The exact chemical constituents have not as yet been accurately determined, simply because tung oil has never been found uniform, as will be seen from tables of the results of analyses by various authorities in chemistry. One authority, Cloez, asserts that tung oil is a mixture of 25 per cent of the glycerides of oleic acid and 75 per cent of margarolic acid, and says that the latter separates in crystals on adding an alcoholic solution, while the former remains in solution. The combination with lead oxide is only feasible after long heating of the oil, the lead soap melts at 212 degrees Fahrenheit, but the oil is easily saponifiable with an alcoholic solution of caustic soda. Another authority, Wenghoefer, as early as 1882 in his chemistry of hydro carbons, says that margarolic acid melts at 105 degrees Fahrenheit, and is a member of the group Cn H2N3 - CO.OH with the empirical formula C17H30O2. This acid forms by a change during the heating of over 392 degrees Fahrenheit and has a melting point of 160 degrees Fahrenheit.
Elaeolic acid may be had from elaeomargaric acid (margarolic acid) as well as from elaeostearic acid, when these are heated to about 350 degrees Fahrenheit under exclusion of air. It also forms, when the oil is extracted with carbon bisulphide and heated to 212 degrees Fahrenheit. The acid melts at 38 to 40 degrees Fahrenheit. As all the three acids may be present in mixture and also as glycerides, it stands to reason that the viscosity of the limpid oils, as well as the melting point of the gelatinized oils may be very different depending upon which of the acids is in preponderance. This would explain why tung oil from various shipments will give varying results in practice and shows how necessary it is to test each shipment.