ba 
¥uly 29, 1886] 
NATURE 
295 
from the solution by evaporation. Saturate water with nitre, 
and show that the solubility is increased by increase of tempera- 
ture. Demonstrate the formation of crystals. Illustrate the 
removal of substances in suspension, and the non-removal of 
substances in solution by filtration. Show by evaporation the 
solid matter dissolved in a sample of pump, or river, or spring 
water, and explain the method for its quantitative determina- 
tion. Show the like solvent action with other liquids, as calcium 
chloride, in alcohol and sulphur in carbon disulphide. Compare 
the result of admixture of spirit or oil of vitriol with water with 
that of oil or mercury with water. Heat ordinary water and 
collect the expelled air. 
Arr.—Surrounds the globe. Wind is air in motion. Breathing. 
Air occupies space. The bulk of any quantity of air is much 
changed by temperature and by pressure. Air has weight. The 
necessity of air for animals and plants. Bodies when burning 
require air. Air a mixture of two gases. Oxygen and nitrogen. 
The proportion of nitrogen to oxygen. Oxygen the active body 
in air. Bodies burn in it alone and more brilliantly than in air, 
The combination of oxygen with iron and with other bodies. 
Increase of weight of bodies which unite with oxygen, Nitrogen 
does not combine directly with bodies. The nearly constant 
composition of pure air. Presence of other gases in small 
amount in air. Water in the airasagas, The drying up of 
water. 
Experiments.—That air occupies space may be shown by 
plunging a bell jar into a vessel of water. Fita flask containing 
water with an india-rubber plug and delivery tube, heat the 
water, and collect the expelled air over water. Close the short 
limb of a syphon tube containing air, and compress the air in 
the long limb by pouringin mercury. Weigh a flask, fitted with 
a stop-cock, full of air, and then exhaust by an air-pump, and 
weigh again. Show that a lighted candle is soon extinguished 
when burnt under a bell jar, but that it continues to burn if fresh 
air be from time to time supplied. Burn phosphorus in a tall 
bell jar over water, and show the diminution of bulk of air. 
Ignite phosphoius, place it in the remaining gas. Burn some 
phosphorus under a dry bell jar to show the compound of phos- 
phorus and oxygen which is formed. Place phosphorus in a 
graduated tube over water to show that at ordinary temperatures 
it combines with the oxygen of the air and removes it, so that 
by measuring the volume of gas left, the amount of oxygen con- 
tained in air can be roughly determined (to introduce the phos- 
phorus, fuse it in a test-tube under water, and introduce the end 
of a long wire into it, then let it cool). Burn charcoal and 
sulphur in oxygen, and call attention to their disappearance. 
Demonstrate by lime water and by litmus paper that a new body 
is in each case formed. Burn iron powder (ferrum vidactum) 
on a scale pan of a balance, to show that an increase of weight 
occurs. A glass or metal vessel filled with ice or cold water can 
be used to show the condensation of mixture upon it. Place 
calcium chloride on the pan of a balance to show the gradual 
increase of weight which occurs. 
WatTER.—Its three states. Expansion of water by heat. 
Equal volumes at different temperatures have not the same 
weight. Formation of currents in water by heating. Boiling 
point. Increase of volume on conversion of water into steam. 
Distillation. Pure water. Hydrogen and its properties. The 
burning of hydrogen in air, and the weight of the product com- 
pared with the weight of the hydrogen ; the difference due to 
oxygen of the air with which hydrogen has combined. Hence 
oxygen and hydrogen are the constituents of water. Combina- 
tion of oxygen and hydrogen with explosion to form water. If 
by measure there be twice as much hydrogen as oxygen, or by 
weight eight times as much oxygen as hydrogen, then no gas 
remains—all becomes water. All water composed of these two 
bodies in this proportion. These two bodies can then be sepa- 
rated from water and can be made to make, unite, and form 
water. In all cases of chemical combination bodies are united 
in constant proportion. 
Experiments.—Illustrate the characteristic properties of ice, 
water, and steam. Show that equal volumes of hot and cold 
water do not counterbalance one another. Fill a flask to the 
bottom of the neck with cold water, and then heat to show ex- 
pansion of the water. Show current by heating a large flask of 
water. To illustrate distillation, distil water containing copper 
sulphate. Show Liebig’s or other forms of condensers. Show 
the mode of determining the boiling point of a liquid. Show 
that the temperature remains constant, and that on dissolving 
substances in water the boiling point is raised. To show the 
presence of hydrogen in water, pass steam through a red-hot 
iron tube filled with coarse iron turnings or nails. Water formed 
of two components, both gaseous. Note the change in the 
iron both in appearance and weight. This increase of weight 
and the weight of gas which comes off equals weight of steam 
which has disappeared. Hence two substances in water, one 
the combustible gas that comes through the tube, the other the 
body which remains with the iron. Collect the hydrogen over cold 
water in proof that it is not steam, also show that it burns. 
