Chemical agent

“ The view long maintained—until late in the nineteenth century, in fact—that organic and inorganic chemistry are separated from each other by a wide gap, is no longer held. Hundreds of organic substances, some of them of great complexity, have been made in the chemist’s laboratory, and can now be classed as properly with inorganic as with organic substances. The gap has been closed, and there is now but one chemistry. Only the most intricate chemical compounds still lie beyond the chemist’s grasp, and the isolation of these may be at any time overthrown. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ They absorb oxygen from the surrounding medium, air or water, and, in addition to certain inorganic substances, take into their bodies, as their proper nutritive material, complicated protein compounds, which they derive either directly or indirectly from plants. Through the oxidation of these compounds they form substances of a simpler chemical structure, such as carbonic acid, water, and ammonia, and discharge these through their bodies as waste. ”

“ 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 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. ”

“ The mysteries of organic chemistry are great, and the differences between its processes or reactions as they are carried out in the organism and in the laboratory are many421. The actions, catalytic and other, which go on in the living cell are of extraordinary complexity. But the contention that they are different in kind from what we term ordinary chemical operations, or that in the production of single asymmetric compounds there is actually to be witnessed, as Pasteur maintained, a “prerogative of life,” would seem to be no longer safely tenable. ”

“ 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. ”

“ But we are not to infer that they are destitute of medicinal powers, because they possess no sensible properties. In their chemical composition, they have hitherto shewn but few ingredients; and those of the simpler saline substances, common to most mineral springs. [43] It does [130] not follow, however, that they contain no active materials because chemistry is not able to detect them. Powerful agents may be diffused in waters, and which are incapable of analysis, or destructible by the process employed for that purpose. The only sure test is experience of their effects on the human body. ”

“ So the synthesis of a single organic compound sufficed at a blow to break down the chemical barrier which the imagination of the fathers of the science had erected between animate and inanimate nature. Thenceforth the philosophical chemist would regard the plant and animal organisms as chemical laboratories in which conditions are peculiarly favorable for building up complex compounds of a few familiar elements, under the operation of universal chemical laws. ”

“ 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. ”

“ 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 ”

“ To neglect this is as serious an omission for such students as for chemists would be the neglecting to determine whether it is nitrogen or hydrogen, urea or stearine, that has been extracted from a tissue, or which it is whose combinations they are studying in this or that chemical operation. Now, scarcely any one of those who study fermentations, properly so-called, and putrefactions, ever pay any attention to the preceding data. ... ”

“ Our chemists found that starting with simple substances they could, by proper means, combine them into molecules of greater complexity, and in so doing could make many of the compounds that had hitherto been produced only as a result of living activities. For example, urea, formic acid, indigo, and many other bodies, hitherto produced only by animals and plants, were easily produced by the chemist by purely chemical methods. ”

“ There he pursued with ardour and success chemical investigations which placed him among the first chemists of his time. One of his earliest results was the discovery of a method of determining the nitrogen in organic compounds difficult to burn. ”

“ How might NH4Cl be obtained from the NH4OH in the Woulff bottles? (6) Test the liquid in each bottle with red litmus paper. (7) Add some from the first bottle to 5 or 10 cc. of a solution of FeSO4 or FeCl2, and look for a ppt. State the reaction.
99. Formation.—Ammonia, hartshorn, exists in animal and vegetable compounds, in salts, and, in small quantities, in the atmosphere. Rain washes it from the atmosphere into the soil; plants take it from the soil; animals extract it from plants. Coal, bones, horns, etc., are the chief sources of it, and from them it is obtained by distillation. ”

“ 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 Same Elements found in Plants and Animals as in their Environment.—It has been found by chemists that the plants and animals as well as their environment may be reduced to about eighty very simple substances known as chemical elements. For example, the air is made up largely of two elements, oxygen and nitrogen. Water, by means of an electric current, may be broken up into two elements, oxygen and hydrogen. The elements in water are combined to make a chemical compound. The oxygen and nitrogen of the air are not so united, but exist as separate gases. ”

