SECTION II.

1. The specific gravity of nitrogen, referred to that of hydrogen as unity, is 14. What is the specific gravity of ammonia referred to that of hydrogen as unity? Give the method of calculation.

Solution.

Hydrogen and nitrogen have the same combining volume, therefore the weights of their volumes are in the ratio of their equivalents.

Again, 3 vols. of H and 1 vol. of N combine, and condense into 2 vols. of ammonia, NH..

:

3. A salt has been found to contain in 100 parts:

What is the formula of the salt? The following

equivalents to be used:

Solution.

Divide the quantity of each element by its equivalent:

The salt is therefore Mg, NPHis O20.

The P is doubtless in the state of PO,, the N in the

form of NHO, and the Mg as MgO.

The formula may therefore be represented as

H

2 MgO,NH,O,PO, † 12HO; or, Mg,NH,,PO, + 12HO.

SECTION III.

1. Describe a process by which pure oxygen gas may be prepared from atmospheric air.

2. Give an outline of the manufacture of nitric acid, and state the quantities of sulphuric acid (HSO), nitrate of potassium (KNO), or nitrate of sodium (NaNO), which are required to produce 1 lb. of nitric acid (HNO,).

Solution.

H = I; 0 = 8; N = 14; S = 14; K = 39; Na = 23. Formula showing the production of nitric acid :

(2.) or NO, + 2HSO, HNO, +or (SO, + HSO.

K

=

K

In the first, sulphate of potash or soda is left in the retort; in the second, bisulphate of soda or potash is left. According to the first formula 1 eq. of HSO, is required for the decomposition of 1 eq. of NaNO, or KNO.

So that 49 parts by weight of HSO, will produce from 77 parts of NaNO,, or 93 parts of KNO, 63 parts of HNO. The quantities of each of these required for the production of 1 lb. of HNO, may be easily determined by proportion:

HNO.. HNO。. HSO..

HSO..

KNO..

KNO

:: 93 : I lb. 7.619 ozs.

According to the second formula, these quantities remain the same with the exception of HSO,, of which double the above quantity is employed, viz., 12°4 ozs. X 21 lb. 8.8'ozs.

3.

.How many volumes of oxygen gas are required to burn one volume of marsh gas, and one volume of olefiant gas : and how many volumes of carbonic acid gas are produced by their combustion?

Solution.

By volume C, H, is composed of 4 vols. H and 2 vols. C vapour (hypothetical) condensed into 2 vols.

So that I vol. of C, H, contains 1 vol. C vapour, + 2 vols. H.

Now CO, contains equal volumes of C vapour (hypothetical) and of O. Therefore 1 vol. C vapour requires I vol. O to unite with it so as to form 1 vol of CO..

Again, HO contains H and O in proportion of a vols. H to I vol. O.

Therefore 2 vols. I require for complete combustion 1 vol. O.

So that I vol. C, H,, containing 1 vol. C and 2 vols. H, requires altogether 2 vols. O for complete combustion, from which I vol. of CO, is formed.

Again, C, H, is composed, by volume, of 4 vols. C vapour and 4 vols. H condensed into 2 vols.

So that i vol. C, H, contains 2 vols. C vapour + 2 vols. H.

While the H then remains the same as in C, H, the volume of the C is doubled, requiring twice as much O or 2 vols.

Quantity of O required by the 2 vols. H=1 vol.

So that the total quantity of O required is 3 vols., of which 2 vols. combine with the C, forming 2 vols. CO.

SECTION IV.

1. Describe the chemical reactions involved in the etching of glass.

2. State the succession of processes by which aluminium may be extracted from alum shale..

3. What is meant by the term disintegration?

Give

an outline of the several phases of the disintegration of granite,

PRACTICAL EXAMINATION IN ANALYSIS.

1. Qualitative analysis of a mixture consisting of two acids and two bases soluble in water or acids.

2. Qualitative analysis of a mixture consisting of two acids and two bases partly or entirely insoluble in water and acids.

3. Qualitative analysis of more complex mixtures.

State the method of examination in detail, and tabulate the result of the analysis, pointing out particularly the substances of which traces only have been found.