Chemistry of Things Familiar
What is Starch?—How Manufactured?—Composition of Wheat Flour—Acids—Alkalies—Sulphuric, Nitric, and Muriatic Acids—Sulphuretted Hydrogen—Tanning of Hides to Form Leather—Vinegar—Alcohol—Yeast—Fruit, How Preserved—Decay in Wood—What is Ether?—Disinfecting Agents—How Smoking Preserves Meat—What is Albumen?—What is a Poison?—Arsenic—Certainty of its Detection—Lead Pipes, How Poison Water—Verdigris—Calomel—Preservation of Wood—Common Names of Chemicals
What is starch?
The name starch is given to a mealy substance which is deposited in most vegetables at the time of ripening, from the juices with which the cells of the plants are filled.
What common vegetable especially abounds in starch?
The potato, which consists entirely of cells filled with starch and water.
A cell is a little membranous bladder filled with a solid or fluid substance.
Why does a laundress find it necessary to boil starch before using it for stiffening linen, etc.?
The starch, consisting of little granules, is insoluble in cold water; but when acted upon by hot water, the granules burst and allow their contents, which are soluble, to become mingled with the water.
Starch is manufactured as follows:—
Potatoes, for example, from which most of the starch of commerce is manufactured, after being pared, are grated to a pulp. This pulp is put upon a sieve and stirred about, while at the same time a little stream of water is made to flow upon it. A milky liquid runs through the sieve, but the fibrous portion of the potato, the vegetable tissue, remains behind. This liquid, after a short interval, deposits a white powder, which is the starch. By the simple process of tearing up the vegetable tissue, and removing the inclosed starch by washing, this substance may be procured from a great variety of plants.
Why do potatoes, beans, rice, and most of the common vegetables, swell up when boiled with water?
Because the starch absorbs water at the boiling temperature, which causes the cells to swell, thereby giving to the vegetable a rounded appearance.
What is the composition of wheat flour?
Starch is one of the principal constituents of wheat flour, as well as of all other kinds of meal. The other principal constituent is a gray, tough, viscous substance, called gluten.
To what does paste, made of wheat or rye flour, owe its adhesiveness?
In some measure to the starch, but principally to the gluten contained in it.
Can starch be converted into gum and sugar?
It can; fruits and plants effect this change naturally: we can also produce the change artificially by chemical processes.
Why are potatoes frozen and thawed sweet?
Because by the freezing action the starch of the potato is in part converted into sugar.
Why are apples, pears, grapes, etc., in their unripe state sour, and in their ripe condition sweet?
In the unripe fruits mentioned starch is present; in the ripe fruits it is absent; in the process of ripening the starch is converted into sugar, and the fruit becomes sweet.
What are acids?
Acids are substances which excite the taste of sourness when applied to the tongue; they change the blue juices of vegetables to red, and combine with alkalies to form neutral compounds.
What is an alkali?
An alkali is a body that possesses properties the converse of those of an acid. It has a highly bitter, acrid taste, changes the blue juices of vegetables to green, or the juices of vegetables which have been changed red by an acid, back again to blue. Potash and soda are the representatives of the alkalies.
When sulphur is burned in the air what is the product formed?
Sulphurous acid.
What causes the suffocating odor of a lighted brimstone match?
The sulphurous acid generated by the combustion of the sulphur.
What is sulphuric acid or oil of vitriol?
It is a compound of sulphur and oxygen, containing one-third more oxygen than sulphurous acid.
What is sulphuretted hydrogen?
A gas formed by the union of sulphur and hydrogen. It possesses an offensive odor, and is very poisonous.
How is sulphuretted hydrogen formed in nature?
Principally from the decomposition of animal substances, as blood, flesh, hair, etc.
Why does the yolk of an egg tarnish a silver spoon?
Because it contains a little sulphur, which, at the temperature of an egg just boiled, will decompose the water or moisture upon the spoon, and produce sulphuretted hydrogen gas, which will tarnish silver.
Both the white and the yolk contain sulphur, but the latter the most abundantly.
What is it that makes an open or foul sewer so destructive of health to any district in which it may be situated?
The evolution of sulphuretted hydrogen. When inhaled, it acts directly upon the blood, thickening it, and turning it black.
Why do surfaces painted with lead paints, in the vicinity of sewers, soon turn black, or become discolored?
Through the action of sulphuretted hydrogen.
What is nitric acid?
Nitric acid, or aqua-fortis, is a compound of five parts of oxygen and one of nitrogen.
It is liquid; when pure, colorless, and highly corrosive; it attacks almost all dead, unorganized substances, and destroys living tissues.
