Home Index Site Map Up: Glassmaking Navigation
Up: Glassmaking

First: Gilbert · Glass Blowing · Cover Last: Gilbert · Glass Blowing · Page 62 Prev: Gilbert · Glass Blowing · Page 10 Next: Gilbert · Glass Blowing · Page 12 Navigation
Gilbert: 14 of 65
·Cover ·Page 20 ·Page 42
·Page i ·Page 21 ·Page 43
·Page ii ·Page 22 ·Page 44
·Page 1 ·Page 23 ·Page 45
·Page 2 ·Page 24 ·Page 46
·Page 3 ·Page 25 ·Page 47
·Page 4 ·Page 26 ·Page 48
·Page 5 ·Page 27 ·Page 49
·Page 6 ·Page 28 ·Page 50
·Page 7 ·Page 29 ·Page 51
·Page 8 ·Page 30 ·Page 52
·Page 9 ·Page 31 ·Page 53
·Page 10 ·Page 32 ·Page 54
·Page 11 ·Page 33 ·Page 55
·Page 12 ·Page 34 ·Page 56
·Page 13 ·Page 35 ·Page 57
·Page 14 ·Page 36 ·Page 58
·Page 15 ·Page 37 ·Page 59
·Page 16 ·Page 38 ·Page 60
·Page 17 ·Page 39 ·Page 61
·Page 18 ·Page 40 ·Page 62
·Page 19 ·Page 41


    Now look at the water level in each of the tubes. Is it above the level of the water in the glass, and is it higher the smaller the inside diameter of the tube, that is, is it higher in the No. 2 than in the No. 4, and in the No. 4. than in the No. 6?
    Now take the thin capillary tube which has the largest inside diameter, place one end in the glass of water, suck it full of water and blow it out. Now with one end in the glass of water notice quickly how the water rises inside the tube. Does it run uphill in a most magical manner (Fig. 20), and does it remain there?
Water Runs Up Tube
FIG. 20
    Repeat this with your other capillary tubes. Does the water run uphill in each, and does it rise higher the smaller the inside diameter of the tube?
    The "why" of this is explained in Gilbert's "Experimental Mechanics" under "Capillarity."
    Common glass is made from three substances with which you are all more or less familiar; namely, sand, sodium carbonate (washing soda), and lime.
    If sand and soda or potash are mixed and heated to a high temperature, they will melt together and produce a glass which dissolves in water. This is known as "water glass" and it is used in many ways: to preserve eggs, to cement fire bricks, to make fireproof cement, and so on. If, however, lime is added and the mixture is heated to a high temperature, a glass is produced which is not soluble in water. This is the glass you know.
    The three more common kinds of glass are: Venetian glass, made from sand, soda, and lime; Bohemian glass, from sand,