LUBRICATION

271

Committee. Department of Science and

(London)).

The surface tensions of mineral and of oik an* :i* it ii in
different. These oils are however very differ* nt in < r.o IIL'
respect tȣz., that the fixed oils ail have an active .lu ^Lu
which, gives them a strong adhesion for metals, ho th.it *•
oil is not readity squeezed out from between two :n«»tj*
faces (£/. langmuir (1919), Harking (1920), Bin^iit*m •
Lord Hayleigh (1918) has shown that a Saver ol la')ri-

Fio. 86.—lEustration of the necessity for high in aa cl w to
have the best lubricating quality.
monomolecular thickness possesses truly
in reducing the friction between solid bodies of
the contamination probably serving to prevent the
together of the surfaces. According to
a film formed from paraffin oil can be readily by a
stream of running water from platinum, etc,, but a
f ornxed "by oleic acid cannot be thus removed.
To get a clearer idea of the action of a cutting we mill
follo-w tlie operation of an Armstrong parting tool in off
disks from a rod of soft steel 1% in. in diameter, a
a constant speed and feed and as lubricants a of
lard oil or of mineral oil of the same viscosity. 30
were made with lard oil and at the end there was no