872

THE NEW ZEALAND GAZETTE.

[No. 26

at a right angle, for receiving a long bulb thermometer, to
indicate the temperature of the water. It is also provided
with a funnel, an overflow pipe, and two handles.

The water bath rests upon a tripod stand, which is fitted
with a copper cylinder or jacket (24 B.W.G.) 6½ in. diameter,
so that the bath is surrounded by an enclosed air-space,
which retains and regulates the heat. One of the legs of
the stand serves as a support for a spirit-lamp, which is
attached to it by a small swing bracket. The distance of
the wickholder from the bottom of the bath is 1 in. The
clockwork arrangement by which, during the operation of
testing, the slide is withdrawn and the test-flame dipped into
the cup and raised again as the slide is replaced is provided
with a ratchet-key for setting it in action for each test, and
with a trigger for starting it each time that the test-flame is
applied. From the beginning to the end of the movement
of the slide the time taken is to be exactly 2 seconds.

N.B.—When gas is available it may be conveniently used
instead of the oil-lamp, and for this purpose a test-flame
arrangement for use with gas may be substituted.

II.—DIRECTIONS FOR PREPARING AND USING THE TEST
APPARATUS.

1. Preparing the Water Bath.

The water bath is filled by pouring water into the funnel
until it begins to flow out at the overflow-pipe. The tem-
perature of the water at the commencement of each test,
as indicated by the long bulb thermometer, is to be as
follows :—

(a) 130 degrees, when a flashing-point at or about 73 degrees
is to be observed.

(b) 160 degrees, when a flashing-point at or about 100
degrees is to be observed.

(c) 180 degrees, when a flashing-point at or about 150
degrees is to be observed.

This is attained in the first instance by mixing hot and
cold water, either in the bath or in a vessel from which the
bath is filled, until the thermometer which is provided for
testing the temperature of the water gives the proper indica-
tion, or the water is heated in the bath by means of a spirit-
lamp or gas arrangement until the required temperature is
indicated.

2. Preparing the Test-lamp.

(a) The test-lamp is fitted with a piece of cylindrical
wick of such thickness that it fills the wick-holder, but may
be readily moved to and fro for the purpose of adjusting the
size of the flame. In the body of the lamp, upon the wick
which is coiled within it, is placed a small tuft of cotton-
wool moistened with petroleum, any oil not absorbed by
the wool being removed. When the lamp has been lighted
the wick is adjusted by means of a pair of forceps or a pin
until the flame is of the size of the bead fixed on the cover of
the oil-cup.

Should a particular test occupy so long a time that the
flame begins to get smaller through the supply of the oil in
the lamp becoming exhausted, three or four drops of petro-
leum are allowed to fall upon the tuft of wool in the lamp
from a dropping-bottle or pipette provided for the purpose.
This can be safely done without interrupting the test.

(b) When using gas for testing, the jet is to be lighted
and then adjusted by means of the tap controlled by means
of a screw pinch-cock or fine tap until the flame is the size
of the bead fixed on the cover of the oil-cup.

III.—FILLING THE OIL-CUP.

Before the oil-cup is filled the lid is to be made ready by
being placed upon the cup—i.e., the round bulb thermometer
is to be inserted into the socket so that the projecting rim
of the collar with which it is fitted touches the edge of the
socket, and the test-lamp is to be placed in position. The
oil-cup is to be cooled when necessary to a temperature not
exceeding—

(a) 60 degrees, when a flashing-point at or about 73
degrees is being observed ;

(b) 85 degrees, when a flashing-point at or about 100
degrees is being observed ;

(c) 135 degrees, when a flashing-point at or about 150
degrees is being observed ;

by placing it bottom downwards in water at a suitable
temperature. The oil-cup is now to be rapidly wiped dry,
placed on a level surface in a good light, and the oil to be tested
is poured in without splashing until its surface is level with
the point of the gauge which is fitted in the cup. The lid is
then put on the cup at once and pressed down so that its
edge rests on the rim of the cup.

IV.—APPLICATION OF THE TEST.