After the tube is cooled show the iron from inside of the tube 
and explode the oxygen and hydrogen. Plunge a burning taper 
into jar of hydro en held mouth downwards, to show burning of 
the gas and extinction of the taper. Show by a balloon, or 
soap bubbles, or inverted beaker glass suspended froma balance, 
that hydrogen is lighter than air. Condense the water formed 
by the burning of a jet of hydrogen. 
Carbon.—Charcoal, graphite, or blacklead and diamond. 
When wood, sugar, meat, bread are heated carbon remains. 
Charcoal not changed in the air at ordinary temperatures. 
Combination of carbon with the oxygen of the air at a red heat. 
Carbon dioxide a compound of carbon and oxygen. Chemical 
combination of carbon and oxygen is attended by the evolution 
of adefinite amount of heat expressed by amount of water it will 
heat. Combustion. The properties of carbon dioxide. Water 
dissolves carbon dioxide at ordinary temperatures. Action of 
carbon dioxide on lime-water; no animal can live in this gas. 
100 parts of carbon dioxide are composed of 27'27 parts of 
carbon, and 72°73 parts of oxygen. Carbon dioxide obtained 
from marble, limestone, oyster-shells, chalk, &c. Charcoal fire. 
Coal composed of carbon, hydrogen, and a little oxygen, &e. ; 
its burning is the carbon and the hydrogen combining with 
oxygen. Whenever oil, tallow, coal gas are burnt this carbon 
dioxide and oxide of hydrogen (water) are formed. Respiraticn 
produces similar changes. In expired air the same products 
arise as from the burning of the food, and there is the same evo- 
lution of heat. Carbon a constituent of all animal and vegetable 
bodies. 
Experiments.—Specimens of charcoal. Make charcoal by 
heating wood in covered crucible. The black lead of a pencil as 
a specimen of graphite. Sugar heated on piece of tin plate. 
Show that acids and alkalies do not change charcoal, but that 
when heated it soon burns away, and only ash is left. Take a 
small piece of charcoal in a glass tube, pass air over it into lime 
water, and show no change takes place until the charcoal is 
made red hot ; as the charcoal disappears the lime water becomes 
milky. Show by means of the balance, or by soap bubbles, or 
by passing it from one vessel to another, that carbon dioxide is 
heavier than air, that it acts on lime water, that a burning candle 
is extinguished in it. Its solubility in water shown by agitating 
a tube of the gas over water. Prepare the gas from marble by 
the action on it of dilute acid. Collect all the gas given off from 
a small piece of marble weighing 5 or 10 grains. Show by 
collecting in inverted beaker the products of combustion of a 
candle, of a lamp, and of a gas flame, and adding lime water, 
that carbon dioxide is given off. Show also by means of lime 
water that respired air contains this gas. 
SuLPHUR.—Known also as brimstone. Where found. Its 
properties. Is also found chemically combined with many metals, 
so not recognisable by the eye. Sulphur heated in the air melts ; 
more strongly heated it burns, then the sulphur disappears ; the 
strong smell produced belongs to a new body formed by the burn- 
ing, a compound of sulphur and oxygen. Gaseous properties of 
the new body, its effect on blue litmus paper, which oxygen and 
sulphur have not. Its composition is 50°00 parts of sulphur and 
50°00 parts of oxygen, and it is called sulphur dioxide. Water 
dissolves nearly fifty times its volume of this gas, and then turns 
blue litmus strongly red and has an acid taste. The combination 
of the gas and water to form sulphurous acid. Another com- 
pound of sulphur and oxygen can be made, in which the same 
weight of sulphur is combined with more oxygen. One hundred 
parts contain 4o of sulphur and 60 of oxygen, and it is called 
sulphur trioxide. Sulphur trioxide has properties differing from 
the dioxide. If the dioxide and oxygen be mixed they do not 
combine, but if they are passed over hot platinum dense white 
fumes are formed, which are the trioxide. Combination of the 
trioxide with water to form sulphuric acid (oil of vitriol). i 
Experiments.—Show roll and flowers of sulphur and specimen 
of native sulphur, also iron pyrites and other native sulphides. 
Powder iron pyrites and heat it in a tube held horizontally over a 
lamp to show the sulphur obtained from the pyrites. Show the 
