CHAPTER XIII.

BOILING POINTS FRACTIONAL

DISTILLATION-SPECIFIC HEAT-

ATOMIC HEAT-HEAT OF COMBINATION-CALORIFIC INTENSITY.

Introduction, 1228-Heat and temperature, 1230-Thermoscopic in-

struments, 1232-Construction of the mercurial thermometer, 1235

-Testing of a thermometer, 1252-Formulæ for the conversion of

degrees of one scale into those of another, 1254-Exercises-Boiling

points, 1255-Kopp's law of the boiling points, 1261-Exercises

-Fractional distillation, 1279-Specific heat, 1286-Methods

employed for determining the specific heat of solids and liquids,

1290-Measure of the sensible heat absorbed by a body, 1291-

Exercises-Description of Regnault's method for determining the

specific heat of solids and liquids, 1302-Specific heat of a body not

a constant quantity, 1316-Specific heat of gases, 1320-Table of

the specific heat of gases, 1322-Atomic heat of bodies, 1323-

Relation between the specific heats and atomic weights of the

elementary bodies, 1326-Table of the specific and atomic heats of

the elements. Atomic heats of compound bodies, 1332-Develop-

ment of heat by chemical action, 1335-Description of Dr. Andrews'

method, 1343-Combination of gaseous bodies with oxygen, 1349—

Exercises-Combination of oxygen with solid and fluid bodies, 1354

-Exercises-Table of the heat developed during the combination

of bodies with oxygen, 1367-Tables of the heat developed during

the combination of bodies with chlorine, bromine, and iodine, 1368

-Influence of dimorphism on the heat evolved, 1372-Heat deve-

loped on the combination of acids and bases, 1373-Table of heat

evolved during metallic precipitations, 1378-Heat evolved on the

combination of acids with water, 1382-Heat evolved on the com-

bination of a salt with water, 1384-Heat evolved on the combus-

tion of polymeric compounds, 1385-Cold produced by chemical

decompositions, 1391-Exceptions, 1396-Calorific intensity, 1397—

Exercises-Calorific intensity of fuel, 1403-Exercises-Thomson's

apparatus for determining the absolute heating power of fuel, 1407

-On the burning of fuel, 1409.

Pages 541 to 634

CHAPTER XIV.

DIFFUSION OF LIQUIDS-DIALYSIS-OSMOSE.

Introduction, 1413-Characters of liquid diffusion, 1423-Diffusion of

various salts and other substances, 1428-Diffusibility of acids, 1435

-Diffusion of mixed salts, 1447-Separation of salts of different

bases by diffusion, 1448-Decomposition of salts by diffusion, 1449

-Diffusion of double salts, 1456-Diffusion of one salt into the

solution of another salt, 1461-Diffusion of salts of potash and

ammonia, 1467-Crystalloid and colloid substances, 1470-Effect of

temperature on diffusion, 1483-Diffusion of crystalloids through

colloids, 1484-Dialysis, 1489-Distinction between crystalloids and

colloids, 1496-Application of dialysis, 1507-Osmose, 1527.

Pages 634 to 697

CHAPTER XV.

ON CHEMICAL ANALYSIS BY SPECTRUM OBSERVATIONS.

Coloured flames, and their utility in chemical analysis, 1537-Spectrum

analysis, 1539-Spectra of the metals of the alkalies and alkaline

earths, 1540-Description of the apparatus for spectrum analysis,

1541-Delicacy of the spectrum reactions of bodies, 1513-Increase

of luminous lines with an increase of temperature, 1545-Do the

different compounds of the same metal produce lines of the same

colour? 1546-Do any of the lines of the different metals coincide?

1549-Are the lines of any substance obliterated or altered by the

presence of another substance? 1550-Spectra of the metalloids,

1551-Spectra of solids and vapours contrasted, 1552-Relation

between the absorption and emission of heat and light by bodies,

1553-Dark lines in the solar spectrum, 1554-The dark lines vary

with the nature of the luminous source, 1556-The solar spectrum,

and the spectrum of an incandescent solid or liquid, contrasted,

1557 Chemical constitution of the sun's atmosphere, 1558-

Chemical constitution of the atmosphere of the fixed stars, 1559.

