Household chemistry for the use of students in household arts

Front matter

Class __/ A J T j

Book JZ_1^

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Chapter I. Introductory

Courses of instruction in Household Economics group themselves principally about foods or other materials used in the household, most of which are of so-called organic origin. Hence some fundamental instruction in the nature of organic compounds is necessary, and preferably should precede a course in household chemistry, which is largely an applied chemistry of the carbon compounds. Often, however, a preliminary course in organic chemistry cannot be introduced into the curriculum. For that reason, an outline of a series of lessons in the chemistry of the carbon compounds is given here, designed to be presented as lectures and experiments running parallel with the work in household chemistry and often merging into it. In such a combined course, the outline as given will need to be adopted to the allowed time, perhaps to the exclusion of the aromatic compounds, and it may be necessary to perform many of the experiments as demonstrations. To give the study its proper emphasis and value, stress should be placed less upon individual than upon type compounds, and upon their inter-relation and properties, always with a view to enriching and making more effective the practical knowledge which the student has of substances met in everyday life.

It may be pointed out, in addition, that a recent course in general chemistry of the most modern type should be required as a prerequisite of household chemistry. In such a course the subject matter should be so selected that the material handled in household chemistry shall not be entirely unfamiliar. For example, more definite information would be useful with regard to the constitution and properties of the imported metallic elements, and a few of their simple compounds.

Outline of Course in Organic Chemistry.

I. Original and Prksent Meaning of Term "Or-

ganic.^"' Importance of organic chemistry — Some diflferences between organic and inorganic compounds — Organic chemistry the chemstry of carbon compounds — The carbon atom : its valency ; graphic expression of valency ; tendency to combine with hydrogen.

II. Chain Hydrocarbon.

The Methane, Ethylene, and Acetylene Series.

Development of Series — Nomenclature — Common formulae and differential — Properties — Occurrence of important members.

Application to Gaseous and Liquid Fuels.

Experiments : Preparation of Methane, Ethylene and Acetylene.

Reaction for the double bond.

III. Isomerism Applied to the Hydrocarbons. Nature and effect of isomerism.

IV. Saturation and Unsaturation.

Meaning of — General formation of substitution and addition products — Isomeric forms — Formation of iodoform and chloroform.

Experiment: Preparation of iodoform.

V. AlvCOHOLS,

Derivation from the hydrocarbon through substitution — relation to metallic hydroxides — Nomenclature — General physical and chemical properties and reactions — Source and uses of important alcohols — Isomeric forms : primary, secondary, and tertiary alcohols — Unsaturated alcohols — Glycols and polyhydric alcohols — Sulphur alcohols or mercaptans.

Applications to liquid fuels ; to carbohydrates ; to fats ; to fermentation; preservation of foods.

Experiments: Preparation of ethyl alcohol.

Detection of methyl alcohol.

VI. Aldehydes and Ketones.

Formation from alcohols — Comparative properties and reactions — Name, source, and uses of important examples.

Application to carbohydrates; preservatives; flavoring extracts.

Experiment: Preparation of formaldehyde, acetaldehyde and acetone.

Reduction by aldehydes, such as the Fehling's reaction.

VII. Fatty Acids.

Formation from aldehydes — Nomenclature — General properties and reactions — Occurrence and properties of important examples — Unsaturated acids : occurrence and characteristics.

Application to fats and oils.

Experiments: Preparation of acetic acid.

Separation of a fatty acid from a fat.

Illustration of drying and non-drymg property.

Hydrocarbon «•-'► Substitution »-* Alcohol »-^ Aldehyde *-*- Acid

IX. Este:rs.

Formation of type esters reviewed — Waxes — Glyceryl esters of fatty acids : general properties ; occurrence and properties of important fats and oils.

Application to fats and oils.

Experiments : Decomposition of a fat.

Preparation of ethyl acetate.

X. Ethers.

Formation — Analogy to metallic oxides — Nomenclature — Important example — Properties — Relation of ethers to alcohols ; of thio ethers to mercaptans.

Application: Ether extraction processes.

XL Oxidation Products of Gi.ycoi,s and Poi^yhydric Alcohols.

Hydroxyacids — Dicarboxylic acids — Special examples : Glycollic, lactic, sarcolactic, oxalic, succinic, malic, tartaric, citric, aconitic. — Sources and properties.

