In using the cell sudden variations of temperature should as far as possible be avoided. The form of the vessel containing the cell may be varied. In the H form, the zinc is replaced by an amalgam of 10 parts by weight of zinc to 90 of mercury. The other materials should be prepared as already described. Contact is made with the amalgam in one leg of the cell, and with the mercury in the other, by means of platinum wires sealed through the glass. Order in BOARD OF TRADE ELECTRICAL STANDARDIZING LABORATORY. 1. The Board of Trade are now prepared to receive electrical instruments for examination or testing at their Electrical Standardizing Laboratory at 8, Richmond Terrace, Whitehall (v). 2. The only classes of electrical instruments which can be received at present for examination or testing are such as are intended for the measurement of electrical pressure, current, power, quantity, energy, or resistance. 3. Meters for the measurement of quantity or energy cannot be received with a view to certification for use in connection with the supply given by Undertakers under Electric Lighting Orders. 4. Instruments may be personally delivered at the Laboratory for testing between the hours of ten a.m. and two p.m., or may be forwarded by post or other delivery. In every case instruments must be accompanied by a form of application which may be obtained from the Laboratory. 5. The Board of Trade, or the officers of the Board, will not be responsible for any damage to any instrument, either in transport or while at the Laboratory, nor for any loss sustained in consequence of the time that may elapse before the instrument is returned. 6. Instruments will not be received which are not plainly marked with the name of the manufacturer and an identification number. 7. Instruments will not be returned until all money due for fees or other charges incurred has been paid. 8. Every instrument submitted must be provided with suitable terminals or leads, so that it can be readily connected to the testing circuit without soldering. 9. All indicating instruments must have their dials plainly marked with a suitable scale, which may be of equal or of unequal divisions. 10. The points of testing required must be specified in electrical units (volts, amperes, etc.), stating whether alternating or continuous or both, and not in numbers referring to the scale on the instrument. (v) Application for examination or testing of electrical instruments at the Board of Trade Electrical Standardizing Laboratory must be made on a printed form provided by the Board of Trade for the purpose. Other forms are provided in connection with the examination or testing; and these are procurable at the Board of Trade. 11. The Laboratory charges on any instrument may be paid by Post Office Order or Postal Order if the instrument is to be forwarded by post or other delivery, or in cash by the person authorized to remove the instrument. All payments should be made to the Assistant-Secretary, Finance Department, Board of Trade, Whitehall Gardens, S.W. 12. A certificate of test will be forwarded by post after the instrument has been removed. 13. The attached scale of fees for examination or testing of electrical instruments for the measurement of resistance, current, or electrical pressure, has been approved by the Treasury under Section 8 of "The Weights and Measures Act, 1899." T. H. W. PELHAM, Assistant-Secretary, Board of Trade. October 7, 1897. BOARD OF TRADE ELECTRICAL STANDARDIZING LABORATORY. TABLE OF FEES FOR EXAMINATION OR TESTING OF ELECTRICAL INSTRUMENTS FOR THE MEASUREMENT OF RESISTANCE, CURRENT, OR ELECTRICAL PRESSURE. 1. For an instrument intended to be used as a sub-standard and submitted for special examination and testing If required to be kept under observation for a period longer than one month; for each additional month or part of a month .. 2. For ordinary direct reading instruments: for testing at three points: Voltmeter for continuous pressure only :Not exceeding 200 volts : Exceeding 20 and not exceeding 2,000 volts Extra fee if tests are to be made at one stated frequency of Voltmeter for both continuous and alternating pressures, or for £ 8. d. 300 100 050 06 0 0 7 6 076 0 10 0 020 0 10 0 050 076 0 10 0 0 15 0 Ammeter for alternating current only : Not exceeding 500 amperes Extra fee if tests are to be made at one stated frequency of .0 20 Table of £8. d. 2. For ordinary direct-reading instruments, etc.—continued. Not exceeding 500 amperes Exceeding these limits up to 2,000 volts, or 2,500 amperes For each point tested beyond three points in any direct-reading In the case of any direct-reading instrument if arranged to Extra fee for every record verified 3. For instruments reading by an adjustment to zero, an increase 4. For determining the constants of integrating meters (w) at Up to a maximum rate exceeding 25 and not exceeding 100 Up to a maximum rate exceeding 100 and not exceeding 500 amperes.. 1 0 0 Up to a maximum rate exceeding 500 and not exceeding 2,000 If to be tested at two frequencies, or at one frequency of 0 15 0 Up to a maximum rate exceeding 25 and not exceeding 100 If to be tested at one frequency 0 15 0 If to be tested at two frequencies, or at one frequency of 126 Up to a maximum rate exceeding 100 and not exceeding 500 If to be tested at one frequency 1 0 0 If to be tested at two frequencies, or at one frequency of 1 10 0 Energy meter, continuous current only:- 0 15 0 Up to a maximum rate exceeding 10,000 and not exceeding 1 0 0 (w) These instruments will only be accepted for testing if intended to be used as sub-standards or for scientific purposes. £ 8. d. 4. For determining the constants, etc.-continued. Table of Energy meter, continuous current only-continued. Up to a maximum rate exceeding 50,000 and not exceeding 200,000 watts Energy meter, alternating current (x) :— Up to a maximum rate of 20,000 watts: If to be tested at one frequency .. If to be tested at two frequencies, or at one frequency of Up to a maximum rate exceeding 20,000 watts and not If to be tested at one frequency If to be tested at two frequencies, or at one frequency of For each rate tested beyond three rates in any meter an 5. For testing resistances and standard cells : For a resistance coil of not less than 1 ohm resistance to an accuracy of 0.01 per cent. 1 10 0 100 1 10 0 1 10 0 250 0 5 0 For a resistance coil of resistance between 1 ohm and 100 ohm to an accuracy of 0.1 per cent. 050 For a box of resistance coils with Wheatstone bridge, Post Office or dial pattern, to an accuracy of 0·1 per cent., per coil tested With a minimum fee of For a coil of standard form to highest accuracy obtainable at one temperature For determining the E.M.F. of a Clark's standard cell at one temperature For testing resistances and standard cells at two different and determined temperatures the fee to be charged will be twice that specified above, with an additional charge of 58. for each instrument. 006 0 10 0 050 In the case of all the above-mentioned tests, except tests of standard instruments, integrating meters, and resistances, the fees charged will be reduced by one-third if from six to twelve similar instruments are submitted at the same time, and by one-half if the number exceeds twelve. CONDITIONS UNDER WHICH INSTRUMENTS ARe received foR EXAMINATION OR 1. The only class of electrical instruments which can be received at present for examination or testing are such as are intended for the measurement of electrical pressure, current, power, quantity, energy, or resistance. 2. Meters for the measurement of quantity or energy cannot be received with a view to certification for use in connection with the supply given by undertakers under Electric Lighting Orders. () No greater alternating current than 500 amperes can be measured. |