Fuly 29, 1886 | 
NATURE 
297 
LEAD.—Its colour ; a fresh surface bright, but soon tarnishes 
in the air. Is heavy. Lead is 114 times heavier than water. 
Can be beaten or rolled into thin sheet or drawn into wire. 
Melts at temperature 633° F. Can becast in amould. Its com- 
bination when liquid with oxygen. Formation of lead oxide. 
The oxide has entirely different properties from lead. Removal 
of the oxygen when heated with carbon and the formation of 
metallic lead. Formation of red lead by heating the oxide. 
Solution of lead by nitric acid and the formation of lead nitrate. 
Solution of lead oxide by nitric acid and the formation of lead 
nitrate. Similarly to potassium nitrate this is to be termed ‘‘a 
salt.” Its solution in water. Other salts of lead, chloride, 
sulphate. Formation of sulphate and chloride of lead, their 
insolubility in water. Galena, or lead sulphide, one of the ores 
from which lead is obtained. 
Experiments.—Piece of lead to scrape and show it is then 
bright and has ‘‘ metallic” appearance. Show by balance that 
compared with water it is bulk for bulk much heavier. Show 
the metal beaten out into thin sheet, also as wire. Melt lead in 
an iron spoon, and cast in a mould. Show formation of oxide 
by blowing air onto the melted metal. Contrast the properties 
of the oxide with those of the metal. Convert the oxide again 
into metal by strongly heating an intimate mixture of it and 
charcoal powder. Heat the oxide to show its further oxidation 
and the formation of red lead. Show the action of nitric acid 
on lead, also on lead oxide, and. the formation of lead nitrate. 
Show this is “salt,” and prove that it is soluble in water. De- 
monstrate that the first is very slightly soluble, and the last 
almost insoluble in water. Show the formation of chloride and 
sulphate of lead by the addition of the respective acids to a 
solution of lead nitrate. Collect on filter the salts so formed, 
wash and dry them. Show specimen of Galena (lead sulphide). 
Tron.—Not used in a pure condition, always obtained united 
with carbon. Three kinds of iron; wrought iron, cast iron, and 
steel. Wrought iron the purest and used if the body is to be 
formed by hammering. Cast iron contains most carbon. Steel 
used for cutting instruments ; can be made into a magnet; can 
be ‘‘annealed.” Solubility of all three forms of iron in sul- 
phuric, nitric, and in hydrochloric acids, and the formation of 
iron sulphate, nitrate, and chloride. Their solubility in water. 
Melting point of iron is at much higher temperature than that of 
lead. Comparison of the weight of iron with that of water. 
Its colour. The ready action of air on it. Formation of rust. 
Oxidation by heating. The action of steam on iron when red 
hot. Oxide of iron heated with hydrogen or with carbon parts 
with its oxygen, and iron is left. Oxide of iron found in the 
earth. Hematite. A carbonate of iron mixed with clay used 
as a source of iron. Heating the ore the iron is converted into 
oxide. Removal of the oxygen by heating it to a very high 
temperature with carbon. Formation of slag from clay and lime. 
Experiments.—Specimens of the different kinds of iron, 
wrought iron, cast iron, and steel. Dissolve cast iron in hydro- 
chloric acid diluted with equal volume of water, show carbon 
which remains, filter and evaporate the liquid to show the chloride 
of iron formed. Heat iron wire by the blowpipe to show the 
high temperature required to fuse it. Iron acted on by air and 
moisture to show its rusting. Heat iron oxide in a tube and pass 
hydrogen over it to show formation of water and metallic iron. 
Show specimens of iron ores, clay iron stone. Hematite 
magnetic iron ore, and slag. 
Correr.—Its colour. Does not rust in air at ordinary 
temperatures. Thin wire melts in flame of Bunsen burner. 
When heated in air becomes black, owing to formation of an 
oxide. Oxide heated in hydrogen gas yields up its oxygen, water 
is formed, and the red-coloured copper is obtained. Action of 
acids on copper. With dilute nitric acid evolves a colourless gas, 
which turns red in contact with the air, and the metal dissolves, 
forming a green solution of copper nitrate. Heated with sul- 
phuric acid copper yields sulphur dioxide, the same gas which is 
formed when sulphur burns in air or in oxygen. Substance 
formed when copper dissolved in sulphuric acid is when crystal- 
lised from water of a fine blue colour, known as copper sulphate 
or blue vitriol. Action of vegetable acids on copper. Verdigris. 
Use of copper in alloys. A penny composed of 95 parts of 
copper, 4 parts of tin, and 1 part of zinc. Bell metal and gun 
metal contain copper and tin. 
