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34

Rule of ye Equilibrium of defferent Liquors by their weight.

We consider in this place two sortes of ye weight of bodies, one wch proceeds from ye mass of ye body, as a cubic foot of wood weighs more than a cubic inch of ye same matter, ye other proceeds from ye density of ye matter, or from some other cause by wch a body weighs more than another of an equal bulk, as a cubic inch of gold weighs more than a cubic inch of iron, we call ye last weight ye specific gravity, so specific gravity or weight of water is greater than that of oyl; we do not consider here ye weight of ye air in which ye body is weighed, although in strictness it ought to be considered.

[[image: drawing of a "U" shaped tube A (upper left opening), B (lower left corner), B (lower rightcorner), C (upper right opening).  There are dotted lines down side A B as follows: G, I,D E over to C B, L K over to C B, and H F over to C B.]]

In ye syphon A B C let there be an equilibrium of water to ye height D E, then pour gently oyl into ye branch C B untill it is at ye height C, it shall happen that ye water will descend below E, and be elevated above D in ye other branch;  let ye descent be E F, and D G ye elevation, and draw ye horizontal line F H then ye oyl F C shall be to ye water H G reciprocall as the specific weight of ye water is to that of  ye oyl;  for ye water F B shall make an equilibrium with ye water B H, therefore ye oyl F C shall make an equilibrium with ye water H G, now it is necessary to make ye whole remain in that estate that ye parts H and F should be equally pressed according to ye principall above:  therefore ye quantity of oyl F C shall weigh as much upon F as ye water H G upon H ye same thing happens to mercury and water;  for if we put in ye ^[[?H] syphon A B C mercury to ye height D E and pour gently water thrô C inclining ye syphon [[strikethrough]] A B C mercury [[/strikethrough]] a little at ye beginning to ye end that the water may not mix with ye mercury, and that ye water may be elevated unto C and ye mercury unto I, ye water will descend to ye horizontal line K L;  and then ye water K C with ye mercury K B, shall make an equilibrium with ye mercury B I;  and as ye specific gravity of ye mercury is to that of ye water, so reciprocally ye height L I and by that means it will be easy to determine the specific weight of liquors in reguard one of another, for if ye mercury be 14 times as heavy as water, K C shall be 14 times as great as L I.

Having considered ye equilibrium of liquors one with another we may consider that of firm bodys wch swim upon ye water, as wood, wax &c see ye rules 

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