THE RARE EARTHS.—MAGEE. Ixxvil 
be filled in. Whence? Undoubtedly in most cases from the rare earths. 
Ni. and Co. according to Kriiss’ work seem to conceal an element which 
may be found to have an atomic weight of about 100 and the earths 
conceal many. Within a few years Di, has been split up, one component 
showing absorption bands and the other failing to do so, As already 
pointed out, two earths once considered simple have yielded at least 
twelve and when the means of the separation, when the reagent or 
method is finally found, then the vacant spaces will be filled. 
But it is not only that the rare earths will probably fill these vacant 
spaces in the table that gives them importance, their similarity is such 
in regard to action towards reagents that they seem to run contrary to 
the law. If so many of them are of the formula R,. O3, they cannot be 
distributed over the table but will mass in groups and destroy the table. 
Of course if the table is incorrect the sooner it is proven the better so 
that the mind of the inorganic chemist may be directed elsewhere for 
comparisons, and it is just possible that in this very thing lies the 
importance. Still the periodic law seems to rest on good foundation. 
The great importance then seems tu lie just here. These rare earths 
exist, of this there can be no doubt. The best chemical skill that the 
world has possessed have been working upon them for over a century, 
and have so far been unable to confidently state their number and 
actual properties. The more work that is put upon them the greater the 
number of them seems to be. If the ones now claimed are all real there 
is not room for them in the law, 7.e. spaces are wanting for their apparent 
weight. Until this question can be settled a mystery hangs over this 
portion of the Periodic system. The unravelling of this may work an 
entire change in our ideas of the elements. Their subtle resemblances 
have suggested to me more than once, while pondering over them, that 
in these lies the key to the simple elements which many chemists 
believe to be the foundation of the so-called elements. Ags in the 
Marsh-gas series the time comes when the Hydrogen-Carbon chain 
becomes too heavy for the bonds or affinity to sustain the weight, so in 
our inorganic field something of the same kind may result. The 
hypothetical elements may in certain numbers of atoms or in certain 
arrangement of atoms yield such similar properties that the one compound 
is distinguishable with difficulty from another. Time and high chemical 
skill alone can unravel the mystery, but so long as things remain as they 
are there remains an element of uncertainty in the periodic law. We have 
Proc. & TRANS. N. S. Inst. Sci., Vou. X. Proc.—H. 
