File:The panorama of science and art (1823) (14597419439).jpg

Identifier: panoramaofscienc02smit (find matches)
Title: The panorama of science and art
Year: 1823 (1820s)
Authors: Smith, James, 1759-1828?
Subjects: Technology Technology
Publisher: London : Caxton Press
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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take fire. Tiiis mode oftrial is, however, rather ambiguous, though not quite so mnchso as. the mode of proving spirit by the size of the bubbles oaits surface, after shaking it up. The hydrometer constructed as above, cannot have a veryextensive range ; for if the stem be made heavy, small differ-ences in density will be detected with great difliculty, and ifit be long, it will be at the expense of portability. Anotherdefect arises out of its equal divisions; for the density ofspirit is not always in direct proportion to its purity; thus,if from twenty to thirty parts of spirit are mi.\ed with fromseventy to eighty of water, the two fluids combine moreintimately and occupy less space than in other proportions.To increase the range of the hydrometer, it has been pro- 1)osed to change the ballast or weight in the secondary ball,jut the improvement of Fahrenheit is the most to be ap-proved. Fahrenheits hydrometer, like the common one. HYI)))R>0§TATI(CS ASTD HinDUAUTILI rS , PLATE I.
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PuhU-rheii h\ Remj. Fixher. Caxtcn.LiverpoolJ821 HYDROMATICS AND HYDRAULICS. 89 Hydrostatics. Fahrenheits hydrometer. consists of a hollow ball, with a counterpoise below, but thestem above is very slender, and terminates in a small dish.Round the middle of the stem is made a mark, which ismerely a fine line. There are no divisions on the stem,which is always immersed in the fluid to be tried, up to themark, by placing as much weight as may be required in thelittle dish at the top. Hence, as the part immersed is con-stantly of the same magnitude, and the whole weight of thehydrometer is known; this last weight, added to the weightin the dish, will be equal to the weight of fluid displaced bythe instrument; and the specific gravity will be obtained bythis rule: as the whole weight of the hydrometer and itsload, when adjusted in distilled water, is to 1.000, so is thewhole weight, when adjusted in any other fluid, to a fourthproportional, which is the specific gravity to be ascertained.

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