Index

PREFACE TO THE REVISED AND ENLARGED EDITION 1871 INTRODUCTION DIVISIONS OF THE SUBJECT OF MATTER AND ITS PROPERTIES OF GRAVITY MECHANICS, on THE LAWS OF MOTION THE MECHANICAL POWERS REGULATORS OF MOTION HYDROSTATICS HYDRAULICS PNEUMATICS ACOUSTICS

PYRONOMICS THE STEAM-ENGINE OPTICS ELECTRICITY GALVANISM, OR VOLTAIC ELECTRICITY MAGNETISM ELECTRO MAGNETISM THE ELECTROMAGNETIC TELEGRAPH THE ELECTROTYPE PROCESS MAGNETO-ELECTRICITY THERMO-ELECTRICITY ASTRONOMY

OF MATTER AND ITS PEOPERTIES

What is Matter?

22. MATTER. Matter is the general name of everything that occupies space.
23. Matter exists in three different states or forms namely, in the solid, liquid, and gaseous forms.
24. Matter exists in a solid form when the particles of which it is composed cohere together. The different degrees of cohesion which different bodies possess causes them to assume different degrees of hardness.
25. Matter exists in a liquid state when the component parts do not cohere with sufficient force to prevent their separation by the mere influence of their weight. The surface of a fluid at rest always conforms itself to the shape of the portion of the earth’s surface over which it stands.
26. Matter exists in a gaseous or aeriform state when the particles of which it is composed have a repulsion towards each other which causes them to separate with a power of expansion to which there is no known limit. Of this, smoke presents a familiar instance. As it ascends it expands, the particles repelling each other until they become wholly invisible.

NOTE. The word aeriform means, in the form of air.

27. The vesicular form of matter is the form in which we see it in clouds. It consists of very minute vesicles, resembling bubbles, arid it is the state into which many vapors pass before they assume a fluid condition.
28. Some substances are capable, under certain conditions, of assuming all these different forms. Water, for instance, is solid in the form of ice, fluid as water, in the gaseous state when converted into steam, and vesicular in the form of clouds.
29. All matter, whether in the solid, liquid, gaseous, or vesicular form, is either simple or compound in its nature. But this consideration of matter pertains more properly to the science of chemistry. It is proper, however, here to explain what is meant by a simple or homogeneous and a compound or heterogeneous substance.
30. All matter is composed of very minute particles or atoms united together by different degrees of cohesion. When all the atoms are of the same kind, the body is a simple or homogeneous substance. Thus, for instance, pure iron, pure gold, &c., consists of very minute particles or atoms, all of which are pure iron or pure gold. But water, and many other substances, are compound substances, composed of atoms of two or more different substances, Combined by chemical affinity.

page 20

NOTE. The ancient philosophers supposed that all material substances were composed of Fire, Air, Earth and Water, and these four substances were called the four elements, because they were supposed to be the simple substances of which all things are composed. But modern science has shown that not one of these is a simple substance. Water, for instance, is composed of two invisible gases, called Hydrogen and Oxygen, united in the proportion of one part, in weight, of hydrogen to eight of oxygen; or, by measure, one part of oxygen to two of hydrogen. In like manner air, or, rather, what the ancients understood by air, is composed of oxygen mixed with another invisible gas, called nitrogen or azote, in the proportion of seventy-two parts of the latter to twenty-eight of the former.

The enumeration of the elementary substances, which, either by themselves or in union with one another, make up the material world, properly belongs to the science of Chemistry. As this work may fall into the hands of some who will not find the information elsewhere, a list of the simple substances or elements is presented, so far as modern science has investigated them. They are sixty-three in number, forty-nine of which are metallic, and fourteen are non-metallic.

