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Stirrer: Magnetic Stirrer, a Turning Horseshoe Magnet under a Free Magnet Rod (Rosinger, US 2,350,534, 1944)

Arthur Rosinger · Public domain (US patent drawing)

أنشأه

Penny

3. نوفمبر 2026

Stirrer: Magnetic Stirrer, a Turning Horseshoe Magnet under a Free Magnet Rod (Rosinger, US 2,350,534, 1944)

The magnetic stirrer of the chemistry lab. A small motor in a box spins a horseshoe magnet just under the thin lid. A little magnet rod sealed in an inert shell lies loose in the flask on top and spins with it, stirring the liquid into a deep vortex with nothing poking through the neck, so the flask can stay closed, under pressure or vacuum. Result: a stirrer for laboratory liquids, speed set by a rheostat. Source: A. Rosinger, US 2,350,534 (1944). Unknown: sizes, the motor and the magnet alloys. Picture: the patent drawing.

متوسط

Unknown

التعليمات

Build the box

Make a box with a bottom, side walls and a removable top, all of non-magnetic material. Make the top as thin as you can. Not given: the material, sizes.

المواد لهذه الخطوة:

مادة غير معروفة1 non-magnetic box

الأدوات المطلوبة:

أبعاد غير معروفة

Mount the motor and magnet

Fix an electric motor in the middle of the box with its shaft upright, held by bands round its housing whose arms are screwed to the side walls. Fix a strong horseshoe permanent magnet on the shaft, poles up, so its pole faces turn as close under the thin top as possible. Not given: the motor, the magnet alloy.

المواد لهذه الخطوة:

محرك كهربائي1 قطعة

معدن غير معروف1 bands and arms

مغناطيس حِذوة1 قطعة

الأدوات المطلوبة:

طقم مفكات

Wire the speed control

Lead the motor wires out of the box through a regulating rheostat and a switch to a cord with a plug. The rheostat sets the motor speed, and so the stirring speed.

المواد لهذه الخطوة:

مقاومة متغيرة (ريوستات)1 قطعة

مفتاح قلّاب1 قطعة

سلك مرن بقابس1 قطعة

الأدوات المطلوبة:

طقم مفكات

Make the stirring rod

Take a small round permanent magnet rod, shorter than the width of the flask's bottom, and seal it in a thin shell of an inert material (porcelain, glass, Bakelite or a suitable plastic) so it cannot affect the liquid. Where bare iron or steel would do no harm, the shell may be left off. Ours: a sealed glass tube for the shell.

المواد لهذه الخطوة:

طقم مغناطيسات قضيبية1 rod magnet

أنبوب زجاجي1 shell

الأدوات المطلوبة:

موقد بنزن

Stir

Stand a non-magnetic flask or beaker of the liquid on the box and drop in the rod. Switch on and set the speed: the rod follows the turning magnet and whips the liquid into a deep vortex. Set the rod off-centre and it both spins and travels round the bottom, stirring faster still. The vessel can be closed, since no shaft goes in.

الأدوات المطلوبة: