20 
NATURAL PHILOSOPHY SECTION. 
Two meetings have been held during the Session, when papers 
were read by Mr. Holt, B.Sc., and Mr. Hatch, M.Sc. The following 
is a summary of the papers :— 
The Chemistry of Oils and the Principles of Lubrication. 
By T. J. W. Hott, B.Sc. 
After defining the word “oils,” the Paper described how they might 
be classified according to their chemical composition. The ‘first class 
considered was that of the fatty oils, or combinations of fatty acids with 
higher alcohols, a class subdivided into waxes or esters, and glycerides. 
Stress was laid upon the effect of unsaturation upon the properties of the 
fatty oils. Saponification and hydrolysis of the resulting soaps were 
shown by experiments. The acids and anhydrides which compose resin, 
and the result of resin distillation were also described. 
The next class taken consisted of essential oils and turpentines, the 
constitution of terpenes, the most important constituents of many oils of 
this class being dealt with. 
The tar, or oils with benzene, naphthalene, anthracene, and their 
derivatives formed another class. 
The last class consisted of the hydro-carbon oils obtained by dis- 
tillation of shale, and those also which are taken direct from the earth. 
The methods of separation, purification, and the various products 
obtained from them were briefly described. 
During the consideration of lubricants and lubrication, the necessity 
of suitable oils for particular work and conditions was emphasised, and 
the great variation of viscosity with change of temperature was shown 
by charts; and the relative merits of fatty and hydro-carbon oils were 
discussed, 
The Age of the Earth. 
By Herpert Harcu, M.Sc. 
The chief methods of estimation are— 
(1) By considering the rate at which the Earth is cooling from 
its original molten condition. 
(2) From the rate of tidal retardation, which is gradually 
increasing the length of the day. 
(3) By finding the total thickness of the sedimentary strata, 
and the average rate at which such strata are being laid 
down. 
(4) By dividing the total amount of a certain salt present in 
the ocean by the amount of it which is brought down 
each year by all the rivers of the world. 
(5) Methods based on the rate at which elements are being 
formed by radio-activity. 
Calculations based on rates of cooling, such as the first, are now of 
little value, since the study of radium has proved that there are causes 
adding to the total amount of heat. The Earth may not be a cooling 
body. 
Purely geological methods are difficult, because of the numerous 
breaks in the succession (unconformabilities). Most deposits vary 
largely in thickness when traced from place to place. Also, as strata are 
being laid down at very different rates, it is difficult to strike an average, 
The fourth and fifth methods have given very consistent results, 
The best salt to consider is common salt. The amount present in most 
of the great rivers of the world has been found with accuracy, and we 
have an approximate knowledge of the total amount of water poured 
into the ocean per year, and of the volume of the ocean. Of course, we 
