Part 228

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.