mark. Well, since in your reading of methods and new
processes, you will often meet with specific gravity numbers and desire
to convert these into Twaddell degrees, I will give you a simple means
of doing this. Add cyphers so as to make into a number of four figures,
then strike out the unit and decimal point farthest to the left, and
divide the residue by 5, and you get the corresponding Twaddell degrees.
If you have Twaddell degrees, simply multiply by 5, and add 1000 to the
result, and you get the specific gravity as usually taken, with water as
the unit, or in this case as 1000. An instrument much used on the
Continent is the Beaume hydrometer. The degrees (_n_) indicated by this
instrument can be converted into specific gravity (_d_) by the
formula: _d_ = 144.3/(144.3 - n)
_Ebullition or Boiling of Water, Steam._--The atmosphere around us is
composed of a mixture of nitrogen and oxygen gases; not a compound of
these gases, as water is of hydrogen and oxygen, but a mixture more like
sand and water or smoke and air.
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