What is muriatic, or, more properly, hydrochloric acid?
A compound of hydrogen and chlorine usually prepared from salt. It is an acid much used in the arts.
What is “lunar caustic”?
A compound of nitric acid and oxide of silver.
Why, when lunar caustic is applied to the flesh, does it burn and destroy it?
Through the agency of the nitric acid contained in it.
Do plants produce acids?
Acids are formed in the vegetable kingdom in great abundance; they especially exist in unripe fruits, imparting to them a sour taste.
Acids formed from mineral substances are called “mineral acids”; acids formed by or from vegetable substances are called “organic acids.”
Why does tanning hides convert them into leather?
Hides are steeped in water, with ground bark of the oak, hemlock, or other trees; these barks contain large quantities of tannic acid, which combine with the skin of animals, and form a combination which is insoluble in water and not subject to putrefaction—viz., leather.
What is ordinary vinegar?
An acid, called acetic acid, and water.
If wine or beer be imperfectly corked, why does it rapidly turn sour?
Because air gets into the liquor, and the oxygen of the air combining with the alcohol of the liquor produces acetic acid, or vinegar.
What is alcohol?
Alcohol is the spirit existing in wine, beer, cider, etc., obtained in the process of fermentation.
What is a ferment?
A ferment is a substance containing nitrogen in a state of decomposition, which is able to excite fermentation in solutions of sugar; old cheese, putrefying flesh, blood, etc., all of them are ferments.
What is yeast?
We apply the term yeast to a particular species of ferment; the foam of beer (or of some similar liquor), produced by fermentation.
Can you explain why it is that a body in a state of fermentation or putrefaction should cause unlimited quantities of similar matter to pass into the same state?
We only know the fact: the reason we are ignorant of. The most minute portion of milk, paste, juice of grapes, flesh, or blood, in a state of fermentation or putrefaction, causes fresh milk, paste, grape juice, flesh, or blood, to pass into the same condition, when in contact with them.
In storing or packing fruit for future use why is it necessary to carefully remove every decayed specimen?
Because the decayed portions of one specimen will quickly communicate decay to the fresh fruit in contact with it, and soon the whole mass of fruit will become putrescent.
If in a vessel, or any other structure, one timber becomes decayed what course ought to be adopted?
It should be removed immediately, or the decomposition once commenced will in time affect the whole structure.
It sometimes happens that physicians, in dissection, are seriously poisoned by the slightest cut of a knife which has been used upon the dead body. The knife introduces to the healthy blood, through the wound, a minute portion of matter in the state of decomposition or putrefaction. This acts as a ferment, and causes the healthy matter in contact with it to pass into the same decomposed state. The action once commenced rapidly extends, until the whole body becomes affected, and death ensues. It is almost impossible to heal wounds of this character.
Why is it especially dangerous to eat fruit or meats partially decayed?
Because the decayed portions of the substance eaten are liable to induce the same condition in the healthy organs of the stomach with which they may come in contact.
Why do fruit preserves frequently turn sour?
Because, owing to the action of some fermenting substance present either in the fruits themselves or in the air, the sugar used in preserving is converted into alcohol, and the alcohol into vinegar.
Why does the housewife scald her preserved fruits to prevent their turning sour?
Because fermenting substances and fermenting action are destroyed by a boiling temperature.
Why do we keep preserves, beer, cider, or other substances liable to turn sour, in a cool place?
Because a depression of temperature arrests fermentation, though it does not prevent its renewal when the temperature in increased.
What is ether?
Ether is a product obtained by distilling strong alcohol and sulphuric acid. The product is called sulphuric ether, but it does not contain sulphuric acid, nor has it any sulphur in its composition.
What are the properties of ether?
It is an exceedingly volatile, inflammable body, producing insensibility when inhaled, and readily dissolving all fatty and oily bodies.
Why will ether remove spots of oil, paint, or grease from garments?
Because it is a solvent for all greasy, oily matters.
What are the best agents for depriving putrid and decaying animal and vegetable substances of their offensive odors?
Chloride of lime is the most effectual agent; and chloride of zinc and sulphate of iron (green vitriol) are also exceedingly efficient. On a large scale, as in the sanatory cleansing of towns, pulverized charcoal, burnt clay, and quicklime are to be recommended.
What effect does the use of perfumes or the burning of pastiles have upon offensive odors?
They merely disguise the odor, but do not remove or destroy it.
By adopting what precautions may a person safely enter sick rooms, or visit, without risk, the most dangerous receptacles of filth?
By moistening a linen cloth with vinegar, and sprinkling over it finely-powdered chloride of lime.
