295 
melting of sulphur by heating flowers of sulphur in small flask. 
Heat sulphur on a piece of tin plate till it catches fire, show the 
colour of the flame and observe the smell of burning sulphur. 
Prepare sulphur dioxide by heating copper turnings in sulphuric 
acid, and show that it extinguishes flame, is very soluble in water, 
and that the water dissolving it becomes very acid, turning blue 
litmus red. Bubble air through a strong solution of sulphur 
dioxide, and then over platinised asbestos ; demonstrate that when 
the platinised asbestos is hot dense white fumes are formed of the 
sulphur trioxide. Pour some sulphuric acid into 20 or 30 times 
its volume of water and prove its acid taste, its action on litmus, 
and its power of causing effervescence if dropped on sodium car- 
bonate. Show that sulphuric acid is a colourless liquid, that bulk 
for bulk it is much heavier, more than 19 times, than water. 
Show bya thermometer or by immersing a test tube with spirit in 
it that a large amount of heat is evolved when this acid is poured 
into water. Pour sone on sugar or shake it up with oil to show 
its action on organic bodies. 
CHLORINE.—The gas obtained by the action of hydrochloric 
acid on the black oxide of manganese. So called on account of 
its colour. Its characteristic smell. Is 24 times heavier than 
air and 354 times heavier than hydrogen. Soluble in water. 
Many substances take fire in chlorine gas, e.g., phosphorus, and 
form chlorides. Ignition of oil of turpentine in chlorine with 
separation of carbon and formation of hydrochloric acid. Bleach- 
ing power of chlorine. Bleaching-powder. 
Lxperiments.—Samples of common salt, rock-salt. Prepare 
chlorine from (1) mixture of common salt, black oxide of man- 
ganese and sulphuric acid ; (2) from mixture of black oxide of 
manganese and hydrochloric acid. Collect gas by downward 
displacement. Draw attention to its colour, and show that 
phosphorus spontaneously inflames in the gas to form chemical 
compound of phosphorus and chlorine. Show that oil of tur- 
pentine ignites spontaneously in chlorine. Show that sodium when 
strongly heated burns in chlorine and forms common salt. Show 
bleaching action of chlorine by dipping moistened Turkey red 
rag in bottle filled with gas. Show similar action with solution 
of bleaching: powder and acid. Show that chlorine is soluble in 
water and that the solution has characteristic smell and colour of 
the gas. 
Acips.—Are bodies which have sour taste, turn blue litmus 
red, and liberate carbon dioxide when added to solution of sodium 
carbonate. Sulphuric acid has these properties. Its specific 
gravity. Colourless when pure. Evolves heat on being mixed 
with water. There are two other common bodies which have 
strong acid properties like sulphuric acid, these are nitric acid 
and hydrochloric or muriatic acid; these are made of different 
constituents from sulphuric acid. All act on litmus, &c. in same 
way ; allcan be neutralised by potash forming potassium sulphate, 
or nitrate, or chloride. The compound formed by the union of 
an acid and alkali is called a salt. All three acids are colourless 
liquids, but, beside the properties possessed by all acids, each acid 
has properties which belong to it alone. Nitric acid attacks most 
metals. 
are formed. Hydrochloric acid does not dissolve copper, is not so 
heavy as sulphuric acid ; when mixed with manganese dioxide 
gives off a yellow irrespirable gas known as chlorine. 
Experiments.—Samples of both nitric and hydrochloric acid. 
Show that they have all the properties belonging to acids and that | 
by neutralising them common salt and nitre can be made. Show 
the action of nitric acid on copper, tin foil, &c. Show that it has 
no action on platinum or on gold. Copper placed in hydrochloric 
acid not attacked, but if mixed with manganese dioxide and 
warmed chlorine is given off. 
ALKALIES.—Are another class of bodies which turn red litmus 
blue ; have soapy taste and absorb carbon dioxide. 
be added gradually to sulphuric acid the properties of both bodies 
gradually disappear, and at last a liquid is obtained that has no 
action on litmus. The combination of acid and alkali and the 
body formation of sulphate of potash or potassium sulphate ; sul- 
phate of soda or sulphate of ammonia can be formed in asimilar 
manner. 
Lxperiments.—Show that solutions of potash, soda, and 
ammonia turn reddened litmus blue, and that when a tube con- 
taining carbon dioxide is inverted in any of these solutions the 
gas is absorbed. The taste of these bodies is soapy not sour. 
Add gradually to dilute sulphuric acid one of these bodies, and 
see that the acid character of the dilute sulphuric acid disappears. 
Neutralise exactly sulphuric acid with potash, then evaporate and 
crystallise out the salt formed. 
