LUBRICATION

275

Benzene (C6H6) represents a typical paraffin-base hydro-
carbon, diallyl (C6Hi0) may be taken to represent an unsaturated
non-cyclic hydrocarbon,, whereas benzene (C6Hg) and hexa-
methylene (C6H12) represent types of cyclic hydrocarbons. All
of these compounds have the same number of carbon atoms, but

10°

40° 50° 60° 10° 80°
Temperature, Centigrade

90° 100° 110°

Pro. 88. — A comparison, of the fluidity-temperature curves of hydrocarbons
of different homologous series.
whereas their fluidity-temperature curves are nearly parallel,
they are widely different as shown in Fig. 88, the fluidity of
tfaie cyclic compounds being extraordinarily low even at their
"boiling points, marked by large circles in the figure. The higher
engine in mid-air, due to the sudden, confining of the gas mixture within
tb.e cylinders of the engine. Flying parts of the engine resulting from such
an explosion may also injure the steering mechanism, the supporting planes,
or even the pilot.