Application to milk; to muscle; to fruits and fruit juices.

XII. Nitrogen Compounds.

1. Alkyl Cyanides.

Analogy to halogen derivatives — Hydrolysis of cyanides — Other cyanogen compounds : properties and uses of — Prussian blue as bluing.

2. Amines.

Primary, secondary and tertiary amines — Quaternary ammonium bases — Unsaturated amines and related compounds — Important examples.

3. Amides.

Structure and properties — Amides of dicarboxylic acids — Important examples.

4. Amino Acids.

Formation — Nomenclature — Properties and reactions Important examples — Synthesis to peptids — Relation to proteins.

5. Proteins.

General composition, properties, etc.

6. Piirin Group.

XIII. Aromatic Compounds.

Benzene ring — Homolgues — Benzene, naphthalene and anthracene: source and importance — Benzene derivatives analogous to those of the straight chain series — Formation of substitution products ; phenols ; alcohols ; aldehydes ; acids; amino compounds; diazo compounds; leuco compounds — Properties and commercial importance of compounds — Dyes.

Experiments : Preparation and detection of benzaldehyde and of benzoic acid.

Detection of vanillin and saccharin and salicylic acid.

Preparation of aniline.

Diazotizing aniline.

Coupling diazos and phenols.

Formation of leuco compounds.

Reduction of indigo blue and subsequent oxidation.

Preparation of helianthin and eosin.

Chapter II. Atmosphere And Ventilation

Probably no subject so important to life as the air we breathe is so little understood, nor is there any other instance of so many evils arising from ignorance. A knowledge of the relation of pure air to health and efficiency should be a part of the education of people in general. In no other way will there be a solution of problems of ventilation in homes and public buildings, or of sanitary housing in large cities, and the stamping out of devastating diseases. A fundamental knowledge of the properties and functions of the atmosphere, and the principles of ventilation, is therefore all-important for the student of household chemistry.

Composition of the Air. — Pure air is not a compound of definite composition, but a mixture of gases. The two most important, oxygen and nitrogen, occur in the proportion of about 20 parts of the former to 79 of the latter. Other essential constituents are carbon dioxide, which in pure air averages in amount a little over 3 parts in 10,000, or 0.03 per cent, to 0.04 per cent., and aqueous vapor. Traces of argon, krypton, neon, ozone, hydrogen, ammonia, nitrogen acids, nitrites and nitrates, helium, and several other substances are normally found in varying amounts.

In addition to the above, there are always present in ordinary air many substances classed as impurities, the kind and amount varying with the locality. Dust from the soil and from factory operations is found as suspended matter, together with micro-organisms, pollen, plant seeds,, and soot. Offensive gases may contaminate the air of manufacturing centers, but they are usually more disagreeable than dangerous. The air of cities contains anywhere from lOO to 5,000 times the amount of dust and bacteria that is found in country air.

Properties and Uses of Constituents. — Oxygen. — Oxygen is the life-supporting element for all animals and plants. Diluted as it is with nitrogen, the oxygen of the air is in the condition and proportion best adapted to sustain most forms of life. In materially increased amount it is a poison to human beings; on the other hand, life cannot exist if the proportion falls to fourfifths of the normal, or 16 per cent, instead of about 20 per cent.

In animal organisms, a relatively small amount of oxygen is concerned in the process of respiration. Of 20.9 per cent, inhaled by human beings, 16 per cent, is returned in the exhaled air, together with about 4.4 per cent, of carbon dioxide. The oxygen used, however, in the respiratory exchange suffices to supply heat and energy to the body by means of oxidative processes in \.W protoplasm of tissue cells.

Plants require oxygen for respiratory and other processes as animals do. Part of the necessary amount is inhaled; part is obtained in the process of photosynthesis, through the action of chlorophyll and sunlight. A plant lacking in chlorophyll, such as a mush-

HOUS^HOI^D CHEMISTRY 9

room, absorbs oxygen directly from the air; green plants, in the presence of sunlight, build up carbohydrate material in their cells by synthesizing carbon dioxide and water, and in the operation release oxygen. The cells use as much of this as they require; the excess is returned to the air. It is estimated that an acre of woodland withdraws in one season about 4^ tons of carbon dioxide from the atmosphere, and returns 3^ tons of oxygen.* In darkness the chlorophyll becomes inactive; the plant then takes oxygen from the air. It is probable that the roots absorb oxygen from the soil and from ground water.