Poured on copper the metal is dissolved and red fumes | 
If potash | 
NATURE 
[Fuly 29, 1886 
AMMONIA.—A gas with a very pungent smell, Solution in 
water. One volume of water dissolves 800 volumes of ammonia. 
This liquid has the pungent smell of the gas, and it can neutralise 
the strongest acids. Formation of ammonium zhloride or sal 
ammoniac by ammonia with hydrochloric aci¢. Ammonium 
chloride a white solid, soluble in water, with no smell of ammonia. 
Ammonium chloride a volatile body. The effect of boiling a solu- 
tion of ammonium chloride with lime or potash. Ammonia is com- 
posed of 82°3 parts of nitrogen and 17°7 parts cf hydrogen. The 
pungent odour of smelling salts is due to ammonia. Animal 
matters, such as horn, dried flesh, glue, cheese, isinglass, heated 
so as to decompose these bodies, yield ammonia. The formation 
of ammonia in large quantities by heating coal to make coal gas. 
Production of ammonia when animal matters containing nitrogen 
putrify. 
Experiments.—Prepare ammonia by treating ammonium chlo- 
ride with an equal weight of slaked lime and enough water to 
make the whole into a thick mud ; and demonstrate its smell, its 
action on red litmus, and its great solubility in water. The gas 
passed into water, the increase of volume of the liquid. Its pro- 
perties and their identity with those of the gas. Volatility of 
ammonia shown by the liquid leaving no residue on evaporation. 
Show that ammonium chloride is formed by neutralising a solu- 
tion of ammonia with hydrochloric acid, and is obtained as a solid 
on evaporation, and that on further heating it is volatilised, Heat 
coal in a coarse powder in a glass tube, and show that the liquid 
obtained is very alkaline. Show the formation of ammonia by 
the addition of potash and lime to a solution of ammonium chloride. 
LIME AND CLAy.—Limestone, marble, oyster-shells, chalk, 
all contain a metal known as calcium. The oxide of this metal 
known as lime. Lime and carbon dioxide are together present 
in limestone, marble, shells, and chalk. When these are strongly 
heated, especially in a current of air, the carbon dioxide is evolved 
and the lime is left. Action of water on lime. Its use in making 
mortar. Lime slightly soluble in water. On blowing carbon 
dioxide into a clear solution of lime (lime-water), liquid becomes 
turbid, owing to combination of carbon dioxide and lime to form 
chalk. Same effect on breathing through lime-water. Other 
important salts of lime are gypsum or plaster of Paris (sulphate 
of lime) and phosphate of lime, which exists largely in bone. 
Clay is a combination of a body called silica, which is the chief 
constituent of sand and flint, with the oxide of a metal known as 
aluminium, so called because it exists also in alum. Glass is a 
compound of silica with lime and an alkali, potash or soda. 
Varieties of clay ; their use in manufacture of bricks and pots. 
The metal of clay (aluminium), a white body with a brilliant 
lustre, 25 times heavier than water ; may be rolled out into thin 
sheets and drawn into fine wire. Not oxidised in the air, 
Experiments.—Samples of limestone, marble, oyster shells. 
Show that these substances effervesce with dilute hydrochloric 
acid, and that a gas carbon dioxide is evolved. Heat a piece of 
limestone or marble to redness in a fire, and show that after 
heating it no longer gives off carbon dioxide on treatment with 
an acid. Describe process of lime-burning. Properties of lime 
as distinguished from limestone. Show that a piece of moistened 
red litmus paper pressed against limestone is not affected, but 
that when pressed against lime it is turned blue. Show slaking 
of lime ; draw attention to heat evolved. No such result on 
treating limestone with water. Show that lime is soluble in 
water, whereas limestone is not. Add carbon dioxide to the 
solution of lime, and show that white powder is formed which on 
treatment with acid evolves carbon dioxide again. Explain that 
white powder thus formed is identical in chemical composition 
with limestone, and hence that limestone isa compound of carbon 
dioxide and lime. Explain use of lime in making mortar. 
Various samples of clay are used in manufacture of bricks and 
pots. Show plasticity of clay and exhibit one or two specimens 
of ware before being baked. Show that a vessel of kneaded or 
“*puddled” clay will hold water. Explain chemical nature of 
clay, and show specimens of silica and alumina. Show alum and 
demonstrate that alumina is contained in it by heating ammonia 
alum. Show specimen of aluminium and explain that this metal 
is contained in alumina and therefore in clay. 
- METALS, INTRODUCTORY.—About 70 different elementary 
subjects known. Almost all the common metals are elements. 
For instance, iron, lead, copper, zinc, mercury, silver, gold, tin, 
are elements. All combine with oxygen to form oxides, with 
chlorine to form chlorides, and with sulphur to form sulphides. 
E-xperiment.—Specimens of metallic and non-metallic elements 
and of oxides and sulphides. 
