Test.
1. (
Metallurgy.)
a. A
cupel.
b. A cupeling-hearth used in a refining-furnace where lead is separated from silver on a large scale.
The
test is an oval
iron frame containing a basinshaped mass of powdered bone-ash, which is brought to a consistence by a solution of pearlash.
The
test is fixed as a cupeling-hearth in the reverberatory furnace, and is subjected to a blast from a tuyere, which removes the floating oxide of silver and furnishes oxygen for its elimination from the alloy under treatment.
Pattinson's process has nearly superseded the plan just described.
See silver from lead, extract-ing.
2. The proof of condition of a sirup, which is generally a matter of practice with the sugar-boiler, but has been reduced to a system by
Payen.
See proof.
3. In chemistry, a body which is used to detect the presence of another body in solution, indicating the said presence by a peculiar behavior, or by producing a specific effect.
The behavior may be a change of color, as with litmus or turmeric paper.
The effect may be a change in the solution as to color, limpidity, evolution of gas, precipitation, heat, congelation, etc.
4. An apparatus for proving petroleum and similar hydrocarbon oils by ascertaining the temperature at which they evolve explosive vapors.
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Petroleum-test. |
Fig. 6317 consists of a cup
a provided with a loop for holding a thermometer, and a central perforated tube
c containing a wick.
The cup is partially filled with the oil, which flows through the perforations in the tube and saturates the wick.
The latter, being ignited, heats the oil to the vaporizing point and sets fire to the vapor.
[
2536]
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Carbon-oil fire-tester. |
In
Fig. 6318, the oil-vessel
H is placed in a water-bath
D provided with a non-conducting jacket, and heated from below.
Thermometers
M N dip into the water and oil vessels respectively.
The brand for igniting the vapor is carried by a pivoted lever
B operated by a spring-rod
S T. A cap is provided for preventing the vapor from being disturbed by currents of air, and a spigot for ensuring a uniformity in the level of the water and oil.
