THE RARE EARTHS.—MAGHEE. lex 
limits for their size and weight, while Mendelejeff and Meyer have 
propounded a theory of classification. The subtle points will yet be 
chained and their properties scrutinized. 
For a long time, ever since chemistry became a science in fact, the 
need of a proper method of classification has been felt. There was no 
order, no opportunity therefore to apply mathematics, there was no compre- 
hensive and easy means of grasping the subject, each element and almost 
every compound must be studied by itself. So greatly was the need 
felt that, whenever a new property common to a few or several elements 
was noticed, attempts were made to make it the basis of a classification. 
Berzelius thought he had discovered a method but this was soon found 
wanting, not being founded on sufficient data ; when Faraday discovered 
the relations of the elements to the poles of the electric battery it was sup- 
posed to be settled, but this soon showed itself as a common property for 
all, extending from one end of the list of elements to the other and giving 
no special point where it could be said one class ended and another 
began, it soon resolved itself into the older metals and non-metals, 
hasigens and acidigens and so failed,—it was founded on the too narrow 
basis of a single property. Inklings of the truth were, however, 
obtaired from time to time. Dobereiner seems to have made the first 
suggestion which has led to the present system. He classified many of 
the elements into triads, taking as a basis a property certainly common 
to all, viz,—weight. He first noted that in many cases the weight of one 
element was the mean of that of two others usually resembling it, secondly, 
in other cases three elements with very similar properties possess very 
nearly equal atomic weights, viz,—Li., Na., K., and S., Se., Te., for 
examples of the first and Fe., Co., Ni., and RL, Rh., Pd., as examples of 
the second. The comparisons were continued by Pettenkofer, Dumas 
and others, clearer and still clearer signs of universal order appearing 
as the atomic weights were more and more accurately calculated. 
Newlands was able between 1860 and 1866 to arrange the elements in 
octads, but the gaps were so many and the table so fragmentary, and 
moreover so many elements were forced to stand aside that his friends 
jocularly suggested that he try arranging the elements according to the 
first letters of their names. Had Newlands possessed the full courage 
of his convictions England would have received the credit of the greatest 
advance in Chemistry since Liebig and WOhler founded Organic Chemis- 
try. It was left, however, for bolder minds. Lothar Meyer, and 
