Chemical substance

“ The results of the experimental examination of the compositions and properties of substances, made since the time of the alchemists, have led to the modern conception of the chemical element, and the isolation of about seventy or eighty different elements. No substance now called an element has been produced in the laboratory by uniting two, or more, distinct substances, nor has any been separated into two, or more, unlike portions. ”

“ This explains why salts are usually inactive and neutral in character, while acids and bases are active agents. Thus we see why the most positive or the most negative elements in general have the strongest affinities, while those intermediate in the list are inactive, and have weak affinities; why alloys of the metals are weak compounds; why a neutral substance, like water, has such a weak affinity for the salts which it holds in solution; and why an aqueous solution is regarded as a mechanical mixture rather than a chemical compound. ”

“ Chemical Elements in the Body. All of the various complex substances found in nature can be reduced by chemical analysis to about 70 elements, which cannot be further divided. By various combinations of these 70 elements all the substances known to exist in the world of nature are built up. When the inanimate body, like any other substance, is submitted to chemical analysis, it is found that the bone, muscle, teeth, blood, etc., may be reduced to a few chemical elements. ”

“ The student will thus be brought to the chemical conception of the molecule as the smallest mass of any substance in which the qualities inhere, and he will come to regard a chemical process as always taking place between molecules.
Thus far nothing has been said about the composition of matter. A chemical process has been defined simply as certain factors yielding certain products, but nothing has been determined about the relations of these several substances except in so far as they are defined by the three laws illustrated above. ”

“ This is only a simple case; but the chemical laws which govern it hold equally well for every known substance found in nature. There are only about seventy-five known elements, and of these less than thirty compose the majority of the things found in every-day life. ”

“ Test for a Carbonate.—To test for a carbonate, treat the substance with an acid; CO2 is formed; pour the gas into a solution of lime-water, and a white insoluble precipitate is formed, CaCO3.
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TABLE OF ALL THE KNOWN CHEMICAL ELEMENTS The Chemical Elements are the simplest known constituents of all compound substances. Chemists regard them as elements or elementary substances only when they have been proved to be not compound. The elements are somewhat arbitrarily divided into metals and non-metals, the former constituting by far the larger class. ”

“ Chemistry plays a part in every phase of life; in the arts, the industries, the household, and in the body itself, where digestion, excretion, etc., result from the action of the bodily fluids upon food. The chemical substances of most interest to us are those which affect us personally rather than industrially; for example, soap, which cleanses our bodies, our clothing, our household possessions; washing soda, which lightens laundry work; lye, which clears out the drain pipe clogged with grease; benzine, which removes stains from clothing ”

“ The synthesis of other so-called organic compounds followed, and at present it is known that the same chemical laws apply to all substances whether formed in the living organism or prepared in the laboratory from inorganic constituents. ”

“ The fundamental task of inorganic chemistry is still connected with the classification of elements and compounds. The investigation of the classification of carbon compounds forms the field of organic chemistry; while general or physical chemistry deals with the laws of reaction, and the influence of various forms of energy in furthering or hindering chemical change. ”

“ The first class includes such substances as iodine, mercury, iron, carbon, and their various compounds, and such bodies as alcohol, chloroform and chloral, all of which are found in nature or can be prepared by ordinary chemical processes of manufacture. From plants many substances are obtained which at the present time we are unable to make in the chemical laboratory, and of the constitution or composition of which we are in many cases ignorant. ”

“ After becoming acquainted with the constituent elements of all the substances within our reach and the mutual relations of these elements, the remarkable transmutations to which the bodies are subject under the influence of the vital powers of plants and animals, became the principal object of chemical investigations, and the highest point of interest. A new science, inexhaustible as life itself, is here presented us, standing upon the sound and solid foundation of a well established inorganic chemistry. ”

“ The peculiar manner in which hydrogen gas appears to dissolve solid substances,—as iron, potassium, sodium, sulphur, phosphorus, selenium, and arsenic, may be explained by regarding the results as a manifestation of the powers of chemical affinity over the forms of bodies. In like manner, the solution of salt in water, or the mixture of alcohol in that fluid, may be viewed as chemical phenomena, although usually considered as simple cases of solution or mixture: alterations of temperature and other physical changes taking place in either. ”

“ The molecule of an element usually contains two atoms; that of a compound may have two, or it may have hundreds. For a given compound the number is always definite.
Chemism is the force that binds atoms together to form molecules. The sugar molecule contains atoms, forty-five in all, of three different elements: carbon, hydrogen, and oxygen. That of salt has two atoms: one of sodium, one of chlorine. Should we say "an atom of sugar"? Why? Of what is a mass of sugar made up? A molecule? A mass of carbon? A molecule? Did the chemical affinity of the acid break up masses or molecules? ”

“ Organic compounds, on which our life and living depend, consist chiefly of four elements: carbon, hydrogen, oxygen and nitrogen. These compounds are sometimes hard to analyze, but when once the chemist has ascertained their constitution he can usually make them out of their elements—if he wants to. He will not want to do it as a business unless it pays and it will not pay unless the manufacturing process is cheaper than the natural process. ”

“ When this element, nitrogen, is combined with the wonderful variety of compounds formed by carbon, we have not only a great many intimately related yet distinct [100] substances, but compounds which readily change from one form to another. These are the distinctive qualities or conditions necessary, from a chemical standpoint, to make the processes of life possible. Protoplasm, which is the basis of all life, is formed by an intimate mixture of a number of complex chemical compounds, the chief elements of which are carbon, hydrogen, oxygen, and nitrogen. ”

