g. = 144.3/(144.3-degrees Baum?.)
or putting the rule in words, subtract the degrees Baum? from 144.3, and
divide 144.3 with the number thus obtained. For example: 32° Baum?
equals a sp. g. of 1.285.
144.3/(144.3-32) = 144.3/(112.3) = 1.285
This rule is for liquids heavier than water; for the lighter liquids the
rule is as follows:--
Sp. g. = 146/(136 + degrees Baum?.)
or in words divide 146 by the number of degrees Baum? added to 136. For
example: ammonia of 30° Beaum? has a sp. g. of 0.880 (nearly).
146/(136+30) = 146/166 = 0.8795
A simple series of calculations enables one to convert a Beaum?
hydrometer into one showing the actual sp. g. Graduation, according to
sp. g. is the most convenient for general purposes. In these instruments
the distances between the divisions become less as the densities
increase.
Twaddell's hydrometer is graduated in this way: Each degree Twaddell is
0.005 in excess of unity. To convert into sp. g. multiply the degrees
Twaddell by 0.005, and add 1. For example: 25° Twaddell equals a sp. g.
of 1.125.
25?.005 = 0.125; + 1.000 = 1.125.
There is a practice which ignores the decimal point and speaks of a sp.
g. of 1125 instead of 1.125. In some cases it is convenient, and
inasmuch as no substance has a real sp. g. of much over 20, it can lead
to no confusion.
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