Man, £2; Woman, £1; 2 Boys, £1: 10s.; Girl, 10s.

9. The greatest common measure of (2) and (3) is

x2 + 8x + 15

And greatest common measure of x2 + 8x + 15 and (1) is x+3 Answer.

Examiners-PROF. DEBUS, Ph. D., F.R.S. and PROF. DEWAR, M.A., F.R.S.

1. Why do we call Hydrogen and Oxygen chemical elements, and why do we consider Water to be a compound of these two elements?

2. How could you distinguish a mechanical mixture of one volume of Nitrogen and three volumes of Hydrogen from Ammonia-the chemical compound of the two gases?

3. How would you prove that in the combustion of phosphorus the oxygen of the atmosphere enters into chemical combination with the combustible matter?

D 3

4. Sulphur is known in at least three allotropic modifications. Describe the preparation and the characteristic properties of each modification.

5. Explain the formation of Sulphuretted Hydrogen (H,S) from ferrous sulphide (Fe S) and hydric chloride (H Ci) by means of symbols. What products are formed by the combustion of Sulphuretted Hydrogen in air? How many C.C. of Oxygen are required for the combustion of 100 C.C. of Sulphuretted Hydrogen?

6. How many C.C. of Carbonic Acid (CO2) are produced by the complete combustion of 12 grammes of Carbon in 22380 C.C. of Oxygen? How many C.C. of Carbonic Acid can be generated from 100 grammes of Marble by an aqueous solution of Hydric Chloride?

[Ca

=

40; O

=

16; C = 12.]

How could you distinguish Carbonic Acid from Nitrogen?

ANSWERS TO THE QUESTIONS.

1. Because we cannot by any known process divide them into different bodies other than Oxygen and Hydrogen.

When Oxygen and Hydrogen burn slowly, or when mixed together in the proper proportions and light is applied, water is formed.

2. Ammonia has strong smell, fumes with Hydrochloric Acid, and dissolves very freely in water.

The contrary is true for the mechanical mixture.

3. Phosphoric pentoxide is able to take away the elements of water from substances which contain them.

4. The first form may be obtained artificially by allowing the solution of sulphur in chloride of sulphur to evaporate spontaneously. The second by melting two or three kilogrammes of sulphur, and allowing it to solidify at the surface. The third is produced by the action of greater

heat.

All the varieties of sulphur are soluble to a small extent in boiling anhydrous alcohol. The crystals of the first form undergo no change in air.

Its products of its combustion in air are steam and sulphur dioxide. 6. Carbonic Acid is a compound of 32 of O with 12 of C by weight. 22380 CC of O 32.083960 grs., i. e., just sufficient to unite with the 12 of C. to form 45 of CO2.

=

i. e., 100 parts by weight liberate 44 parts by weight of CO2, then there will be 44 grains of CO, formed, which equals 22380. C.C.

Lime water becomes turbid when poured into Carbonic Acid, and remains clear when poured into Nitrogen.

NATURAL PHILOSOPHY.

Examiners-PROF. W. G. ADAMS, M.A., F.R.S., and WILLIAM GARNETT, ESQ., M.A. [Only Eight Questions are to be answered, of which at least Two must be selected from Section 4.]

A.

1. Explain a convenient method of representing geometrically the velocity of a body moving according to a known law, and the distance passed over by it.

Employ the method to find the distance traversed in ten minutes by a train which has a velocity of twenty miles an hour, and which has its speed diminished at a uniform rate to five miles an hour.

2. Define Force, and explain how it is measured.

What units of force are employed in this country for scientific purposes? How would you determine the number of British absolute units of force in the weight of a pound?

3. A particle is acted upon by any number of forces in one plane. How would you express the conditions necessary for its equilibrium?

If the system of forces be reduced to three, what simple geometrical relation must exist between their magnitude and their directions?

4. A particle, whose mass is M pounds, moves from rest under the action of a force of P units, which is constant in magnitude and direction. How far will the particle move in N seconds, and what space will it describe in the nth second?

If the force be the weight of the body, and the particle traverse 176.99 feet during the 6th second of its motion, find the value of "g."

5. A body is capable of turning freely about its centre of gravity, which is fixed. If the body be displaced in any manner, subject to this condition, and be then left to itself, how will it behave?

A uniform rod, AB, is 4 feet long and weighs 3lbs. One pound is then attached to the end A, 2lbs. at a point distant 1 foot from A, 3lbs. at 2 feet from A, 4lbs. at 3 feet from A, and 5lbs. at the end B. Find the distance from A of the Centre of Gravity of the system.

B.

6. A quantity of heavy liquid is at rest under the action of gravity, its surface extending over a considerable area. State what you know respecting

(1) The form of the free surface;

(2) The relation between the pressures in different directions at any point;

(3) The magnitude of the pressure at different depths below the

surface.

