A unit of luminous intensity used in Prussia, 19ᵗʰ century, the light from a cylindrical candle made of paraffin, with a diameter of 20 millimeters and a length of 314 millimeters, burning with a flame height of 50 millimeters. The wick consisted of 25 strands of twisted cotton thread.
According to Appleton, 1 Vereinskerze was approximately equal to 1.05 British standard candles or to 1.16 to 1.224 hefner.
Literally translated, the name means “union candle,” and it was sometimes referred to as the association candle.
The German Association of Gas and Water Industries adopted in 1868 as photometric candle a paraffine candle of 6 to the pound, having a uniform diameter of 20 mm.; its length is 314 mm., and its weight 83.6 grams. The melting-point of the paraffine employed is 55°C. The wick is made of a twist of 25 threads of cotton; a meter of wick weighs 668 mg. The illuminating power of the candle depends on the height of the flame; unity corresponds to a flame 50 mm. high.
The melting-point of paraffine is quite variable, and oscillates between 55° and 65°; it may even reach 80°, or fall to 44°. These variations in the melting-point oblige the manufacturers to add, in certain cases, from 10 to 15 per cent of stearine. It is necessary then, in order to have a constant candle, to be sure that its composition corresponds closely to the conditions of purity mentioned above.
A Treatise on Industrial Photometry with Special Attention to Electric Lighting.
Authorized translation from the French by George W. Patterson, Jr., and Merib Rowley Patterson.
New York: Van Nostrand Co, 1894.
Page 122. The first French edition, Traité de Photométrie Industrielle Spécialement Appliquée à L’éclairage électrique, was published in 1892.
Die deutsche (Vereins-)Paraffinkerze, welche unter Aufsicht des deutschen Vereins von Gas- und Wasserfachmännern nach festen Normen hergestellt wird, 20 mm im Durchmesser hat, und von welcher 12 Stück auf 1 kg kommen, soll bei einer Flammenhöhe von 50 mm benutzt werden.
The German verein candle, which is produced to strict standards under the supervision of the German Association of the Gas and Water Industries, is 20mm in diameter, and makes 12 pieces to the kilogram. It should be used with a flame height of 50mm.
Lehrbuch der Magnetischen und elektrischen Maasseinheiten, Messmethoden und Messapparate.
Stuttgart: Verlag von Ferdinand Enke, 1895.
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