The forty-nine metals are

Gold, Silver, Iron, Copper, Tin, Mercury, Lead, Zinc, Nickel,

Cobalt, Bismuth, Platinum, Antimony, Arsenic, Manganese, Cadmium, Uranium, Palladium,

Rhodium, Iridium, Osmium, Titanium, Cesium, Tungsten, Molybdenum. Vanadium, Chromium,

The non-metallic elements are

Oxygen, Sulphur, Hydrogen, Phosphorus, Nitrogen, Carbon, Chlorine, Potassium, Sodium, Lithium, Barium, Strontium,

Calcium, Magnesium, Aluminum, Glucinum, Yttrium, Zirconium, Thorium, Cerium, Lanthanium, Bromine, Iodine, Selenium,

Fluorine, Didynium, Tantalum^ Erbium, Thallium, Ruthenium, Rubidium, Niobium, Indium. Boron, Silicon, Tellurium.

Of the elementary substances now enumerated, about fourteen constitute the great mass of our earth and its atmosphere. The remainder occur only in comparatively small quantities, while nearly a third of the whole number is so rare that their uses in the great economy of nature are not understood, nor have they as yet admitted of any useful application.

The science of Geology reveals to us the fact that granite appears to be the foundation of the crust of the earth, and in the granite, either in its original formation or in veins or seams which, have been thrown up by subterranean forces into the granite, all of the elementary substances which have been enumerated are to be found. A chart is presented below in which the materials composing the strata of the crust of the earth are enumerated, together with a tabular view of the composition of these materials. It is not contended that this chart is perfectly accurate in all its details, but as it affords an interesting and extensive subject of investigation, and as it is not to be found elsewhere in print, it is thought that it will be well worth the space which it occupies, although a rigid classification would exclude it from this work.

page 21

Dr. Boyntoris Chart of Materials that enter into the Composition of Granite.

	Silica	Alumina	Potash	Soda	Lime	Magnesia	Ox.Iron	Ox.Manganese	Water	Carb.Acid
Quartz	100
Feldspat	65	19	14		1		1
Albite	70	20		10
Mica	46	26	10		1	5	8 Prot Ox.	1	2		2 Fluor Acid
Hornblende	48	12			14	19	7
Augite	54	1			24	17	4
Diallage	47	4			13	25	8 M.		3
Chlorite	27	18	2			15	31 Prot		7
Talc	57	1			4	27	8		3
Hypersthene	56	2			2	14	25		1
Actinolite	56	2			12	13	17 M.
Steatite	62	1			1	28	2		6
Serpentine	42				5	33	7		13
Schorl	36	36	1	2		5	14 Prot	2			4 B. Acid
Garnet	40	20			1		36 Prot	3 Prot
M. Garnet	36	18					15	31
Clay	75	10			5	2	3 Prot
Green Sand	48	7	8				26		11
Carbonate of Lime					56						44 Carb. Acid
Carbonate of Magnesia						48			2		50 Carb. Acid

 

What are the essential properties Matter?

31. There are seven essential * properties belonging to matter, namely,
    1. Impenetrability; 2. Extension; 3. Figure; 4. Divisibility; 5. Indestructibility; 6. Inertia; 7. Attraction.

What is Impenetrability?

32. IMPENETRABILITY. Impenetrability is the power of occupying a certain portion of space, so that where one body is another cannot be without displacing it.

* An essential property of a body is that which is necessary to the absolute existence of the body. All matter in common possesses these essential properties, and no particle of matter can exist without any any one of them. Different bodies possess other different properties which are not essential to their existence, such as color, weight, brittleness, hardness &c. These are called accidental properties, as they depend on circumstances not essential to the very existence of a body.

page 22

33. This property, Impenetrability, belongs to all bodies and forms of matter, whether solid, fluid, gaseous, or vesicular.

The impenetrability of common air may be shown by immersing an inverted tumbler in a vessel of water. The air prevents the water from rising into the tumbler. An empty bottle, also, forcibly held horizontally under the water, will exhibit the same property, for the bottle, apparently empty, is tilled with air, which escapes in bubbles from the bottle as the water enters it. But, if the bottle be inverted, the water cannot enter the bottle, on account of the impenetrability of the air within.*

* This circumstance explains the reason why water, or any other liquid, poured into a tunnel closely inserted in the mouth of a decanter, will run over the sides of the decanter. The air filling the decanter, and having no means of escape, prevents the fluid from entering the decanter, but, if the tunnel be lifted from the decanter but a little, so as to afford the air an opportunity to escape, the water will then flow into the decanter in an uninterrupted stream.