Air breathed through this, applied to the mouth and nostrils, will enter the lungs charged with a minute quantity of chlorine, which will effectually destroy any noxious vapors or miasms that escape from diseased bodies, or from decaying animal and vegetable substances.
What three conditions are requisite to produce putrefaction in animal and vegetable substances?
It is necessary that they should be exposed to the combined influence of air, heat, and moisture.
Why is a substance preserved from decay by drying, or by the exclusion of air from it?
Because by so doing we remove the moisture and air essential to the process of decay.
Why does the smoking of fish or flesh contribute to their preservation?
Because the volatile matters of the smoke, such as creosote, pyroligneous acid, and the like, effect a species of chemical combination with the fiber of the meat, and with the substances contained in the natural juices of the flesh, which combinations are less liable to decay than the substances themselves.
What is albumen?
Albumen is an animal substance as well as vegetable. It exists most abundantly, and in its purest natural state, in the white of an egg, from whence it derives its name (album ovi), which is the Latin for the white of an egg.
The serum or fluid portion of the blood (which, after exposure to the air, is separated from the more solid part), the vitreous and crystalline humors of the eye, the brain, the spinal marrow, and nerves, all contain albumen.
What is the yolk of an egg?
This also consists of albumen, but contains in addition a yellow oil, which imparts to it its color.
Why is meat tough which has been boiled too long?
Because the albumen becomes hard, like the white of a hard-boiled egg.
The best way of boiling meat to make it tender is this: Put your joint in very brisk boiling water; after a few minutes add a little cold water. The boiling water will fix the albumen, which will prevent the water from soaking into the meat, keep all its juices in, and prevent the muscular fiber from contracting. The addition of cold water will secure the cooking of the inside of the meat, as well as of the surface.
Why is meat always tough if it be put into the boiler before the water boils?
Because the water is not hot enough to coagulate the albumen between the muscular fibers of the meat, which therefore runs into the water, and rises to the surface as scum.
Why is the flesh of old animals tough?
Because it contains very little albumen, and much muscular fiber.
What is a poison?
A poison is any agent capable of producing a dangerous effect upon anything endowed with life.
In cases of poisoning by substances taken into the stomach, what course should be pursued, in the absence of medical attendance?
The first step is to evacuate the stomach by means of powerful emetics, and when vomiting has taken place, warm water and the white of eggs may almost always be given with advantage.
Can poisons administered for criminal purposes be almost certainly detected?
They can; chemical science within the last few years has made such advances that the most minute quantities of all the best known poisons can be detected with certainty long after death.
There is no poison so liable and certain to be found as arsenic, and in almost every case of poisoning with mineral poisons, science is enabled to detect the substance, even when life has been extinct for years, and the body nearly decomposed.
What is arsenic?
Metallic arsenic is an exceedingly brittle metal, of a steel-gray color. It vaporizes, when heated, with a strong odor of garlic, a property not possessed by any other metal.
The substance used as poison, and sometimes known as ratsbane, is arsenious acid, a compound of arsenic and oxygen. Arsenious acid has the form and appearance of a fine white powder.
What is the best remedy in cases of poisoning with arsenic?
The hydrated peroxide of iron (iron rust) is considered the best remedy.
The following is the best method for preparing this substance: Take common copperas (sulphate of iron) four ounces; dissolve in warm water in a glass, or porcelain dish, and add a small quantity of sulphuric acid, and afterwards ammonia solution, so long as a dense red precipitate is formed. This precipitate carefully strained off, and thoroughly washed in a filter with water, is hydrated peroxide of iron. So long as kept moist, it may be preserved for a great length of time.
Is lead a poison?
Lead and nearly all its compounds are dangerous and secret poisons; when received into the system, it frequently remains dormant for years, and then suddenly manifests itself in various forms of disease.
What is the disease called “painter’s colic”?
A disease to which painters and others working in lead are liable, in consequence of receiving into their system, imperceptibly, portions of lead.
Is it dangerous to sleep in, or breathe the air of, a room newly painted with paints containing lead?
It is highly dangerous, since the air is filled with a vapor of the lead compound used as paint.
Why are some waters, when conveyed through lead pipe, poisonous?
Waters which are very pure and contain much oxygen dissolved in them; waters which contain nitric acid compounds, such as those flowing from the vicinity of barn-yards, manure heaps, and those which contain common salt or organic matter, as water flowing from swamps and fields; waters containing soluble carbonates—all dissolve lead from the pipes through which they may be made to pass. Constant use of such waters, in the process of time, will introduce sufficient lead into the system to produce disease, which is often attributed to other causes.