Ozone. — Ozone is a peculiar form of oxygen which exists as O3. It is produced from O2 by electrical discharge, by the action of moist air on phosphorus, or by several chemical reactions, such as the action of concentrated sulphuric acid on potassium permanganate. Its odor is noticed around static electrical machines and during thunderstorms. Ozone is a powerful oxidizing agent, but is found only in minute quantities in ordinary air. The salubrity of the air in evergreen forests is ascribed to ozone, formed as a product of the slow oxidation of turpentine and similar plant products.

Nitrogen. — Nitrogen is an inert gas; it does not burn nor support combustion, and its chief value to organisms is in the form of compounds. It is not utilized in human respiration except as a diluent of oxygen. In the plant world certain species of bacteria such as the * Harrington : Practical Hygiene, micro-organisms found in the root nodules of some legumes, carry nitrogen directly to the pea, bean or clover. How far other plants are able to utilize atmospheric nitrogen is a question. The main source of the organic nitrogen in their tissues is the nitrogen compounds in the soil due to micro-organisms and ammonia and nitrates washed down by the rain.

Carbon Dioxide. — Carbon dioxide is a heavy gas which will not support combustion or respiration. It is the result of oxidation processes, either in respiration, fermentation, the burning of tons of fuel, or chemical action in the soil. Harrington estimates that 5,000,000,000 tons are discharged annually into the atmosphere. The amount of carbon dioxide in the air may vary from two parts in 10,000, or 0.02 per cent, in the purest air to 30, 40 or even 100 parts in bad conditions of overcrowding. Only in greater amount, however, such as was found in the Black Hole of Calcutta, is it destructive to animal life. Undiluted, it causes instant suffocation by spasmodically closing the glottis.

On account of the solubility of carbon dioxide in water, considerable amounts are taken out of the atmosphere by rain and go to form carbonates in the soil or remain as carbon dioxide in the water.

Aqueous Vapor. — The term aqueous vapor is misleading and does not strictly represent the gaseous form in which the water in question exists in the atmosphere. The amount of aqueous vapor which a given volume of air is capable of holding without condensation depends house:hoi.d chemistry II

upon the temperature of the air. At o° C, a cubic meter of air is saturated if it contains 4.87 grams of moisture ; at 20° C. or 68° F. it can contain 17.157 grams, and at 32° C. or about 90° F. it may hold 30 grams. It follows that a precipitation of moisture results when the temperature of vapor-laden air changes from a higher to a lower point. The temperature at which moisture is deposited is called the dew point.

The rate of elimination of moisture from bodies depends largely on the amount of moisture already carried by the air. When air is saturated, it can take up no more; evaporation, therefore, cannot occur, and the moisture normally given off by the human body, for example, is deposited on the surface of the skin. This most disagreeable condition of stickiness is associated with days of great humidity in summer, with moist, raw days in winter, and with overheated crowded rooms.

Humidity is measured in terms relative to the saturation point of the atmosphere at any given temperature. A relative humidity of 50 means that the air contains only 50 per cent, of its moisture-carrying capacity at that temperature. The limits of comfort are generally given as between 40 and 75 ; a humidity of 75 to 100 is oppressive to man but beneficial to plants.

The relation of ptmospheric moisture to heat is most important. Water has a great capacity for heat and gives it up slowly. It acts therefore as an equalizer of the sun's heat and a moderator of temperature. In semiarid and desert regions, where the air is moisture-free, 2 and at high altitudes where the amount of vapor is relatively less, extreme heat during the day and a sudden fall of temperature at night are observed. It is estimated that the absorptive and radiative powder of aqueous vapor is 16,000 times that possessed by air.

Dtut. — The relation of dust to aqueous vapor is significant. Without this suspended matter in the air there would be little or no precipitation of moisture, but a constant state of saturation would be possible. The particles act as nuclei round which vapor condenses as fog or rain. In large manufacturing cities the prevalence of soot and dust in the air accounts for frequent fogs. Bacteria cling to dust particles and with them are washed out of the air by rain.

