THE CHEMICAL ELEMENTS—RAMSAY. 191 
energy at the same rate that gun-cotton does, we should have an 
undreamed-of explosive; could we control the rate we should have a 
useful and potent source of energy, provided always that a sufficient 
supply of radium were forthcoming. But the supply is certainly a 
very limited one; and it can be safely affirmed that the production 
will never surpass half an ounce a year. If, however, the elements 
which we have been used to consider as permanent are capable of 
changing with evolution of energy; if some form of catalyser could be 
discovered which would usefully increase their almost inconceivably 
slow rate of change, then it is not too much to say that the whole 
future of our race would be altered. 
The whole progress of the human race has indeed been due to 
individual members discovering means of concentrating energy, and 
of transforming one form into another. The carnivorous animals 
strike with their paws and crush with their teeth; the first man who 
aided his arm with a stick in striking a blow discovered how to con- 
centrate his small supply of kinetic energy; the first man who used a 
spear found that its sharp point in motion represented a still more 
concentrated form; the arrow was a further advance, for the spear 
was then propelled by mechanical means; the bolt of the crossbow, 
the bullet shot forth by compressed hot gas, first derived from black 
powder, later, from high explosives; all these represent progress. To 
take another sequence: The preparation of oxygen by Priestley 
applied energy to oxide of mercury in the form of heat;.Davy im- 
proved on this when he concentrated electrical energy into the tip of 
a thin wire by aid of a powerful battery, and isolated potassium and 
sodium. 
Great progress has been made during the past century in effecting 
the conversion of one form of energy into others, with as little useless 
expenditure as possible. Let me illustrate by examples: A good 
steam engine converts about one-eighth of the potential energy of the 
fuel into useful work; seven-eighths are lost as unused heat and useless 
friction. A good gas engine utilizes more than one-third of the total 
energy in the gaseous fuel; two-thirds are uneconomically expended. 
This is a universal proposition; in order to effect the conversion from 
one form of energy into another, some energy must be expended 
uneconomically. If A is the total energy which it is required to con- 
vert; if B is the energy into which it is desired to convert A; then a 
certain amount of energy, C, must be expended to effect the conver- 
sion. In short, A=B+C. It is eminently desirable to keep C, the 
useless expenditure, as small as possible; it can never equal zero, but 
it can be made small. The ratio of C to B (the economic coefficient) 
should therefore be as large as is attainable. 
The middle of the nineteenth century will always be noted as the 
beginning of the golden age of science; the epoch when great generali- 
