A GUIDE TO THE SCIENTIFIC KNOWLEDGE OF THINGS FAMILIAR;
BY
THE REV. DR. BREWER,
TRINITY HALL, CAMBRIDGE,
HEAD MASTER OF KING'S COLLEGE SCHOOL,
NORWICH,
IN UNION WITH KING'S COLLEGE, LONDON.
LONDON:
JARROLD AND SONS, 47, ST. PAUL'S CHURCHYARD,
ALSO HAMILTON AND CO., SIMPKIN AND CO.,
AND WHITTAKER AND CO.
PREFACE.
Of all science, none is more generally interesting than that which
explains the common phenomena of life. We see that salt and snow are
both white, a rose red, leaves green, and the violet a deep purple; but
how few persons ever ask the reason why! We know that a flute produces a
musical sound, and a cracked bell a discordant one--that fire is hot,
ice cold, and a candle luminous--that water boils when subjected to
heat, and freezes from cold; but when a child looks up into our face and
asks us "why,"--how many times is it silenced with a frown, or called
"very foolish for asking such silly questions!" The object of the
present book is to explain about 2000 of these "silly questions" (which
are often more easily asked than answered) in language so simple that a
child may understand it, yet not so childish as to offend the
scientific; and in order that the answers may be strictly correct, not
only the most approved modern authors have been consulted, but the
manuscript has been submitted sheet by sheet to the revision of two
gentlemen of acknowledged reputation for scientific attainments. To the
REV. A. BATH POWER, M. A. especially, great obligation is due, for a
careful revision of the whole manuscript, for many excellent hints, and
useful additions. In conclusion, so much diligence has been bestowed
upon this little work for nearly ten years, so much useful information
has been supplied by scientific friends, and so minute a revision has
been made of every answer, that it is no presumption to express a hope
that this "Guide to the Scientific Knowledge of Things Familiar" will
become generally useful and acceptable, not only to the young, but to
those advanced to maturer life.
In this work some questions occur more than once, because they serve to
illustrate different principles; and whenever cognate questions occur,
the answers have been rendered as similar as possible, in order to
assist the memory of the learner.
SUBJECTS OF THE CHAPTERS.
PART I.--HEAT.
I.--The SUN a source of heat
II.--ELECTRICITY a source of heat
Thunder and lightning
III.--CHEMICAL ACTION a source of heat
III.--Combustion
IV.--Smoke and smoky chimneys
V.--Lamps and candles
VI.--Animal heat
VII.--MECHANICAL ACTION a source of heat
VII.--Percussion
VIII.--Friction
VIII.--Compression
IX.--EFFECTS OF HEAT
X.--Expansion
XI.--Liquefaction
XI.--Vaporization (clouds)
XII.--Evaporation
XIII.--COMMUNICATION OF HEAT
XIII.--Conduction
XIV.--Absorption
XV.--Reflection
XVI.--Radiation (dew)
XVII.--Convection (boiling)
PART II.--AIR.
XVIII.--AIR
Rust
Tarnish
XIX.--CARBONIC ACID GAS
Froth
Effervescence
Fermentation, &c.
XX.--CARBURETTED HYDROGEN GAS
Fire damp
Safety lamp
XXI.--PHOSPHURETTED HYDROGEN GAS
Ignis fatuus
Ghosts
XXII.--WIND
XXIII.--BAROMETER
Ten special Rules
XXIV.--SNOW. HAIL. RAIN
XXV.--WATER
XXVI.--ICE
Frost
Freezing mixtures
XXVII.--LIGHT
Reflection
Telescopes
Refraction
Spectacles
Rainbows
Colour
XXVIII.--SOUND
Ear trumpets
Echoes
XXIX.--MISCELLANEOUS
Attraction
Anti-putrescents
Sleep
Dreams
Glossary
Index
PART I.
HEAT.
INTRODUCTION.
Q. _What is heat?_
A. The sensation of warmth.
Q. _How is this sensation produced?_
A. When we touch a substance of higher temperature than ourselves, the
warmer substance keeps parting with its heat, till both are of equal
temperature.
Q. _What is that "stream of heat" called, which flows thus, from one
body, to another?_
A. CALO'RIC. _Caloric_, therefore, is the _matter of heat_, which passes
from body to body; but HEAT is the _sensation, of warmth_, produced by
the influx of Calo'ric.
Q. _What are the four principal_ SOURCES _of heat_?
A. 1.--The Sun. 2.--Electricity. 3.--Chemical Action: and 4.--Mechanical
Action.
Q. _What are the principal_ EFFECTS _of heat_?
A. Expansion, Liquefaction, Vaporization, and Ignition.
CHAPTER I.
Q. _What is the_ PRINCIPAL _source of Heat_?
A. The SUN.
Q. _Why do_ BURNING GLASSES _set fire to substances submitted to their
power_?
A. The rays of the sun, collected by the Burning Glass, are all _bent to
one point_, called the "focus;" thus the heat and light, (which should
be diffused over the _whole_ glass,) being gathered together into one
point, are very greatly increased.
Q. _Why is there a_ DARK RIM _round this focus_?
A. Because the rays of light, which should have fallen there, are _bent
into the focus_, and the space around, (being deprived of these rays) is
accordingly darkened.
Q. _Are_ ALL _the rays bent into one point_?
A. No, not quite all: and, therefore, the rim round the focus is only
_slightly_ shadowed.