When a nail is driven into wood or any other substances, it forces the particles asunder and makes its way between them.

An experiment was made at Florence, many years ago, to show the impenetrability of water. A hollow globe of gold was filled with water and subjected to great pressure. The water, having no other means of escape, was seen to exude from the pores of the gold.

The reason why fluids appear less impenetrable than solids is that the particles which compose the fluids move easily among themselves, on account of their slight degree of cohesion, and when any pressure is exerted upon a fluid the particles move readily into the unoccupied space to which they have access. But, if the fluid be surrounded on all sides, and have no means of escape, it will be found to possess the property of impenetrability in no less a degree than solid bodies.

A well-known fact seems, at first view, to be at variance with this statement. When a vessel is filled to the brim with water or other fluid, a considerable portion of salt may be dropped into the fluid without causing the vessel to overflow. And, when salt has been added until the water can hold no more in solution, a considerable quantity of sugar can be added in a similar manner.

The explanation of this familiar fact is as follows the particles of the sugar are smaller than the particles of the salt and the particles of the salt are smaller than the particles which compose the water. Now, supposing all of these particles to be globular, they will arrange themselves as is represented in Fig. 1, in which the particles of the water are indicated by the largest circles, those of the salt by the next in size, and those of the sugar by the smallest.

Familiar Experiment. – Fill a bowl or tumbler with peas, then pour on the peas mustard-seed or fine grain, shaking the vessel to cause it to fill the vacant spaces between the peas. In like manner add, successively, fine sand, water, salt and sugar. This will afford an illustration of the apparent paradox of two bodies occupying the same space, and show that it is only apparent.

page 23

What is Extension?

34: EXTENSION. Extension is but another name for bulk or size, and it is expressed by the terms length, breadth or width, height, depth and thickness.

NOTE. – – Length is the extent from end to end. Breadth or width is the extent from side to side. Height, depth or thickness, is the extent from the top to the bottom. The measure of a body from the bottom to the top is called height, from the top to the bottom, is called depth. Thus we speak of the depth of a well, the height of a house, &c.

What is Figure?

35. Figure is the form or shape of a body.
36. Figure and Extension are separate properties, although both may be represented by the same terms, length, breadth, &c. But they differ as the words shape and size differ. Two bodies may be of the same figure or shape, but of vastly different size. A grape and an orange resemble each other in shape, but differ widely in size.

The limits of extension constitute figure, but figure has no other connexion with extension.

What is Divisibility?

37. DIVISIBILITY. Divisibility is susceptibility of being divided.
38. To the divisibility of matter there is no known limit, nor can we conceive of anything so small that it is not made up of two halves or four quarters. It is indeed true that our senses are quite limited in their operation, and that we cannot perceive or take cognizance, by means of our senses, of many objects of the existence of which we are convinced without their immediate and direct testimony.
39. Sir Isaac Newton has shown that the thickest part of a soap bubble does not exceed the two-millionth part of an inch.
40. The microscopic observations of Ehrenberg have proved that there are many species of little creatures, called Infusoria, so small that millions of them collected into a single mass would not exceed the bulk of a grain of sand, and thousands of them might swim side by side through the eye of a small needle.
41. In the slate formations in Bohemia these little creatures are found in a fossil state, so small that it would require a hundred and eighty-seven millions of them to weigh a single grain.
42. A single thread of the spider’s web has been found to be composed of six thousand filaments.
43. A single grain of gold may be hammered by a gold-beater until it will cover fifty square inches, each square inch may be divided into two hundred strips, and each strip into two hundred parts. One of these parts is only OIK two-millionth part of a grain of gold, and yet it may be seen with the naked eye.

page 24

44. The particles which escape from odoriferous objects also afford instances of extreme divisibility.

What is Indestructibility?

