PRETENDED NEW METAL; PALLADIUM. 131 



ing an attachment in our ralnds to preconceived ideas, which 

 have been admitted without inquiring whether from truth or , 



from convenience. We eafily correct our judgment as to 

 fafts; and the evidence of experiment is equally convincing 

 to all perfons. But theories, not admitting of mathematical 

 demonftration, and being but the interpretation of a feries of 

 facts, are the creatures of opinion, and are governed by the 

 various impreflions made upon every individual. Nature 

 laughs at our fpeculations ; and though from time to time we 

 receive fuch warnings as (hould awaken us to a due fenfe of 

 our limited knowledge, we are prefented with an ample com- 

 penfation, in the exteniion of our views, and a nearer ap- 

 proach to immutable truth. 



The affinities of metals for each other are likely to be of the The affinity of 

 moft extenfi ve inifluence in chemiftry. They will promote fcep- ©ther, fo ftrongly 

 ticifm with regard to future difcoveries, and throw fome doubts Acwn in the 

 upon our prefent knowledge. Palladium is certainly not lefs J[L^f„duce * 

 different from the elements that corapofe it, and from all other doubts to the 

 metals, thap any two can be from each other. Within the laft "f^ meta?*"^ 

 fifteen or twenty years, feveral new metals and new earths have 

 been made known to the world. The names that fupport thefe 

 difcoveries are refpe6table, and the experiments decifive. If we 

 do not give our aflent to them, no (ingle propofition in che- 

 miftry can for a moment (land. But, whether all thefe are really 

 fimple fubftances, or compounds not yet rcfolved into their 

 elements, is what the authors themfelves cannot pofitively af- 

 fert; nor wquld it in the lead diminifh the merit of their 

 obfervations, if future experiments fliould prove them to have 

 been miftaken, as to the fimplicity of thofe fubftances. This 

 remark (liould not be confined to later difcoveries ; it ipay as; 

 juflly be applied to thofe earths and metals with which we have 

 been long acquainted. 



With regard to the melals, we have feen how little depend- Bilttle metals 

 ance is to be placed on fpecific gravities. A contrary anomaly ft^f more fu»- 

 to that which operates upon platina and mercury, jmay take pUfied. 

 place in others ; af)d they may become as much heavier than 

 the mean, as the former become lighter. In this flate of union, 

 they may for a long time appear homogeneous, even by the 

 teft of chemical re-agents. One of the properties that renders 

 pietallic fubflances fo precious is, their eafy formation into fuch 

 inftruments as our necefhties require. The fragile metals are 

 but of fecondary confequepce; and, at molt, ferve to conf 