What is verdigris?
Verdigris is a compound of copper, oxygen, and acetic acid. This, and all the compounds of copper, are very poisonous. The most efficacious antidotes for poisoning with copper are white of eggs and milk.
What is calomel?
It is a compound of two parts of mercury united to one of chlorine, forming the sub-chloride of mercury. The preparation, commonly known in medicine as “blue pill,” is a preparation of calomel.
What is corrosive sublimate?
A compound of mercury and chlorine united in equal proportions, forming the perchloride of mercury.
Are both these compounds, calomel and corrosive sublimate, poisons?
They are; corrosive sublimate, especially, is a most deadly poison. In case of poisoning by it, the most effectual antidote is white of eggs.
What is the process of preserving wood from decay, commonly termed “kyanizing”?
It consists in saturating the fibers of the wood with a solution of corrosive sublimate.
Poisonous substances, and corrosive sublimate especially, have the property of protecting animal and vegetable substances from decay. The skins of stuffed birds and animals, and the plants of a herbarium, may be protected from insects and decay, by washing them with a solution of corrosive sublimate. It should not, however, be forgotten that these substances by such treatment become themselves poisonous.
Give a list of the chief antidotes for poisons.
(See Book of the Human Body.)
What are the common names of familiar chemical substances?
Common Names of Chemicals
| Common Names | Chemical Names and Formulæ |
|---|---|
| Alum | Sulphate of Aluminum and Potassium |
| Aqua Fortis | Nitric Acid, HNO3 |
| Aqua Regia | Nitro-Hydrochloric Acid |
| Calomel | Mercurous Chloride, Hg2Cl2 |
| Carbolic Acid | Phenol, C6H5OH |
| Caustic Potash | Potassium Hydrate, KOH |
| Caustic Soda | Sodium Hydrate, NaOH |
| Chalk | Calcium Carbonate, CaCO3 |
| Copperas | Sulphate of Iron |
| Corrosive Sublimate | Mercuric Chloride, HgCl2 |
| Cream of Tartar | Potassium Bitartrate |
| Epsom Salts | Magnesium Sulphate |
| Ether | Diethyl Oxide, (C2H5)2O |
| Fire Damp | Light Carburetted Hydrogen |
| Galena | Lead Sulphide, PbS |
| Glauber’s Salt | Sodium Sulphate |
| Glucose of Grape Sugar | Dextrose, C6H12O6 |
| Goulard Water | Basic Acetate of Lead |
| Iron Pyrites | Iron Di-Sulphide, FeS2 |
| Jewelers’ Putty | Oxide of Tin |
| Laughing Gas | Nitrous Oxide, N2O |
| Lime | Calcium Oxide, CaO |
| Lunar Caustic | Silver Nitrate, AgNO3 |
| Mosaic Gold | Bi-Sulphide of Tin |
| Muriatic Acid | Hydrochloric Acid, HCl |
| Olefiant Gas | Ethylene, C2H4 |
| Plaster of Paris | Calcium Sulphate |
| Quartz | Silicon Dioxide, SiO2 |
| Realgar | Arsenic Di-Sulphide, As2S2 |
| Red Lead | Oxide of Lead, Pb3O4 |
| Rochelle Salt | Sodium Potassium Tartrate |
| Salammoniac | Ammonium Chloride |
| Salt, Common | Sodium Chloride, NaCl |
| Salt of Tartar | Potassium Carbonate |
| Saltpeter | Potassium Nitrate, KNO3 |
| Salts of Lemon | Oxalic Acid |
| Slaked Lime | Calcium Hydrate |
| Soda | Sodium Carbonate |
| Spelter | Zinc |
| Spirits of Hartshorn | Amm. Hydroxide, NH4OH |
| Spirits of Salt | Hydrochloric Acid, HCl |
| Sugar of Lead | Lead Acetate |
| Tartar Emetic | Potass. Antimony Tartrate |
| Verdigris | Basic Copper Acetate |
| Vermilion | Sulphide of Mercury |
| Vinegar | Dilute Acetic Acid |
| Vitriol, Blue | Copper Sulphate |
| Vitriol, Green | Ferrous Sulphate |
| Vitriol, Oil of | Sulphuric Acid, H2SO4 |
| Vitriol, White | Zinc Sulphate |
| Volatile Alkali | Ammonia |
What is meant by radio-activity and radio-active substances?
Radio-activity is the phenomenon associated with substances which spontaneously emit rays of unique penetrating power through the escape of electrons and their striking against other substances. Chief of the radio-active substances are radium, polonium, actinium, thorium, etc.
