore, (B) is not an acceptable
choice. The word does not fit into the
sentence; the mixture is to be that of
salt and ice which must be contained
somewhere. Choice (D) would not be
practical.
Section:
ACT Reading Test II
Subsection:
Social Studies/Science
6.
The writer does
not make use of
A.
.
B.
.
C.
.
D.
.
Explanation:
The best choice is
(B). The only device that the writer
does not record is that of interviews.
The other items—descriptions (A),
mathematics (C), and experiments (D)—are used; the
question, however, asks what items are
NOT used.
Section:
ACT Reading Test II
Subsection:
Social Studies/Science
7.
In pumping up a
basketball, one can infer from this
article that the metal needle going
into the ball
A.
become warm.
B.
not be affected by the
process since metal is strong.
C.
become cooler.
D.
quickly reach a freezing
temperature.
Explanation:
One can infer that
the metal needle will become warm when
the basketball is being pumped up by
the air pump. The reason is that the
article states, "…air is compressed
forcibly in a tube…the heat, which was
before latent, becomes sensible…"; (A) is the
correct answer. Choice (B) states that
the needle will not be affected; (B)
should not be chosen since the
quotation from the passage states that
there will be an effect, rather than no
effect. (C) is also incorrect because
it states that the needle will become
cooler, not warmer. (D) is an incorrect
choice; it incorrectly states that the
needle will become freezing cold.
Section:
ACT Reading Test II
Subsection:
Social Studies/Science
8.
The writer can be
best described as
A.
with literary form and
stylistic devices.
B.
in his writing.
C.
.
D.
facts which are new to most
scientists in the late twentieth
century.
Explanation:
The writer is
objective in his writing and offers no
opinions of his own; (C) is the best
answer. The writer's main concern is
not literary form or stylistic
devices; (A) is not acceptable.
The writer is objective and does not
offer his own opinions; since he is not
subjective, (B) is not the best answer.
Since the facts presented in the
article are not new, (D) is not the
best answer.
Section:
ACT Reading Test II
Subsection:
Social Studies/Science
9.
A positive
condition depending on the absence of
cold is
A.
B.
artificial cold.
C.
.
D.
rarer
state, according to Black.
Explanation:
Since heat is a
positive condition depending on the
absence of cold, (C) is the best
answer. Fahrenheit is a measure of
temperature, not a condition;
therefore, (A) is an incorrect choice.
Heat is the opposite of intense
artificial cold; (B) is not acceptable.
Black states that it is "…when
bodies pass from a rarer to a denser
state that their latent heat is
evolved…";
(D) is incorrect because it says that,
"A positive condition depending on
the absence of cold is a rarer state
according to Black."
Section:
ACT Reading Test II
Subsection:
Social Studies/Science
10.
Black found that
when bodies pass from a rarer to a
denser state, their latent heat is
evolved, and becomes sensible.
"Sensible" can be interpreted
to be
A.
, making sense.
B.
.
C.
.
D.
.
Explanation:
In this case, the
word "sensible" means
perceptible; (D) is the best answer.
"Sensible" can mean
knowledgeable (A), but the definition
does not make sense in this case. The
meaning of "sensible" can be
logical (B), but that particular meaning
does not fit the sentence or passage
here. "Evolving" (C) is not
an acceptable answer because it does
not seem to fit the context; (C) should
not be chosen.