45. INDESTRUCTIBILITY. By the Indestructibility of matter is meant that it cannot be destroyed.
46. A body may be indefinitely divided or altered in its form, color, and other unessential properties, but it can never be destroyed by man. It must continue to exist in some form, with all its essential properties, through all its changes of external appearance. HE alone „who can create can destroy.“
47. When water disappears, either by boiling over a fire or by evaporation under the heat of the sun, it is not destroyed, but merely changed from a liquid to a fluid form, and becomes steam or vapor. Some of its unessential properties are altered, but it’s essential properties remain the same, under all the changes which it undergoes. In the form of water it has no elasticity* and but a limited degree of compressability.* But when „it dries up“ (as it is called) it rises in the form of steam or vapor, and expands to such a degree as to become invisible. It then assumes other properties, not possessed before (such as elasticity and expansibility), it ascends In the air and forms clouds, these clouds, affected by the temperature of the air and other agents, again fall to the earth in the form of rain, hail, snow or sleet, and form springs, fountains, rivers, &c

The water on or in the earth, therefore, is constantly changing its shape or situation, but no particle of it is ever actually destroyed.

48. Substances used as fuel, whether in the form of wood, coal, or other materials, in like manner undergo many changes by the process of combustion. Parts of them rise in the form of smoke, part ascends in vapor, while the remainder is reduced to the form of ashes, but no part is absolutely destroyed. Combustion merely disunites the simple substances of which the burning materials are composed, forming them into new combinations, but every part still continues in existence, and retains all the essential** properties of bodies.

What is Inertia?

49. INERTIA. Inertia*** is the resistance of matter to a change of state, whether of motion or of rest.

* Late writers assert that water has a slight degree both of elasticity and expansibility.

** The reader will be careful to carry in his mind what is meant by the term an essential property. It is explained in the note to No. 31, page 21

*** The literal meaning of inertia is inactivity, and implies inability to change a state of rest or of motion. A clear and distinct understanding of this property of all matter is essential in all the departments of material philosophy. All matter, mechanically considered, must be in a state either

page 25

of motion or rest, and, in whatever state it may be, it must remain in that state until a change is effected by some efficient cause, independent of the body itself. A body placed upon another body in motion partakes of the motion of the body on which it is placid. But, if that body be suddenly stopped, the superincumbent body will not stop at the same time, unless it be securely fastened. Thus, if a horse moving at a rapid rate be suddenly stopped, the rider will be thrown forward, on account of this inertia of his body, unless by extra exertion he secures himself on the saddle by bracing his feet on the stirrups. On the contrary, if the horse, from a state of rest, start suddenly forward, the rider will be thrown backwards. For the same reason, when a person jumps from a vehicle in motion to the ground, his body, partaking of the motion of the vehicle, cannot be suddenly brought to a state of rest by his feet resting on the ground, but will be thrown forward in the direction of the motion which it has acquired from the vehicle. This is the reason that so many accidents happen from leaping from a vehicle in motion.

50. A body at rest cannot put itself in motion, nor can a body in motion stop itself. This incapacity to change its state from rest to motion, or from motion to a state of rest, is what is implied by the term inertia.
51. It follows, therefore, from what has just been stated, that when a body is in motion its inertia will cause it to continue to move until its motion is destroyed by some other force.
52. There are two forces constantly exerted around us which tend to destroy motion, namely, gravity and the resistance of the air. All motion caused by animal or mechanical power is affected by these two forces. Gravity (which will presently be explained) causes all bodies, whether in motion or at rest, to tend towards the centre of the earth, and the air presents a resistance to all bodies moving in it. Could these and all other direct obstacles to motion be set aside, a body when once put in motion would always remain in motion, and a body at rest, unaffected by any external force, would always remain at rest.*

* In the absence of all positive proof from the things around us of the statement just made, we may find from the truths which astronomy teaches that inertia is one of the necessary properties of all matter. The heavenly bodies, launched by the hand of their Creator into the fields of Infinite space, with no opposing force but gravity alone, have performed their stated revolutions in perfect consistency with the character which this property gives them; and all the calculations which have been made with respect to them, verified as they have repeatedly been by observation, have been predicated on their possession of this necessary property of all matter.

