Il6 ABSOLUTE ATOMIC WEIGHT. 



in qualitative analysis for the detection of these metals and 

 has been found to extend to compound radicals and even 

 alkaloids. 



The most decisive and elegant method of applying these 

 tests in microchemistry is based upon the wonderful crys- 

 tallizing tendency of these so-called double salts. 



The common microchemical test for potassium or ammo- 

 nium by means of the platinic chloride has all the charac- 

 ters of a first class test: Sensitive, decisive and beautiful. 



The great value of these reactions was already recognized 

 by Berzelius for atomic weight determinations. In one 

 experiment he used nearly 3 grammes of platinum and 

 obtained an analytical ratio exact to the third decimal. 



This reaction has been very skillfully used by Karl 

 Seubert for the determination of the atomic weight of 

 platinum. 



I take great satisfaction in being able to put the name 

 of Karl Seubert at the head of this section, as that of a 

 modern Chemist who has done chemical work truly in the 

 spirit and according to the methods of Berzelius in so 

 excellent a manner that I doubt not, his name will remain 

 connected with the atomic weight of this most remarkable 

 modern metal. 



In the future we trust there will be less determinations 

 and much better ones than have been produced since Stas 

 demoralized chemistry and Lothar Meyer re-calculated 

 atomic weights. 



I contend that the name of the analyst at the head of each 

 atomic weight will remain there, as surely as that of the 

 founder of a new genus in botany. 



Seubert has produced the first positive determinations 

 permitting the establishment of the true and absolute atomic 

 weight of platinum. That fact cannot be changed. Hence 

 that name must stay. 



These so-called double chlorides are really chloro-terna- 

 ries; see our general formulae, also in the " Statistik der 

 Krystall Symmetric " presented by Haidinger to the Acad- 

 emy of Sciences of Vienna, Sitzungsberichte, I Abth. Bd. 

 62,1870 Typus, Tetrate ; IV. Chloro-salze. 