General Properties of the Air. — Density, — The density of the atmosphere varies, the principal factor in variation being altitude. At 3>4 miles elevation it is only one-half as dense as air at sea level and therefore exerts one-half the pressure. The normal pressure of the atmosphere at sea level upon each square inch of surface is about 15 pounds, but this pressure, which amounts to 30,000 pounds on the average body, is not appreciated, since it is exerted equally in all directions. Air pressure is commonly measured by the height of the column of mercury which it is capable of supporting, the recording instrument being called a barometer. A normal pressure at sea level, exerted on the mercury at the base of the barometer tube, is sufficient to raise in the tube a column

HOUSEHOI.D CHKMISTRY 1 3

of mercury weighing 14.7 pounds. This is called a pressure of i atmosphere.

When the mercury falls in the barometer, which usually happens before a storm, it is evident that atmospheric pressure has become less. This is because the air at such times probably contains more than a normal amount of water vapor, which is lighter than air, its density being 9, while air averages 14.5. The term heavy, sometimes used to describe the atmosphere in this connection, is contrary to fact. A further explanation of the barometric condition is found in the fact that as different portions of the earth's surface become unequally heated, the warmer areas impart corresponding heat to their atmosphere. This causes a rising and dilation of air over a given section, the heated column overflowing at the top upon the cooler surrounding atmosphere. Diminished pressure results in the rarefied column, with consequent expansion and a fall in temperature, until the moisture-precipitation point is reached, and the contained vapor of the air is condensed as cloud or rain. In changing from the vapor to the liquid form latent heat is released, which increases the rarefaction, and the upward movement and overflowing of the air column continue. Thus is created a condition of low pressure which the barometer indicates, while in the surrounding areas high barometric readings will be found. The rain area will naturally correspond with the area of low pressure.

Diffusion. — By a fortunate provision of nature, gases of different specific gravities do not lie in strata when mixed, but diffuse until the mass is of uniform composition throughout. If it were otherwise, a layer of carbon dioxide, which is a heavy gas, would blanket the earth, and offensive and poisonous gaseous emanations would make most localities uninhabitable. As it is, all such gases diffuse through the atmosphere as soon as produced. Stratification of the air is not, however, entirely controlled by diffusion. The local movements of air currents caused by unequal heating operate like a motor fan and are a most potent equalizing influence.

Heat Capacity. — Air has a considerable capacity for taking up heat, which is utilized in hot air heating.

Liquid Air. — Air can be liquefied by causing it to escape slowly from tremendous pressure, so that much heat is absorbed in expansion. The temperature of liquid air is nearly 400° below zero Fahrenheit. In this state it volatilizes rapidly at room temperature, the more volatile nitrogen being given off first. This leaves an available source of oxygen, which is utilized in filling oxygen tanks. Liquid air has a faint blue color.

EXPERIMENTS ON AIR.

1. Presence of Oxygen. — Four an inch of alkaline pyrogallol into a short broad test-tube, dose with a rubber stopper, invert and mark the position of the stopper and liquid on a gum label pasted on the outside of the tube, shake the tube well, invert and open under water, mark the level of the water in the tube when open, and explain the phenomenon.

2. Carbon Dioxide — Expose a few drops of lime-water or barium hydroxide on a slide to the air and notice that, by the end of the lesson, it is cloudy. What is the precipitate? Write the reaction.

3. Hydrogen Sulphide. — Moisten a filter-paper with a solution of acetate of lead and expose to the air until the end of the lesson. Notice the black coloration due to the formation of lead sulphide. This test works well in gas-lit rooms.

4. Aqueous Vapor — Saturate a strip of paper with cobalt chloride or iodide, thoroughly dry and expose to the air out and in doors; under moist conditions, it turns pink.

Weigh a small watch-glass containing about i gram of fused calcium chloride, wait about 2 hours and weigh again. Note the increase in weight largely due to water.

5. Dew Point Take the temperature of the room, immerse

the thermometer bulb in a glass of water, and add ice little by little until the first indication of moisture is seen on the outside of the glass. If humidity is low, add salt to hasten process. Note the thermometer reading; it is the dew point of the air in the room.

6. Determination of Relative Humidity — Use a sling or whirl psychrometer This instrument has two thermometers fastened to a frame which can be whirled in the hand. The bulb of one thermometer is covered with muslin which is made wet at the beginning of the test. As the instrument is whirled evaporation around this bulb reduces the recorded temperature until the dew point is about reached, that is, the temperature at which no further elimination of moisture takes place, but condensation occurs. When the wet bulb thermometer registers its lowest point the reading of both is taken and the dew point calculated. (See Glaisher's table. Harrington: Practical Hygiene.)

7. Relation of Dust to Rain — Fit a 2-liter flask with a rubber stopper having 2 perforations. Pass 2 pieces of glass tubing through these, long enough to extend nearly half way into the body of the flask. Attach pieces of rubber tubing fitted with pinch-cocks to the free ends of the glass tubing just above the stopper. Put in the flask sufficient water to a little more than fill the neck when the flask is closed and inverted. Keep the flask inverted and allow the confined air to become saturated with aqueous vapor. Now withdraw some of the air in the flask by suction through one of the rubber tubes. The decreased pressure causes a fall in temperature and a condensation of moisture as haze or fine rain throughout the air space in the flask. At this point introduce air through the rubber tubing to restore the original pressure and the mist disappears. Now wash the air in the flask with the contained water until its dust content is removed. Repeat the experiment and note that no rain is produced in the dust-free air.

8. Atmospheric Pressure — Pour 2 inches of water into a clean ordinary half gallon can, boil vigorously and close the opening with a close fitting cork. Remove the burner and when cool the can will collapse. The can should have a small opening and preferably be rectangular in shape.

Ventilation.

The scope of this book prevents a detailed discussion of ventilation and ventilatory systems. In fact it does not seem possible at present to make definite statements in regard to standards of temperature and composition of air in a well- ventilated rcKDm, since the whole subject of ventilation is undergoing revision. Experts disagree as to the comparative physiological effects of the constituents of vitiated air, and if perfect systems of ventilation have been devised, they are not in general use. However, until all buildings are equipped with such a system as a matter of course, a few facts and principles should be generally known and brought to bear on the ventilation of rooms under individual control.

Effect of Heat and Humidity. — It has been well established that the main factors causing discomfort in poorly ventilated rooms are excessive heat and humidity. With increase in temperature, due perhaps to overcrowding, the moisture in the air increases proportionately toward saturation point. Evaporation from the body now becomes relatively impossible. But at a temperature of 70° F. or over the body depends upon evaporation of perspiration to maintain its heat equilibrium. The danger now arises that the checking of evaporation may cause the cutaneous blood vessels to become so congested that the temperature of the skin is raised and heat transfer by conduction and radiation is increased. This occurs at the expense of the efficiency of the other organs, particularly the brain. Headache, dizziness, and even fever may result. Relief is at once felt in such cases if evaporation is aided by setting in motion the air in the room. If this cannot be done by bringing in free currents of outside air, electric fans answer the purpose.

On the other hand, too rapid evaporation of water from the skin and air passages will cause discomfort. This is felt in the dry air of steam-heated rooms. The skin becomes too dry, the cutaneous nerves are irritated, and the effect is felt by the central nervous system. This trouble may be obviated by the evaporation of water from a dish placed on the radiator.

The relation of heat and humidity to efficiency is

clearly pointed out in an article on Work and Weather*

by Dr. Ellsworth Huntington. The efficiency curves of

ing a period of 4 successive years, and those of 1,600 students at West Point and Annapolis, for periods of 2 and 6 years respectively. The declination in amount of work done is greatest at two periods of the year — through January and a part of February, when windows are kept closed and indoor conditions of temperature and humidity are below standard, and from the latter part of June to the end of August. In the summer of 191 1, part of which was the hottest in 100 years in the locality where the observations were made, the efficiency of the operatives dropped astonishingly; in 1913, a cool summer, there was very little lowering of the curve.

Carbon Dioxide. — Contrary to former belief, carbon dioxide in the largest quantities likely to occur in the air of a room has little to do with the feeling of discomfort. If the room is kept cool, the increase may be up to 20, 30, or even 40 times the normal amount^ without appreciable effect, and no serious physiological disturbance results until the carbon dioxide content is raised to about 3 per cent, with a corresponding lowering of the oxygen. This is approximately 75 times the amount present in pure air. At this point Dr. Angus Smith found feebleness of circulation, slowing of heart action, and quickened respiration, but could detect no inconvenience with 2 per cent. Pettenkofer and Voit experienced no discomfort after long exposure to air containing I per cent, of carbon dioxide.-

^ Rideal : Report on Hygienic Value of Gas and Electric Lighting, presented before Royal Sanitary Institute, London, 1907. ' Education : London, Feb. 1912.