53. Experiment to illustrate Inertia.

Fig. 2 represents the simple apparatus of Mr. Wightman for illustrating the inertia of a body. A card is placed on the top of a stand, and a ball is balanced on the card. A quick motion

page 26

is then given to the card by means of a spring, and the card flies off, leaving the ball on the top of the stand.*

* The ball remains on the pillar in this case not solely from its inertia, but because sufficient motion is not communicated to the ball by the friction of the card-to counteract the effect of gravity on the ball. If the ball, therefore, be not accurately balanced on the card, the experiment will not be successful, because the card cannot move without communicating at least a portion of its motion to the ball.

54. Nature seems to have engrafted some knowledge of mechanical laws on the instinct of animals. When an animal, and especially a large animal, is in rapid motion, he cannot (on account of the inertia of his body) suddenly stop his motion, or change its direction, and the larger the animal the more difficult does a sudden stoppage become. The hare pursued by the hound often escapes, when the dog is nearly upon him, by a sudden turn, or changing the direction of its flight, thus gaining time upon his pursuer, whose inertia is not so readily overcome, and who is thus impelled forward beyond the spot where the hare turned.
55. Children at play are in the same manner enabled „to dodge“ their elder playmates, and the activity of a boy will often enable him to escape the pursuit of a man.
56. It is the effect of inertia to render us sensible to mention. A person in motion would be quite unconscious of that state, were it not for the obstacles which have a tendency to impede his progress.

In a boat on smooth water, motion is perceptible only by the apparent change in the position of surrounding objects, but, if the course of the boat be interrupted by running aground, or striking against a rock, the person in the boat would feel the shock caused by the sudden change from a state of motion to a state of rest, and, unless secured to his seat in the boat, he would be precipitated forward

What is Attraction?

57. ATTRACTION. Attraction is the tendency which different bodies or portions of matter have to approach or to adhere to each other.

What is the law of Attraction?

58. Every portion of matter is attracted by every other portion of matter, and this attraction is the stronger in proportion to the quantity and the distance. The larger the quantity and the less the distance, the stronger is the attraction. **

** [N.B. This subject will be more fully treated under the head of Gravity. See page 33.]

page 27

How many kinds of Attraction are there?

59. There are two kinds of attraction namely, the Attraction of Gravitation and the Attraction of Cohesion. (See par. 1388.)

The former belongs to all matter, whatever its form, thelatter appears to belong principally to solid bodies.

What is the Attraction of Gravitation?

60. The Attraction of Gravitation is the reciprocal attraction of separate portions of matter.

What is the Attraction of Cohesion?

61. The Attraction of Cohesion is that when causes the particles of a body to cohere together.
62. The attraction of cohesion appears to exist but in a very slight degree, if at all, in liquids and fluids.

Exemplify the two kinds of Attraction, namely Gravity and Cohesive Attraction?

63. The attraction of gravitation causes a body, when unsupported, to fall to the ground. The attraction of cohesion holds together the particles of a body and causes them to unite in masses.*

* Besides these two kinds of attraction, there seem to be other kinds of attractive force, active in vegetation and in animal life, known by the names of Endosmose and Exosmose, terms applied to the transmission of

gaseous matter or vapors through membranous substances. See note to Capillary Attraction, under the head, of Hydrostatics, on page 112.

Other kinds of attraction, called Electrical and Magnetical Attraction, will hereafter be considered under their appropriate head. The subject of Chemical Attraction or Affinity belongs distinctly to the subject of Chemistry and will not, therefore, be considered in this work.