1. The water bath, with its thermometer in position, is
   placed in some locality where it is not exposed to currents
   of air, and where the light is sufficiently subdued to admit
   of the size of the entire test-flame being compared with that
   of the bead on the cover. The cup is carefully lifted, without
   shaking it, and placed in the bath, the test-lamp is lighted,
   and the clockwork wound up by turning the key. The
   thermometer in the oil-cup is now watched, and the clock-
   work is set in motion by pressing the trigger when the tem-
   perature has reached—

(a) 63 degrees, when a flashing-point at or about 73
degrees is being observed.

(b) 90 degrees, when a flashing-point at or about 100
degrees is being observed.

(c) 140 degrees, when a flashing-point at or about 150
degrees is being observed.

If no flash takes place the clockwork is at once rewound and
the trigger pressed at the next higher degree, and so on at
every degree rise of temperature until the flash occurs.

2. When a flashing-point at or about 115 degrees is being
   observed the air-chamber is to be filled to a depth of 1½ in.
   with cold water before the oil-cup containing the oil to be
   tested is placed in position.

3. The temperature at which a flash occurs, if not within
   8 degrees of the temperature at which the testing was com-
   menced, is the observed flashing-point of the oil, and by
   correction of the observed flashing-point for atmospheric
   pressure, as hereinafter described, the true flashing-point is
   obtained.

4. If, however, the flash takes place at any temperature
   within 8 degrees of the temperature at which the testing
   was commenced, the test is to be rejected, and the whole
   operation of testing is to be repeated with a fresh portion of
   the sample, the testing, however, to begin at 10 degrees
   lower than the temperature at which the flash has been
   previously obtained. If necessary, this procedure shall be
   repeated with fresh portions of oil until a flash has been
   obtained at a temperature not within 8 degrees of the tem-
   perature at which the testing was commenced.

5. The temperature at which the last-mentioned flash
   occurs is the observed flashing-point of the oil, and by
   correction of the observed flashing-point for atmospheric
   pressure, as hereinafter described, the true flashing-point is
   obtained.

6. In repeating a test a fresh sample of oil must always
   be used, the tested sample being thrown away, and the cup
   must be wiped dry from any adhering oil, and cooled, as
   already described, before receiving the fresh sample.

7. If in any case no flash has occurred when a temperature
   has been reached which is not within 8 degrees of the tem-
   perature at which the testing was commenced, and which,
   after correction for atmospheric pressure, is not less than
   73 degrees, and the tests are not required to be continued,
   the oil shall be deemed to have a true flashing-point of not
   less than 73 degrees.

8. If no flash has occurred when a temperature has been
   reached which is not within 8 degrees of the temperature at
   which the testing was commenced, and which, after correc-
   tion for atmospheric pressure, is not less than 100 degrees,
   and the tests are not required to be continued, the oil shall
   be deemed to have a true flashing-point of not less than
   100 degrees.

9. In the same manner, if no flash has occurred when a
   temperature has been reached which is not within 8 degrees
   of the temperature at which the testing was commenced,
   and which, after correction for atmospheric pressure, is not
   less than 150 degrees, and the tests are not required to be
   continued, the oil shall be deemed to have a true flashing-
   point of not less than 150 degrees.

V.—CORRECTION FOR ATMOSPHERIC PRESSURE.

As the flashing-point of an oil is influenced by changes in
atmospheric pressure to an average of 1·6 degrees for every
inch of the barometer, a correction of the observed flashing-
point is necessary whenever the barometer does not stand at
30 in. This correction is to be made in the following manner :

If the barometer stands at less than 30 in. (the normal
height of the barometer), add to the observed flashing-point
1·6 times the difference (measured in inches) between the
actual and normal barometer. If the barometer stands
above 30 in. deduct from the observed flashing-point 1·6
times the difference between the actual and normal barometer.

The nearest whole number to the result of this correction
is to be taken as the corrected flashing-point, and if the
result is exactly midway between two whole numbers the
higher whole number is to be taken.

For example: Suppose an oil has an observed flashing-
point of 72 degrees, the barometer being 27·1 in., then the