Experiments.—Show specimens of copper in bar, sheet, and 
wire. Point out characteristic colour of metal. Heat piece of 
sheet copper over flame of Bunsen burner. Show formation of 
black film. Explain its origin. Take black oxide of copper 
and heat in hydrogen gas. Show that metal is again formed and 
that water is produced. Show action of nitric and sulphuric 
acids upon copper. Exhibit specimen of copper sulphate (blue 
vitriol). Show that on placing a knife blade in a solution of 
copper sulphate metallic copper is formed on the steel. Show 
sample of verdigris and explain how formed. Show various 
alloys of copper, bell-metal; brass, gun-metal, &c., a penny- 
piece. 
Mercury.—A liquid metal, but if it be cooled to — 40° 
Fahrenheit it is solid. Its metallic appearance. Its weight ; 
heaviest liquid known ; 13°6 times heavier than water. Use in 
the barometer and thermometer. Does not rust or tarnish in the 
air at ordinary temperatures, oxidation if heated to about 600° F. 
in the air, and the formation of red mercuric oxide, Is readily 
attacked and dissolved by nitric acid. It dissolves many metals, 
-.g., tin, lead, &c. ; amalgams. Mercury in combination with 
sulphur, as cinnabar. Mercury can be obtained from any salt of 
mercury by heat, volatilization of mercury, and the condensation 
of the vapour. 
Experiments.—Specimen of mercury. Show that to balance 
a given volume of mercury 134 volumes of water are necessary. 
Boil a little mercury in a tube to show it vaporizes. Treat 
mercury with nitric acid and show its solution. Show that tin 
foil is dissolved by mercury, which becomes less fluid. Heat 
mercuric oxide in a tube and collect both the oxygen and the 
mercury. Heat mercuric chloride in tube sealed at one end with 
dry sodium carbonate and show the metallic mercury condensed 
on the side of the tube. 
Soptum.—Common salt contains a metal combined with 
chlorine known as sodium. 100 parts of common salt contain 
39°3 parts of Sodium and 60°7 parts of Chlorine. Carbonate of 
soda (washing soda) contains sodium. Sodium obtained on 
strongly heating carbonate of soda with charcoal. Sodium one 
of the lightest solids known. Swims on the surface of water 
and decomposes that liquid with evolution of hydrogen and 
formation of the alkali soda. Other properties of the metal 
sodium : its low fusibility and softness. Its tarnishing in air. 
Preservation of sodium from action of air by being kept in same 
liquid lighter than water and free from oxygen. 
Experiments.—Samples of common salt and rock salt ; also 
washing soda and bicarbonate of soda. Recall experiment 
showing that chlorine is constituent of common salt. Show that 
washing soda and sodium bicarbonate evolve carbon dioxide on 
treatment with an acid. Common salt a compound of chlorine 
with a metal called sodium ; bicarbonate of soda and washing 
soda compounds of carbon dioxide and sodium. Sodium can be 
made by strongly heating sodiu n carbonate with charcoal. Ex- 
hibit specimen of portions sodium. Show that it can be cut with 
a knife, and that the so cut can be pressed together again. Ex- 
hibit metallic lustre of sodium ; show that it quickly tarnishes in 
the air. Show that sodium is lighter than water and decomposes 
that liquid with evolution of gas (hydrogen). Collect hydrogen 
from water by thrusting small piece of sodium beneath test-tube 
filled with water and standing in basin of water. 
Carbon CompouNpDs.—Large numbers of substances are met 
with in plants and animals which are not found in the earth. 
Most of these bodies contain carbon. The other elements united 
with the carbon are hydrogen, oxygen, nitrogen ; some bodies 
are composed of all these elements ; others of only two of them. 
Many of these bodies when heated leave black residue of carbon ; 
when this is more strongly heated it burns away. The great 
number of these carbon compounds, and the great difference in 
their properties. Sone are acids, ¢g., vinegar (acetic acid), 
and tartaric acid, Some are salts, eg, fats, tallow, butter. 
Some are neutral bodies, ¢.g., sugar, starch, spirit. 
Experiment.—Show that on heating any ordinary vegetable or 
animal substance carbon is left behind. 
Acetic Acip.—One form of dilute acetic acid is known as 
vinegar. Formation of acetic acid when beer or wine exposed 
to the air becomes sour. The spirit present combines with 
oxygen of the air and forms acetic acid. The presence of a kind 
of fungus called mycoderma aceti necessary to cause this oxida- 
tion. Large amount of vinegar is made from poor kinds of wine 
and beer. Action of vinegar on blue litmus, and on sodium 
carbonate. Vinegar is also made by heating wood in a retort ; 
a great many bodies distil over, among them acetic acid, The 
pure acid has very pungent smell, and has all the properties 
which are characteristic of the acids. Boils at 246° F. Dis- 
solves in water. It is composed of carbon, hydrogen, and oxygen 
in the proportion of 40’0 parts of ciwrbon, 6°7 parts of hydrogen, 