64. Having described the essential properties of bodies, we come now to the consideration of other properties belonging respectively to different kinds of matter; such as Porosity, Density, Rarity, Compressibility, Expansibility, Mobility, Elasticity, Brittleness, Flexibility, Malleability, Ductility, Tenacity.
65. It has already been stated that matter consists of minute particles or atoms, united by different degrees of cohesive attraction.

These atoms are probably of different shapes in different bodies, and the different degrees of compactness with which they unite give rise to certain qualities, which differ greatly in different substances.

These qualities or properties are described under the names of Porosity, Density and Rarity, which will presently be described.

page 28

66. Besides the property of attraction possessed by the particles or atoms of which a body is composed, there seems to be another property, of a nature directly opposite to attraction, which exerts itself with a repulsive force, to prevent a closer approximation of the particles than that which by the law of their nature they assume.

This property is called repulsion. This repulsion prevents the particles or atoms from coming into perfect contact, so that there must be small spaces between them, where they do not absolutely touch one another. [See Figure 1st.] These spaces are called pores, and where they ex1ist give rise to that property or quality described under the name of Porosity.

What is Porosity?

67. POROSITY. Porosity implies, therefore, that there are spaces, or pores, between the particles or atoms which form the mass of a body.
68. DENSITY. „When the pores are few, so that a large number of particles unite in a small mass, the body is called a dense body.

What is Density?

69. Density, therefore, implies the closeness or compactness of the particles which compose any

substance.

70. RARITY. When the pores in any substance are numerous, so that the particles which form it touch one another in only a few points, the body is called a rare body.

What is Rarity?

71. Rarity, therefore, is the reverse of density, and implies extension of bulk without increase in the quantity of matter.
72. From what has now been stated it appears [See No. 67] that the particles of a body are connected together by a system of attractions and repulsions which give rise to distinctions which have already been described. It remains to be stated that these attractions and repulsions differ much in degree in different substances, and this difference gives rise to other properties, which will now be explained, under their appropriate names.
73. COMPRESSIBILITY. When the repulsion of the particles of any substance can be overcome and the mass can be reduced within narrower limits of extension, it is said to possess the property of Compressibility *

* Compressibility differs from Contractibility rather in cause than in effect. Contractibility implies a change of bulk caused by change of temperature, or any other agency not mechanical. Compressibility implies that the diminution of bulk is caused by some external mechanical force.

page 29

What is Compressibility?

74. Compressibility, therefore, may be defined, the susceptibility of a reduction of the limits of extension.
75. This property is possessed by all known substances, but in very different degrees, some substances requiring but little force to compress them, others resisting very great forces, but it is not known that there is any substance unsusceptible of compression, if a sufficient force be applied. *

* Sir Isaac Newton conjectured that if the earth were so compressed as to be absolutely without pores, its dimensions might not exceed a cubic inch.

76. Liquids in general are less easily compressed than solid bodies, so much so, indeed, that in practical science they are generally considered as incompressible. Under a very considerable mechanical force, a siight degree of compression has been observed. **

**Under a pressure of fifteen pounds on a square inch, water has been diminished in bulk only by about forty-nine parts in a million. Under a pressure of fifteen thousand pounds on a square inch, it was compressed by about one-twentieth of its volume. The experiment was tried in a cannon, and the cannon was burst.

77. EXPANSIBILITY. The system of attractions and repulsions among the particles of a body are sometimes so equally balanced that they exist, as it were, in an equilibrium. In other cases the repulsive energy is so great as to predominate when the attractive force is unaided. When the repulsive energy is permitted to act without restraint, it forces the particles asunder and increases the limits of extension, giving rise to another property of matter possessed by many bodies, but in an eminent degree by matter in a gaseous form. This property is called Expansibility.

What is Expansibility?

78. Expansibility, *** therefore, may be defined as that property of matter by which it is enabled to increase its limits of extension.

*** Expansibility and Dilatability are but different names for the same property, but expansion implies an augmentation of the bulk or volume, dependent on mechanical agency, while dilatation expresses the same condition produced by some physical cause not properly falling under the denomination of mechanical force. Thus heat dilates most substances, while cold contracts them. It is on this principle that the thermometer is constructed. [See page 149, No. 546.]