How might the value of "g" in different latitudes be determined by means of a delicate pressure gauge immersed to a constant depth, say 20 feet, beneath the surface of still water?

7. A cubic foot of water weighs 1,000 ounces. A cylindrical test-tube is held in a vertical position and immersed mouth downwards in water. When the middle of the tube is at a depth of 32.75 feet it is found that

the water has risen half way up the tube. Find the atmospheric pressure in pounds weight per square inch.

8. Define specific gravity.

Suppose that a cubic foot of air weighs 1.2 oz., and a cubic foot of water 1,000 oz. A balloon so thin that the volume of its substance may be neglected, contains 1.5 cubic feet of coal-gas, and the envelope, together with the car and appendages, weighs 1 oz. The balloon just floats in the middle of the room, without ascending or descending: find the specific gravity of coal-gas (1) compared with air, (2) compared with water.

9. Explain the principles on which the use of Bramah's press depends; and show how to find the relation between the power and the pressure when the areas of the pistons are given.

If a pressure of 1 ton is produced by a power of 5lbs., and the diameters of the pistons are in the ratio of 8 to 1, find the ratio of the lengths of the arms of the lever employed to work the piston.

10. State the laws of Reflexion of Light.

Two mirrors are placed parallel to one another, and a luminous point is placed midway between them. Show how to draw (accurately) the path of a ray of light which, after undergoing 3 reflexions at 1 mirror and 4 at the other, enters an eye also placed midway between the mirrors, but at some distance from the source of light.

11. On a moonlight night, when the surface of the sea is covered with small ripples, instead of an image of the moon being seen in the sea, a long band of light is observed on the surface of the sea extending towards the point which is vertically beneath the moon. Account for this phenomenon in accordance with the laws of reflexion, illustrating your explanation by a figure.

12. What is the centre of a lens? Under what circumstances is the centre of a lens midway between its surfaces ?

Two equal lenses are placed side by side in the same plane, with their centres 3 inches apart. Two objects of the same size and shape, but of different colours, are placed behind the lenses at a distance of twice its focal length from each lens, and with their centres 6 inches apart, the line joining the centres of the objects being parallel to that joining the centres of the lenses. How will the images be situated, and what will be seen by an observer situated at a considerable distance in front of the lenses ?

13. Define the Coefficient of Linear Expansion of a substance.

Describe an experiment which shows that the coefficient of expansion of some metals is much greater than that of others.

Explain the construction of a (compensating) chronometer balancewheel.

14. What do you understand by a Unit of Heat ?

How would you determine experimentally the number of units of heat required to convert 1 lb. of water at 100° C. into steam at the same temperature? Describe fully the details of the experiment.

15. Define Temperature.

State and explain the effect on the temperature of a quantity of gas of suddenly compressing it, or of suddenly allowing it to expand.

16. Describe an experiment which shows that water is a very bad conductor of heat.

Good radiators are also good absorbers of radiation incident upon them. How would you prove this experimentally?

If a piece of glass and a piece of iron be raised to a red heat in a fire, both appear of the same colour as the coals; but when carried into a dark room, the hot iron appears much brighter than the glass. Account for this.

ANSWERS TO QUESTIONS.

Eight Questions have been selected.

2. Whatever is capable of producing motion in a body, or any change in the motion of a body, is termed force. Forces are represented by straight lines.

"Absolute" and "invariable."

If the force of gravity on a body weighing M pounds causes it to acquire in a second a velocity of g feet per second, this force equals Mg. Pound is the unit of mass, and the foot and second the units of space and time.

3. When any number of forces act upon the same body, their united effect may be such that no motion ensues; the forces are said to be in equilibrium.

The magnitude of each force is represented by that side which is parallel to its direction.

5. Take a triangular plate movable about an axis of rotation O, and let G be the centre of gravity. The centre of gravity must be either above or below the axis. In the first case the effect will cause it to fall further away; in the second case it tends to restore the body to the position of equilibrium.

In the first case the equilibrium is unstable, in the second case it is stable.

12. Every ray whose direction on emergence is parallel to its direction before entering the lens must pass through a certain point in traversing the lens that point is called the centre of the lens.

13. The coefficient of linear expansion is the elongation of the unit of length of a body when its temperature rises from zero to one degree. Ramsden and Roy's method.

On the circumference of the balance or wheel compensating strips are fixed, of which the more expansible metal is on the outside, and at the end of these are smaller masses of metal. When the radius is expanded by heat, the small masses are brought nearer the centre in consequence of the curvature of the strips, and as they can be fixed in any position, they are easily arranged so as to compensate for the expansion of the balance.