June 29, 1900.] 



SCIENCE, 



1017 



a false premise. There was something 

 almost prophetic in the observations of 

 Chenivix, for there are in chemistry no 

 elements whose properties exhibit such 

 great variability when not pure, as do 

 those of the platinum group. 



The still anonymous discoverer of palla- 

 dium immediately offered through Nichol- 

 son's Journal a reward of twenty pounds 

 sterling to any one who should manufacture 

 even twenty grains of real palladium,* and 

 many chemists entered into the discussion 

 as to the elementary character of the metal. 

 On June 24, 1804, three days after Tennant 

 had made known the discovery of iridium 

 and osmium, Wollaston read a paper be- 



preconceived ideas, which have been admitted with- 

 out inquiring whether from truth or from conveni- 

 ence. We can easily correct our judgment as to facts 

 and the evidence of experiment is equally convincing 

 to all persons. But theories, not admitting of mathe- 

 matical demonstration, and being but the interpreta- 

 tion of a series of facts, are the creatures of opinion, 

 and are governed by the various impressions made 

 upon every individual. Nature laughs at our specu- 

 lations ; and though from time to time we receive 

 such warnings as should awaken us to a due sense of 

 our limited knowledge, we are presented with an 

 ample compensation, in the extension of our views, 

 and a nearer approach to the immutable truth." 

 Phil. Trans. 93, 317 (1803). 



*"Dec. 19, 1803. Editor Nicholson's Journal. 

 Sir: As I see it said in one of your Journals that the 

 new metal I have called palladium is not a new noble 

 metal as I have said it is, but an imposition aud a 

 compound of platina and quicksilver, I hope you will 

 do me the justice in your next and tell your readers 

 I promise a reward of &20, now in Mrs. Foster's 

 hands, to any one that will make only 20 grains of 

 real palladium, before any three gentlemen chemists 

 you please to name, yourself one if you like. That 

 he may have plenty of his ingredients, let him use 20 

 times as much quicksilver, 20 times as much platina, 

 and in short of anything else he pleases to use ; neither 

 he nor I can make a single grain. Pray be careful in 

 trying what it is he makes, for the mistake must hap- 

 pen by not trying it rightly. My reason for not saying 

 where it was found was that I might make some ad- 

 vantage of it as I have a right to do. * * * I hope 

 a little bit of whatever is made may be left with Mrs. 

 Foster." Nich. J. 7, 75, 159 (1804). 



fore the Royal Society * acknowledging 

 himself to be the discoverer of palladium. 

 "Wollaston had been engaged in an effort to 

 obtain malleable platinum, and having pre- 

 cipitated his solution of the ore with iron, 

 he found a part of this precipitate to be 

 soluble in a mixture of hydrochloric acid 

 with saltpeter, potassium chlorpalladate 

 being formed. He at once concluded that 

 palladium must be a simple metal, because 

 there is ' no instance in chemistry of a dis- 

 tinctly crystallized salt containing more 

 than two bases combined with one acid,' 

 another correct conclusion drawn from a 

 false premise. In his solution Wollaston 

 found also indications of rose-colored solu- 

 ble crystals which he attributed to another 

 new metal, and to this he gave the name 

 rhodium. This is the explanation of his 

 curious method of making known his dis- 

 covery of palladium : " On this and on 

 other accounts I endeavor to reserve to my- 

 self a deliberate examination of these diffi- 

 culties, which the subsequent discovery of 

 a second new metal, that I have called 

 rhodium, has since enabled me to explain, 

 without being anticipated even by those 

 foreign chemists whose attraction has been 

 particularly directed to this pursuit."t It 

 is possible from this that Wollaston himself 

 had been led to his work in part at least 

 by the earlier observations of the French 

 chemists. J 



* Phil. Trans., 94, 419 (1804). 



t Nicholson's J., 10, 204 (1805). 



% Since this address was in type, I have received 

 the interesting Presidential Address of Dr. Thorpe to 

 the Chemical Society (London), in which this episode 

 is treated quite exhaustively. What WoUaston's 

 motive was in bringing his discovery to the notice of 

 the scientific world in so extraordinary a manner. 

 Dr. Thorpe says can only be surmised. Is not how- 

 ever, in view of WoUaston's statement, the motive 

 clearly apparent? He had found palladium ; he 

 was in pursuit of rhodium ; he knew that at least 

 four other distinguished chemists were also on track 

 of new metals in platinum residues, and any hint 

 such as the publication of his work on palladium 