All gaseous bodies are invested with the property of dilatability to an unlimited degree, by means of which, when unrestrained, they will expand spontaneously, and that without the application of any external agency a degree to which there is no known limit.

79. ELASTICITY. When the atoms or particles which constitute a body are so balanced by a system of attractions and repulsions that they resist any force which tends to change the figure of the body, they will possess another property, known by the name of Elasticity.

page 50

What is Elasticity?

80. Elasticity, therefore is the property which causes a body to resume its shape after it has been compressed or expanded.*

* This property is possessed, in at least some small degree, by all substances, or, at least, it cannot be said that any substance is wholly destitute of elasticity. Even water and other liquids, which yield with difficulty to compression, recover their volume with a force apparently equal to the compressing force. But, for most practical purposes, many substances, such as putty, wet paste, moist paper, clay, and similar bodies, afford examples of substances possessing the property of elasticity in so slight a degree that they are treated as non-elastic bodies.

81. Thus, when a bow or a steel spring is bent, its elasticity causes it to resume its shape.
82. India rubber (or caoutchouc) possesses the property of elasticity in a remarkable degree, but steam and other bodies in a gaseous form in a still greater.**
83. Ivory is endowed with the property of elasticity in a remarkable degree, but exhibits it not so much by the mere force of pressure, out it requires the force of impact to produce change of form.***

What is Brittleness?

84. BRITTLENESS. Brittleness implies aptness to break.

** The gases or aeriform bodies afford the most remarkable instances of elasticity. When water is converted into steam it occupies a space seventeen hundred times greater than the water from which it is formed, and its elasticity causes it to expand to still larger dimensions on the application of heat. It is this peculiar property of steam, modified, as will be explained in a future part of this work, which is the foundation of its application in the movement of machinery. All gaseous bodies are equally elastic.

*** The metals which are best adapted to produce sound are those which are most highly elastic. It sometimes happens that two metals, neither of which have any great degree of hardness or elasticity, when combined in certain proportions, will acquire both of these properties. Thus tin and copper, neither of which in a pure state is hard or elastic, when mixed in a certain proportion, produce a compound so hard and elastic that it is eminent for its sonorous property, and is used for making bells, &c

Brittleness and hardness are properties which frequently accompany each other, and brittleness is not inconsistent with elasticity. Thus glass, for instance, which is the most brittle of all known substances, is highly elastic. The same body may acquire or be divested of its brittleness according to the treatment which it receives. Thus iron, and some other metals, when heated and suddenly plunged into cold water, become brittle; but if, in a tested state, they are buried in hot sand, and thus be permitted to cool very gradually, they will lose their brittleness and acquire the opposite quality of flexibility. This process in the arts is called annealing.

page 31

What is Flexibility?

85. FLEXIBILITY. Flexibility implies a disposition to yield without breaking when bent.

What is Malleability?

86. MALLEABILITY. Malleability implies that property by means of which a body may be reduced to the form of thin plates by means of the hammer or the pressure of rollers.
87. This property is possessed in an eminent degree by some of the metals, especially gold, silver, iron and copper, and it is of vast importance in the arts. A knowledge of the uses of iron, and of its malleability, is one of the first steps from a savage to a civilized state jf life.
88. The most malleable of the metals is gold, which may be hammered to such a degree of thinness as to require three hundred and sixty thousand leaves to equal an inch in thickness.*

* The malleability of the metals varies according to their temperature. Iron is most malleable at a white heat. Zinc becomes malleable at the temperature of 300 ° or 400°. Some of the metals, and especially antimony, arsenic, bismuth and cobalt, possess scarcely any degree of this property.

The familiar process of welding is dependent on malleability. The two pieces of metal to be welded are first heated to that temperature at which they are most malleable, and, the ends being placed together, the particles are driven into such intimate connexion by the welding-hammer that they cohere. Different metals may in some cases be thus welded together.