What is the history of these substances?
Henri Becquerel in 1896 first observed this in the case of potassium uranyl sulphate, the rays from which he found affected a photographic plate through black paper, thin plates of metal, etc.; the property was further traced in other uranium salts and in uranium itself. These rays are known as Becquerel rays, and have the further power to render air a conductor of electricity, and thus to discharge any electrified substance placed near them.
A charged electroscope forms a test of radioactivity, and the rate at which the leaves fall measures the degree. Different uranium salts have different degrees of radio-activity; some varieties of pitchblende, as also chalcolite, show the property in excess of uranium contained.
Madame Curie, by using the activity test for every precipitate obtained from pitchblende, succeeded in discovering the elements polonium and radium in 1898. The next year Debierne discovered actinium, another radio-active element in the same substance. Meanwhile Schmidt and Madame Curie independently found that the same properties were associated with thorium, its compounds and the minerals containing it. In 1903 Ramsay and Soddy discovered that radium continuously produces helium, the lightest of the inactive gases discovered by Ramsay in 1896.
Twenty-eight elements are now classed in three divisions with the three parents, uranium, thorium, and actinium. Potassium and rubidium have been shown to be radio-active, but otherwise the alkaline metals do not enter the classes.
Describe radium and its special properties.
What It Is Like.—To the eye a tiny sample of radium—or, to speak more correctly, of one of the radium salts, for radium in a pure state (i.e. the metal) has not been obtained as yet—presents no very striking appearance. All one sees is a few tiny crystals, or perhaps a few specks of whitish-looking powder, glowing in the dark with a faint phosphorescent light similar to that sometimes emitted by a piece of decaying fish.
The Radiations are of three kinds, comparable with those of the vacuum tube: Alpha-rays are heavy particles, positively charged, similar to the canal rays; Beta-electrons, negative like cathode rays; Gamma-rays resemble Röntgen rays. They penetrate matter to different degrees, behave differently under the action of a magnetic field, but under ordinary circumstances travel in straight lines.
But rays from different elements vary in penetration, and also with the absorbing substance, varying roughly with the density.
The Alpha-rays have a velocity of from 1.56 × 109 centimeters per second (radium) to 2.25 × 109 centimeters per second (thorium); they are particles of helium carrying a double charge of electricity. Beta-rays have a greater range of velocity and approach that of light. Both [895] Alpha- and Beta-rays are absorbed by a thickness of one centimeter of lead, but Gamma-rays pass through an inch of lead; they carry no charge of electricity, yet ionize the air and discharge the electrometer.
All the rays on impinging on solid particles give rise to secondary rays, sometimes called Delta-rays, electrons moving with comparatively low velocity. The Alpha-rays possess ninety-five per cent of the energy evolved and produce brilliant fluorescence in zinc sulphide, diamond, etc., the other rays producing this best in willemite and the platino-cyanides; all become absorbed and transmuted into heat.
Radium every hour generates sufficient heat to raise its own weight of water from freezing to boiling point.
The Spinthariscope.—This is a simple piece of apparatus invented by Sir William Crookes, by means of which some of the effects of the Alpha-ray particles can be observed in a very striking manner. It consists of a little screen covered with powdered zinc sulphide. A small fragment of radium is placed directly in front of the middle of the screen and in close proximity to it. On observing this screen in the dark through a suitable lens, scintillating little points of light are seen to be continually flashing into view and dying away. Each tiny spark is thought to be produced by the impact of a single Alpha-ray particle. That these particles or emanations must be matter in a state of extreme attenuation is proved by an experiment of Professor Curie’s in which a box constructed of platinum was pierced with two holes so minute as to be capable of retaining a vacuum, and yet these radium emanations passed through quite freely.
What are the medical uses of radium?
Ulcerous growths, birth-marks, and scars are beneficially treated, but so far the selective action of radium on tissue has not been determined, nor its bactericidal effect. Its results in the treatment of cancer have not yet reached a definite stage, though it has been widely heralded as a specific for that dreadful malady.
The application of the rays is by various methods: inhalation of the emanation; external application or injection of the emanation condensed on glycerine, vaseline, oil, water, etc.; or the taking of quinine, arsenic, bismuth, etc., on which the emanation has been condensed. Injections of very dilute solutions of radium salts, or insoluble salts suspended in water, are made. But external applications of the rays are considered most important; copper plates or linen are coated with varnish containing the salts, or glass tubes contain them, and the radiations are directly applied, the surrounding parts being protected with lead foil.
GAS METER INDICATOR DIALS.