PROCEEDINGS. 



years since, on an unsuspected corner of the reagent shelf, an organic 

 compound a-nitroso /3-naphthol was found to instantly and completely 

 separate them from each other. Such being the case, we may some day 

 expect research to be rewarded and the mysterious doors to be opened. 



I must now, however, in the development of my plan, state the 

 methods most in vogue for separating any rare earth from a mixture off 

 them. Suppose we have a mixture of all or nearly all of these earths,, 

 and this is the state in which we usually get them from the minerals, 

 containing them, and that we have, say 5 litres, in solution. We remove- 

 lOc.c. and precipitate all the earths by means of a standard solution of 

 ammonia, noting carefully the exact amount required. From this can 

 readily b6 calculated the amount neceasary to precipitate the 5 litres. 

 This being determined we take enough of a somewhat weak solution of 

 ammonia to precipitate one-tenth of the earths and add it as rapidly as 

 possible, with violent agitation, that it may be brought in contact with 

 as large a portion of the solution as possible at once. This precipitates 

 the most basic portion to a large extent. The mixture is allowed to 

 settle and the supernatant liquid is drawn off; after which the precipi- 

 tate is carefully washed and the washings are added to the liquid. This 

 is again treated with ammonia, another tenth being thrown down. This 

 process is repeated till the entire amount is precipitated. The first two- 

 or three precipitates are then united, then the next two or three and so 

 on, and each group is again treated in a similar manner, till after some 

 hundreds of repetitions there collects at one end of the series a consider- 

 ably basic, and at the other a considerably acid, hydroxide. The various 

 precipitations are checked by atomic weight determinations, and when an 

 hydroxide is obtained in which the entire ten precipitates yield identi- 

 cally the same atomic weights, it is considered as an elemental earth,, 

 the argument being that no two elements will be at all likely to possess 

 the same basic qualities. This will probably give you an idea of the- 

 time expended and the difficulty experienced in working in this field..* 

 Ammonia is by no means the only reagent so employed, but every one 

 likely to produce different qualities of precipitates is tried. 



Here, then, we have a group of elements whose compounds act 

 differently toward chemical reagents from all other bodies. They 

 resemble the alkalies and alkaline earths, i. e., the Li. and Gl. families in 

 their action toward H 2 S, and the B. and Fe. families in their action 

 towards (NH 4 ) 2 S. They resemble the last two and all the other families 

 except the Li. and Gl. families in their action toward NH 4 OH. They 