“ It brings home to me what an unstable chemical compound man is. Here are the stage accessories as good as ever, while the players have all split up into hydrogen and oxygen and nitrogen and carbon, with traces of iron and silica and phosphorus. ”

“ The elements which play important parts in organic compounds are carbon, hydrogen, nitrogen, chlorine, bromine, iodine, sulphur, phosphorus and oxygen. We shall here consider the qualitative and quantitative determination of these elements.
Qualitative.—Carbon is detected by the formation of carbon dioxide, which turns lime-water milky, and hydrogen by the formation of water, which condenses on the tube, when the substance is heated with copper oxide. Nitrogen may be detected by the evolution of ammonia when the substance is heated with soda-lime. ”

“ Take the case of elective affinity, which, by its very title, gives to these so-called dead substances the property of a power of choosing. As an example of what I mean generally let me remind you of a very common mineral, chalk, or carbonate of lime; in it a solid substance, lime, is combined with a colourless gas called carbonic acid. Now, the instant that another acid, say sulphuric acid, is brought in contact with chalk, what is the result? ”

“ The subject of Organic Chemistry is that to which, at the present day, the eyes of all thinking members of the profession are directed, and upon which their hope of progress mainly depends,—the relations of chemical action to the functions of organized matter, the application of chemistry to physiology and pathology, are to be treated of as fully as present knowledge extends. ”

“ C. Every liquid which, when placed in a white porcelain vessel to the depth of one inch, exhibits under daylight distinct color.
D. Every liquid which contains in solution, in every 100,000 [8] parts by weight, more than two parts of any metal, except calcium, magnesium, potassium and sodium.
E. Every liquid which in every 100,000 parts by weight contains in solution, suspension, chemical combination or otherwise, more than 0.5 metallic arsenic.
F. Every liquid which, after the addition of sulphuric acid, contains in every 100,000 parts by weight more than one part of free chlorine. ”

“ But as soon as the solution is rendered stronger, or the solvent and the dissolved body are endowed with a mutual chemical affinity, chemical reactions set in. Part of the molecules of the dissolved body dissociate, and the atoms of which they were composed, on being set free, combine with the atoms of the solvent. Chemical forces, much more energetic than the physical forces, enter into play, and most complicated chemical reactions—the intensity of which may be judged of from the changes of temperature—begin. ”

“ The chemical elements include oxygen, silicon, calcium, sulfur, carbon, gold, silver, and many others. There are 90 naturally occurring elements. Each is made up of molecules that consist of only one kind of atom. Chemical elements may either be combined with each other or occur alone. They are the building blocks of our world for they make up all the gases, all the liquids, all the minerals, all the plant and animal life, and all the other physical matter. Some of the chemical elements that occur in the rocks and minerals mentioned in this book are listed below. ”

“ Other organic compounds which contain tetravalent oxygen are exceedingly active chemically, and there seems to be much to commend this view of the chemical structure of the water molecule.
Probably the most remarkable property of water is its power of solution. No other liquid surpasses water as a solvent. ”

“ When oxygen combines with a single element, what is the compound called? We have found that O makes up a certain portion of the air; later, we shall see how large the proportion is. Its tendency to combine with almost everything is a reason for the decay, rust, and oxidation of so many substances, and for conflagrations, great and small. New compounds are thusformed, of which O constitutes one factor. Water, H2O, is only a chemical union of O and H. Iron rust, Fe2O3 and H2O, is composed of O, Fe, and water. The burning of wood or of coal gives rise to carbon dioxide, CO2, and water. ”

“ It is not impossible but that the coats of their stomachs may be, in some measure, tanned, or hardened by the constant use of this liquor; but you must remember that where a number of other chemical agents are concerned, and, above all, where life exists, no certain chemical inference can be drawn. ”

“ May we not, therefore, conclude that the chemical action exhibited in a burning body is a development of some latent force, with which we are unacquainted, produced by the absorption of light;—that a repulsive action at first takes place, by which the hydrogen and carbon are separated from each other;—and that in the nascent state they are seized by the oxygen, and again compelled, though in the new forms of water and carbonic acid, to resume their chains of combining affinity? ”

“ Water, from its extensive powers as a solvent, never occurs in a state of absolute purity, although the nature and degree of its contamination must necessarily vary according to circumstances and situation. It is generally found holding earthy matter in a state of mechanical suspension, or saline and other bodies in chemical solution. ”

“ Organic Compounds.—Substances whose highly complex and very unstable molecules are composed of those of chemical elements, inorganic compounds, or organic compounds of lower organization: formed on the cooled surfaces of fully developed planets at life-supporting temperatures. ”

“ Thus we find 'inflammable air* as the name for hydrogen, 'fixed air* for carbonic acid gas, and 'dephlogisticated marine acid air' for chlorin. That no better principle of classification of substances from a chemical standpoint than that of superficial outward appearance was demanded is not strange, when we recollect that at this period and, indeed, down to the close of the eighteenth century, the transmutation of metals was a popular belief of the common people and was not disproved by the chemist. ”

“ To take a simple example:—oxygen and hydrogen are two gases which may be mixed in all proportions at ordinary temperatures, and it is easy to show that the properties of the products are simply those of mixtures of the two free gases. If, however, an electric spark be passed through the mixtures, powerful chemical union ensues, with its concomitants, great evolution of heat and consequent rise of temperature, and a compound, water, is formed which presents physical and chemical properties entirely different from those of its constituents. ”