89. DUCTILITY. Some substances admit of being extended simultaneously both in length and breadth. Others can both extended to a greater degree in length alone, and this property gives rise to another name, called Ductility.

What is Ductility?

90. DUCTILITY. Ductility is that property which renders a substance susceptible of being drawn out into wire.
91. The same metals are not always both ductile and malleable to the same degree. Thus iron may be beaten into any form, when heated, but not into very thin plates, but it can be drawn into extremely fine wire. Tin and lead, on the contrary, cannot be drawn out into small wire, but they are susceptible of being beaten into extremely thin leaves.

page 32

92. Gold and platinum have a high degree both of ductility and malleability. Gold can be beaten (as has already been stated) into leaves so thin that it would require many thousands of them to equal an inch in thickness. It has also been drawn into wire so attenuated that one hundred and eighty yards of it would not weigh more than a single grain. An ounce of such wire would be more than fifty miles in length. But platinum can be drawn even to a finer wire than this.

What is Tenacity?

93. TENACITY. Tenacity implies the cohesion of the particles of a body.
94. Tenacity is one of the great elements of strength. It is the absence of tenacity which constitutes brittleness. Both imply strength, but in different forms. Thus glass, the most brittle of all substances, has a great degree of tenacity. A slender rod of glass, which cannot resist the slightest lateral pressure, if suspended vertically by one end will sustain a very considerable weight at the other end.*

* A knowledge of the tenacity of different substances is of great use in the arts. The tenacity of metals and other substances has been ascertained by suspending weights from wires of the metals, or rods and cords of different materials.

The following table presents very nearly the weights sustained by wires of different metals, each having the diameter of about one-twelfth of an inch.

Lead                             27 pounds                                            Silver                            187 pounds

Tin                                34                                                          Platinum                      274

Zinc                              109                                                        Copper                         302

Gold                             150                                                        Iron                               549

Cords of different materials, but of the same diameter, sustained the following weights:

Common flax              1175 pounds                                       New Zealand flax        2380 pounds

Hemp                           1633                                                      Silk                                3400

The following table presents a more extended list of materials. The area of a transverse section of the rods on which the experiment was tried was one square inch.

Pounds Avoirdupois.                                                          Pounds Avoirdupois

English Oak                 8,600 to 12,000         Tin                                                          7,129

Fir                                 11,000                         Lead                                                      3,146

Beech                          11,500                         Rope, 1 inch in

Mahogany                   8,000                                        circumference                        1,000

Teak                             15,000                         Whale line, 2 inches,

Cast Steel                    134,256                                    in circumference

Iron Wire                    93,964                                      spun by hand                          2,240

Swedish Bar-iron       72,064                         Do., by machinery                               3,520

Cast-iron                      18,655                         Rope, 3 inches

Wrought Copper    33,792                                      in circumference                   5,628

Platinum Wire         52,987                         Do., 4 inches                                     9,988

Silver Wire                38,257                         Cable, 141 inches                            89,600

Gold                            30,888                         Do., 23 inches                                   255,360

Zinc                              22,551

 

 

A more particular account of the tenacity of various substances will be found in Barlow’s Essay on the Strength of Timber, Rennie’s Treatise (in Phil. Trans. 1818), Tredgold’s Principles of Carpentry, and the 4th vol. of Manchester Memoirs, by Mr. Hodgkinson.

 

page 33

95. The tenacity of metals is much increased by uniting them. A compound consisting of five parts of gold and one of copper has a tenacity of more than double that of the gold or copper alone; and brass, which is composed of copper and zinc, has a tenacity more than double that of the copper, and nearly twenty times as great as that of the zinc alone. A mixture of three parts of tin and one of lead has a tenacity more than double that of the tin; and a mixture of eight parts of lead and one of zinc has a tenacity nearly double that of the zinc, and nearly five times that of the lead alone.*

* There are many other specific properties of bodies besides those that have now been enumerated, the consideration of which belongs to the science of Chemistry.

>> forward >>