Part 2 (1/2)

Lead Pb 206.II, IV ... ... ... ”

Lithium Li 7.I ... ...... ”

Magnesium Mg 24.II ... ...... ”

Manganese Mn 55.II, IV, VI ... ... ... ”

Mercury Hg 200.I, II 100. Liquid Nickel Ni 59.II, IV ... ... ... Solid Nitrogen N 14.(I),III,V 14. Gas Oxygen O 16.II 16. ”

Phosphorus P 31.(I),III, V 62. Solid Platinum Pt 197.(II), IV ... ... ... ”

Pota.s.sium K 39.I ... ...... ”

Silicon Si 28.IV ... ...... ”

Silver Ag 108.I ... ...... ”

Sodium Na 23.I ... ... ... ”

Strontium Sr 87.II ... ... ... ”

Sulphur S 32. II,IV,(VI) 32(96) ”

Tin Sn 118. II, IV ... ... ... ”

Zinc Zn65. II 32.5 ”

If more than one atom of an element enters into the composition of a binary, a prefix is often used to denote the number. SO2 is called sulphur dioxide, to distinguish it from SO3, sulphur trioxide. Name these: CO2, SiO2, MnO2. The prefixes are: mono or proto, one; di or bi, two; tri or ter, three; tetra, four; pente, five; hex, six; etc. Dia.r.s.enic pentoxide is written, As2O5.

Symbolize these: carbon protoxide, diphosphorus pentoxide, diphosphorus trioxide, iron disulphide, iron protosulphide. Often only the prefix of the last name is used.

16. An Oxide is a Compound of Oxygen and Some Other Element, as HgO. What is a chloride? Define sulphide, phosphide, a.r.s.enide, carbide, bromide, iodide, fluoride.

In Experiment 6, where S and Fe united, the symbol of the product was FeS. Name it. How many parts by weight of each element? What is its molecular weight? To produce FeS a chemical union took place between each atom of the Fe and of the S. We may express this reaction, i.e. chemical action, by an equation:--

Iron + Sulphur = Iron Sulphide Or, using symbols Fe + S = FeS Using atomic weights, 56 32 = 88.

These equations are explained by saying that 56 parts by weight of iron unite chemically with 32 parts by weight of sulphur to produce 88 parts by weight of iron sulphide. This, then, indicates the proportion of each element which combines, and which should be taken for the experiment. If 56 g. of Fe be used, 32 g. of S should be taken. If we use more than 56 parts of Fe with 32 of S, will it all combine? If more than 32 of S with 56 of Fe? There is found to be a definite quant.i.ty of each element in every chemical compound. Symbols would have no meaning if this were not so.

Write and explain the equation for the experiment with copper and sulphur, using names, symbols, and weights, as above.

CHAPTER V.

MANIPULATION.

17. To Break Gla.s.s Tubing.

Experiment 8.--Lay the tubing on a flat surface, and draw a sharp three-cornered file two or three times at right angles across it where it is to be broken, till a scratch is made. Take the tube in the hands, having the two thumbs nearly opposite the scratch, and the fingers on the other side. Press outward quickly with the thumbs, and at the same time pull the hands strongly apart, and the tubing should break squarely at the scratch.

To break large tubing, or cut off bottles, lamp chimneys, etc., first make a scratch as before; then heat the handle of a file, or a blunt iron--in a blast-lamp flame by preference--till it is red-hot, and at once press it against the scratch till the gla.s.s begins to crack. The fracture can be led in any direction by keeping the iron just in front of it. Re-heat the iron as often as necessary.

18. To Make Ignition-Tubes.

Experiment 9.--Hold the gla.s.s tubing between the thumb and forefinger of each hand, resting it against the second finger.

Heat it in the upper flame, slowly at first, then strongly, but heat only a very small portion in length, and keep it in constant rotation with the right hand. Hold it steadily, and avoid twisting it as the gla.s.s softens. The yielding is detected by the yellow flame above the gla.s.s and by an uneven pressure on the hands. Pull it a little as it yields, then heat a part just at one side of the most softened portion. Rotate constantly without twisting, and soon it can be separated into two closed tubes. No thread should be attached; but if there be one, it can be broken off and the end welded. The bottom can be made more symmetrical by heating it red-hot, then blowing, gradually, into the open end, this being inserted in the mouth. The parts should be annealed by holding above the flame for a short time, to cool slowly.

For hard gla.s.s--Bohemian--or large tubes, the blast-lamp or blowpipe is needed. In the blast-lamp air is forced out with illuminating gas. This gives a high degree of heat. Bulbs can be made in the same way as ignition-tubes, and thistle-tubes are made by blowing out the end of a heated bulb, and rounding it with charcoal.