Siphon Tube: Glass Tube Bent with Drawn-Down Ends (Faraday, 1830)

A glass siphon for drawing clear liquid off a settled deposit, which Michael Faraday (1830) rated far better than pouring. He bends a glass tube about 0.3 inch inside and 22 inches long so that one leg is about 2 inches longer than the other, and draws both ends down to about 0.2 inch. The narrow ends hold the liquid in while one end is closed with a finger; the wide body lets it run fast. Source: M. Faraday, Chemical Manipulation (1830), §550, pp. 241-242. Picture: his text and figure.

متوسط

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التعليمات

Read Faraday

"Let a piece of glass tube, about 0.3 of an inch internal diameter, 22 inches in length, and of sufficient thickness to bear ordinary laboratory work, be bent at the blow-pipe table, so that one limb shall be about two inches longer than the other; the extremities should be contracted at the lamp, until about 0.2 of an inch in diameter."

Cut the tube

Take glass tube about 0.3 in. inside diameter, thick enough for ordinary laboratory work, and cut 22 in. off it: make a deep mark round it with the edge of a sharp three-square file, then break it like a stick, pulling the hands slightly apart (§1152). Wall thickness in figures is not given (unknown).

المواد لهذه الخطوة:

أنبوب زجاجي1 22 in.

الأدوات المطلوبة:

مبارد (مبرد يدوي)

Bend it

Bend the tube in the flame of the blow-pipe table so that one leg is about 2 in. longer than the other. For so sharp a bend, do not bend it all at one spot: heat and bend one part as far as it will go without narrowing the bore, then heat the next part and carry the curve on until the legs are close (§1160).

الأدوات المطلوبة:

شعلة نفخ زجاج طاولية

Draw down the ends

Heat each end and pull it along its length so that it lengthens and narrows (§1166), until the opening is about 0.2 in. across.

الأدوات المطلوبة:

شعلة نفخ زجاج طاولية

Use it

Hold the siphon upside down with the short leg higher, fill it with water from Faraday's dropping-bottle (a wash bottle does the same job), holding its beak against the side of the opening so no air bubbles are caught; close the long leg with a finger and fill the short leg too. Turn it over, put the short leg into the liquid and lift the finger: the clear liquid runs out. A finger on the outer end slows or stops it; keep the inner end clear of the deposit (§§550-551).

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