HOUSKHOLD CHEMISTRY IQ

An adult will add 0.6 cubic foot of carbon dioxide to the air in i hour. Therefore in a room containing 3,000 cubic feet, the carbon dioxide will increase in that time 0.2 cubic foot per 1,000, or 0.2 part per 10,000, i.e., from an initial amount for pure air of 0.04 per cent., to 0.06 per cent., which is the limit of the standard of purity generally given. Theoretically the air of such a room with one occupant would require renewing each liour, but fortunately the average room, not being airtight, is constantly receiving some outside air through various openings.

"Crowd Poisoning." — Dr. Rideal states that the worst that can be said of even respiratory carbon dioxide is that it is often found in bad company. Emanations of a poisonous nature given off in breathing, cause the unpleasant odors noticeable to a person coming into an occupied room from the outside air. Disease germs are likely to be present, and to circulate more freely if dust is in the air. Moreover, sharp particles of dust may have an irritating or lacerating effect on eyes, nose, or lungs, making the tissues more susceptible to the entrance of bacilli. Tuberculosis is commonly spread in this way.

Experiments made under the direction of C. E. A. Winslow, chairman of the New York State Commission on Ventilation (1914), show the effects of heat, humidity, and stale air. It was found that when the temperature of the room was raised from 68° to 75°, the pulse and blood pressure were affected, and the amount of physical work accomplished fell 15 per cent. None of these bad effects were felt if the room was kept cool, although the air was allowed to become stagnant for 8 hours, so that the carbon dioxide content increased to about 20 times the amount in pure air. A marked effect of this stale air on the subjects was, however, loss of appetite, although the odors accumulating in the room were not noticed by them. This sub-conscious result was proved by serving standard meals and calculating the amount eaten after a period spent in fresh air and in stale air.

Methods of Ventilation. — Of the two methods of ventilation — natural and mechanical — the former is the one which must be depended upon in ordinary houses. Natural ventilation relies upon the movement of air currents caused by differences in temperature and gravity, and the force of wind — an uncertain agent. It takes into account the fact that air becomes lighter when heated, and rises. Heated 50° F. above the outside air, the air of a room will be increased one-tenth in bulk, since it expands Vsoo ^^ its volume for every degree Fahrenheit. Consequently, since good ventilation requires a constant supply of pure air and a corresponding removal of foul air, there should be an inlet and an outlet, the latter at the top of the room where the heated air can escape, the former nearer the bottom, where the colder air entering can have an opportunity of circulating through the room and pressing the warmer air upward. The problem of ventilation in winter often becomes a question of draughts. If the inlet is arranged so that the air may pass in a vertical direction over the heads of the occupants of the room, and at the same time be somewhat warmed, this trouble is remedied. If the opened window is the only form of inlet possible, a direct draught can be prevented by placing a frame in the opening covered with some open mesh material such as cheesecloth.

The inlets and outlets should be as far as possible from each other, so that air will not pass directly from one to the other without circulating. An outlet should properly have the motive power of heat or an exhaust, otherwise it may become an inlet for cold air. The wind acts uncertainly as an exhaust at times; a mechanical arrangement is more dependable. A fireplace is a desirable natural outlet, having the extra motive power of heat.

Heating by hot air is favorable to a good scheme of ventilation^ provided (i) that a steady supply of pure air from outside is brought in to be heated and circulated through the flues; (2) that an outlet for foul air be provided in the room.

Stoves, steam and hot water heating systems offer little aid to ventilation. On the contrary, stoves withdraw the purer air near the floor for purposes of combustion. Careful attention to ventilation is necessary with these methods of heating.

Too often people live in tight shut rooms in winter because they cannot afford loss of heat by ventilating openings. The injury to health is apparent in even a few weeks, in lessened vitality, susceptibility to colds, and actual disease. In such cases occasional throwing open of windows with rapid exercise at the time answers the purpose with less loss of heat. If one can become accustomed to free circulation without draughts, the body tone is raised so that less heat is required and the chances of injury on exposure are lessened.