APPENDIX N.- Arrangement of the spectrum apparatus, 1560.

Pages 698 to 716

APPENDIX I.

Weights and measures, page 717-Table I. Specific gravity and absolute

weight of several gases, page 720-Table II. Weight of one cubic

centimetre of air at different temperatures, page 721-Table III.

Conversion of degrees on the Centigrade scale into Fahrenheit

degrees, page 723
· Pages 717 to 725

APPENDIX II.

Selections from the Examination Papers of the Museum of Irish

Industry; Royal School of Mines; London University; Trinity

College, Dublin; Queen's Colleges of Cork and Belfast; Queen's

University in Ireland; Department of Science and Art Exami-

nation in Chemistry for Science Certificates and Science Schools.

Pages 726 to 771

THE SECOND STEP IN CHEMISTRY.

CHAPTER I.

PROPERTIES OF MATTER.

Specific gravity of gases and vapours, 1. Exercises. Expansion of matter by heat, 5. Correction of gases for temperature, 12. Exercises. Compressibility of matter, 16. Elasticity of matter, 25. Correction of gases for pressure, 42. Exercises. Liquefaction, 43. Vaporization, 45. Correction of gases for the tension of aqueous vapour. Exercises.

1. SPECIFIC GRAVITY OF GASES AND VAPOURS.-Gases and vapours differ in their densities, or specific weights. 2. Atmospheric air, at 60° F., and the barometer standing at 30 inches, is employed as the standard of comparison for gases and vapours. One hundred cubic inches of air weigh, according to the latest researches by Regnault, 30.935 grains at this temperature and pressure. Air is therefore about 814 times lighter than water, as 100 cubic inches of water weigh 25246'0 grains.

3. If the specific gravity of a gas or vapour be known, the absolute weight of a given volume of it can be determined. To accomplish this, we have simply to multiply the weight of an equal volume of air by the specific weight of the gas or vapour; the product will be the weight of the volume, at the standard temperature and pressure of the gas or vapour.

Example. What is the weight of 100 cubic inches of hydrogen, its specific gravity being '0694?

30-935 × 0694 = 2·147 grains weight of 100 cub. in. of H. 4. If it be desired to find the volume of a given weight

The standard temperature and pressure adopted on the Continent differs from that employed in England. The temperature is 0° C. = 32° F. ; the pressure is 760 millimetres = 29-922 inches.

B

of any gas or vapour, the weight of some volume (say a cubic inch) of the gas or vapour must first be ascertained by the preceding rule; then the given weight must be divided by the weight of the cubic inch; the quotient will be the volume in cubic inches of the given weight of the gas, at the standard temperature and pressure.

Example.-What is the volume of 2·147 grains of hydrogen, its sp. gr. being 0.0694 P

1. What is the weight of a cubic inch of oxygen, its sp. gr. being 1.1057 P

2. What is the weight of a cubic inch of nitrogen, its sp. gr. being 0.9713 P

3. What is the weight of a cubic inch of carbonic acid, its sp. gr. being 1·529 ?

4. What is the weight of a cubic inch of gaseous ammonia (NH3), its sp. gr. being 0.59?

5. What is the volume of 54 grains of chlorine, its sp. gr. being 2.44?

6. What is the volume of 45 grains of carbonic oxide, its sp. gr. being 0·967 ?

7. How many cubic inches of oxygen would be obtained from 100 grains of chlorate of potash ?

of

Oxygen gas is frequently prepared by igniting peroxide manganese. The following decomposition occurs :

3 Mn 0,= Mn, 0, + 20.

8. How many cubic inches of oxygen would be obtained from 400 grains of a manganese ore containing 70 per cent. of the peroxide, the equivalent of manganese being 27.6 ?

Gunpowder consists of a mixture of carbon, sulphur, and nitrate of potash. The gunpowder which is most powerful as a propelling agent, is found to be that which Corresponds most nearly in composition to the formula,— KO, NO, + 3C + S.

The theoretical decomposition of a powder of this description would be represented by the equation,