“ As a matter of fact, it can be shown that it is to the purely scientific chemist, working with the main object of building up the science, that we owe the discovery of most valuable remedies, at least of those which are strictly speaking chemical compounds. I select for this purpose two substances which have but comparatively recently found their places in the materia medica—viz., chloral and salicylic acid. How and by whom were these substances discovered and introduced into medicine? ”

“ The putrefaction of animal and other azotized bodies is a chemical process, by which they are gradually dissipated in a gaseous form, chiefly in that of carbonic acid and ammonia; now to convert the carbon of the animal substance into carbonic acid requires oxygen, and to convert the azote into ammonia requires hydrogen, which are the elements of water. ”

“ In the lectures and recitations a systematic study of the aliphatic and aromatic compounds is undertaken. In the laboratory certain selected experiments in the analysis and synthesis of organic compounds is carried out as well as exercises in the study of the chemical properties of various classes of compounds. The course is conducted with special reference to the industrial applications of organic chemistry. Some of the newer physico-chemical tools used in the study of the science will be considered. ”

“ A mixture which will destroy micro-organisms and yet will not destroy a living cell certainly shows a fine sense of selection and discrimination not heretofore expected of a combination of chemicals or of a chemical compound. How like the wonderful elixir of medieval times, which was to the Christian a tonic and to the heathen a poison!
Here is another claim made for this nostrum:
“Two or three rectal injections of a one or two per cent. ”

“ As a rule, the key-note of the action of these agents, if I may use such a simile, is through one particular element where many elements enter into their composition. Where nitrogen is present as an element, a definite line of action of the agent is marked out; when a hydrocarbon radical is dominant—that is to say, when such a radical forms the chief part of the compound—the influence of that is most definite; while the influence of one disturbing principle on another may be most clearly traced in other cases as a neutralizing influence, one influence reacting upon the other. ”

“ The value of certain chemical compounds as artificial manures is fully recognised, yet many attempts are being made to prove the value of other substances for the same purpose, with a view to increase in efficiency and decrease in cost. ”

“ Chemical Composition. In all the varieties the predominant principles are tannin and extractive. Solubility. The best menstruum is diluted alcohol. Incompatible Substances, vide Gallæ. Mr. Thomson also states a fact which I have reason to consider quite correct, that the alkalies destroy the astringent properties of kino. All the varieties are soluble in solutions of pure potass and ammonia, and no precipitation takes place on the addition of water. Medicinal Uses. ”

“ Taste, bitterish and heavy. Chemical Composition. Resin combined with volatile oil, and a mucilaginous extractive matter, with small portions of albumen, gelatine, muriate of ammonia, and phosphate of soda. Solubility. Boiling water dissolves it perfectly; rectified spirit takes up most of its active parts, although the odour is only discovered upon dilution; sulphuric æther is its most complete menstruum. Incompatible Substances. The solutions are decomposed by Oxy-muriate of Mercury; Sulphate of Iron; Nitrate of Silver; and the Infusion of Yellow Bark. Med. Uses. Stimulant and antispasmodic. ”

“ Expert Analysis.—A modification of this experiment is employed by experts to test for AS2O3 poisoning. The organs.— stomach or liver—are cut into small pieces dissolved by nascent Cl, or HClO, made from KC1O3 and HCl, and the solution is introduced into a H generator, as above. AS2O3 preserves the tissues it comes in contact with, for a long time, and the test can be made years after death. All the chemicals must be pure, since As is found in small quantities in most ores, and the Zn, HCl, and H2SO4 of commerce are very likely to contain it. ”

“ In organic as in inorganic chemistry, atoms are bound together by chemical affinity, though it was formerly supposed that an additional or vital force was instrumental in forming organic compounds. For this reason none of these substances, it was thought, could be built up in the laboratory, although many had been analyzed. In 1828 the first organic compound, urea, was artificially prepared, and since then thousands have been synthesized. They are not necessarily manufactured from organic products, but can be made from mineral matter. ”

“ The facility with which chemical inquiries are carried on, and the simplicity of the apparatus, offer additional reasons, to those I have already given, for the pursuit of this science. It is not injurious to the health; the modern chemist is not like the ancient one, who passed the greater part of his time exposed to p. 174the heat and smoke of a furnace and the unwholesome vapours of acids and alkalies and other menstrua, of which, for a single experiment, he consumed several pounds. ”