measure of the unknown material that might be causing 
these rays, in the sample under examination. 
By eliminating the weaker samples and concentrating 
her work and attention on those that manifested these 
rays in the greatest intensity, after thousands of these 
tests, and nearly three years of the most exacting effort, 
she found a material that was millions of times more intense 
in these rays than the Uranium in which Professor Becquerel 
had first, accidentally, detected them. 
She called this material, —Radium. 
For her years of work, self-sacrifice, and toil, with tons 
of ore, she had a few thousandths of a thimbleful of material. 
From this she was able, later, to obtain a pure white metal, 
which had an atomic weight of 226; which melted at 700 
degrees Centigrade and which when exposed to the air 
quickly lost its metallic form by combining with other 
materials in the atmosphere to form salts. This was the 
pure Radium element. 
With her Radium,—Madame Curie and her husband 
soon gave the scientific world the proof that Radium intro- 
duced a new conception into the fundamental problems 
of existence. 
She proved that every three quarters of an hour the 
heat from a gram, (a thimbleful) of Radium is sufficient 
to change a quantity of water equal in weight to the Radi- 
um, from freezing to boiling point. 
This was a fact that compelled and still holds the 
attention of the scientific world. 
This is the fact that makes Radium the most interesting 
and the most important material in the earth. 
Heat means energy, power, work. Heat and light may 
oe obtained in many ways, but it is a new thing to find it 
being given off by a substance, as it is by Radium, year in 
and year out, without any apparent intermission or dimin- 
ation and without the substance being in any way con- 
sumed or altered. 
Before noting how the rays from Radium contribute 
to the life of today and what the heat from Radium holds 
of promise for the future, let us review the record of the