Part II.-Description of Test to be applied by a Responsible Official before each Working Shift.

The lamp, while held in pure air, is turned to the "on" position by rotating the cover whilst holding the case containing the accumulator. After an interval of about 1 minute the lamp is turned from the "on" position to the "off" position, and is then immediately turned back to the "on" position. If the red bulb fails to be momentarily illuminated the lamp shall be deemed not to be in correct working order.

Part III.-Description of Test to be carried out by the Makers. The testing apparatus, the general design of which is shown in Plate II, consists of the following essential parts:

(1) Test cap consisting of a circular plate of insulating material provided with a screw thread for attachment to the cover of the alarm. Provided with a filament support to which terminals are attached for making connection to a 2-volt accumulator and a short tubulure to which a rubber tube can be attached.

(2) Alcohol gauge, so designed that it can be attached by means of a rubber tube or other suitable connection to the tubulure passing through the test cap. The tube connecting the alcohol gauge to the test cap is provided with a T-piece extension fitted with a stop-cock through which suction can be applied.

METHOD OF TESTING THE LAMP.

The contact plate is removed from the cover. The test cap, fitted with a filament similar in every respect to that used in the lamp in normal working, is screwed to the cover in place of the contact plate. A 2-volt accumulator is connected by means of wires to the terminals of the filament support. The alcohol gauge and T-piece are connected to the tubulure on the test cap. Suction is applied through the stop-cock until the bulb in the lantern is brought into circuit. The vacuum, in inches of alcohol, is observed at which the bulb is just brought into and thrown out of circuit. The lamp shall not be deemed to be in correct working order unless this figure corresponds to the original test figure recorded at the makers' works.

PLATE 2.

APPARATUS FOR TESTING THE RINGROSE (FIREDAMP ALARM) LAMP BY THE MAKER.

8. Explosives.

THE EXPLOSIVES IN COAL MINES ORDER OF THE
5TH MARCH, 1928.*

1928, No. 132.

In pursuance of the power conferred upon them by Section 61 of the Coal Mines Act, 1911, (a) and under the provisions of the Mining Industry Act, 1920, (b) the Board of Trade hereby make the following Order :

(1) The Explosives in Coal Mines Order of the 1st September, 1913, (c) as amended by the Explosives in Coal Mines Orders of subsequent dates, (d) shall be amended and shall take effect as if the explosives named and defined in the Schedule to this Order were named and defined in the First Schedule to that Order, and in all respects as if the Schedule to this Order formed part of the First Schedule to that Order.

(2) In the Schedule to the Explosives in Coal Mines Order of the 7th January, 1927, (e) the definition of the explosive Antifrost Penrhyn Powder shall be amended as specified in the Schedule to this Order.

(3) This Order may be cited as the Explosives in Coal Mines Order of the 5th March, 1928.

H. Douglas King,
Secretary for Mines.

Mines Department,

Dean Stanley Street,

Millbank, S.W.1.

5th March, 1928.

The Note giving a complete list of Permitted Explosives, prefixed to this Order as orignally issued, is printed at p. 324 below.

(a) 1-2 G. 5. c. 50.

(b) 10-1 G. 5. c. 50.

(c) PRINCIPAL ORDER.-S.R. & O. 1913 (No. 953) p. 633.

(d) For the amending Orders, see list in "Index to S. Powers and Rules and Orders in Force, Aug. 31, 1927 " at p. 126, and S.R. & O. 1927, pp. 164–76. (e) S.R. & O. 1927 (No. 10) p. 164.

22820

X

Schedule.

Polar Stomonal, consisting of the following mixture:

(1) That the explosive shall be used only when contained in a case of paper thoroughly waterproofed with (a) a mixture of ceresine and resin or (b) paraffin wax;

(2) That the explosive shall be used only with a detonator or electric detonator in which the explosive is contained in a copper capsule, and of not less strength than that known as No. 6 (i.e., the detonator or electric detonator to be used shall possess an effective detonative strength as great as, or greater than, that of one containing 15 grains of a composition consisting in every 100 parts by weight of 80 parts of fulminate of mercury and 20 parts of chlorate of potassium);

(3) That the greatest weight of the explosive which may be used in any one shot-hole shall not exceed 18 ounces;

(4) That the explosive has been made at the works of Nobel's
Explosives Company, Limited, at Ardeer, in the County of
Ayr;

(5) That the explosive is in all respects similar to the sample sub-
mitted to test on the 21st and 22nd days of December, 1927;
(6) That each cartridge, in addition to any marking required in the
Third Schedule to this Order, shall also be clearly marked with
the words "Not more than 18 ounces in any one shot-hole ";
and

(7) That in addition to the marking on the outer package required
by an Order of the Secretary of State, made under the
Explosives Act, 1875, (a) and in force for the time being, such
outer package shall bear the words "As defined in the List of
Permitted Explosives "; and, further, that each inner package
shall be clearly marked with the words "Permitted
Explosive, to be used only with not less than No. 6 detonator,"
and also with the name of the explosive, the name of the
manufacturer, the date and place of manufacture, and the
nature and proportion of the ingredients.

Four ounces of Polar Stomonal gave a swing of 2.47 inches to the Ballistic Pendulum compared with a swing of 3.27 inches given by four ounces of Gelignite containing 60 per cent. of nitro-glycerine.

(a) 38-9 V. c. 17.