Ixxiv PROCEEDINGS. 
weakly acid solution, or send a small sample to me when I would be 
pleased to report the presence or absence of the earths. If the suspected 
mineral contains Di. a direct vision spectroscope will detect it at once by 
simply looking through it at the mineral. Now, finally, to give a little 
attention to what, according to my heading, ought to be the most 
important part of my paper. Why are the rare earths of especial 
importance to the chemical world? Why did such a chemist as Kriiss 
give up so much of his too-soon ended life to their study? Why do 
Brauner, Nilson, Cleve, Boisbaudren, Debray, Crookes, and scores of 
lesser lights give all the time they can spare to solve the mystery? Why 
did Crookes, when a few pounds of Sipylite, so far a rare mineral, were 
found not long since in Texas, cable to reserve it all for himself at any 
price? Why did chemists like Marignac and Bunsen in the latter part 
of their life, with all their vast accumulations of scientific knowledge and 
their tried analytical skill, give their finest work to the unravelling of 
this problem? For two reasons chiefly. The desire to discover the 
truth, the aim of every true scientist, coupled with the knowledge that 
here was a field to test the mettle of the bravest and ablest, but also, 
and perhaps more important for proving the falsity of, or on the other 
hand, rounding out the periodic system of the elements. 
The scientist ever seeks to bring the subject which he studies under 
the power of mathematics. He recognizes that this is the most power- 
ful of instruments with which to work. All branches of science have, 
however, to pass the observational stage before laws can be deduced and 
classifications brought about. Though several chemical facts can be 
discussed mathematically, the subject as a whole is but emerging from the 
observational stage. Botany is still in this stage as also Bacteriology, the 
latter, of course, far behind the former ; and _ possibly it may be claimed 
that the former is nearer mathematical control than chemistry. Its 
classification is certainly superior, but its classification, at least the one 
now in use, is a superficial one and readily arrived at. Not so Chemistry. 
The atom and even the molecule, evades our grasp and laughs at our skill, 
the balance alone conquers them and even here we grasp them but 
lightly. Their existence, even, is being disputed so evasive are they, 
and those who would claim their existence are confronted by metaphysi- 
cal reasonings to prove them only hallucinations. It has been a long 
and weary search since Dalton propounded his atomic theory but the 
reward seems nearer. Thompson, or I should say Lord Kelvin, is fixing 
