REPOET OF THE SECRETARY. 29 



from 1837 to 1845. The observations of Lieutenant Grilliss were pub- 

 lished by order of the Senate of the United States ; but have not 

 been discussed in reference to the various influences to which the 

 needle is subjected. Those of Professor Bond are still in manuscript, 

 but will probably be published in due time, as a part of the labors of 

 the Harvard observatory. 



The fact was mentioned in the last report, that a small appropriation 

 had been made, to assist in defraying the expense of the necessary 

 material and apparatus for an investigation undertaken by Professor 

 Wolcott Gribbs relative to the ores of iDlatinum, of which the following 

 is an account : 



Samples of the ores of platinum, according to Gmelin, were first 

 brought to Europe in the year 1741. In 1748, the metal was described 

 by Don Antonio de Ulloa as a metallic stone, which, when present in 

 large quantity, prevents the working of the gold ores. Watson recog- 

 nized platinum as a distinct metal in 1750, and after that period very 

 numerous investigations were published in regard to it. In 1804, 

 Wollaston announced the discovery of palladium and rhodium in the 

 raw platinum ores, and shortly afterward Smithson Tennant showed 

 that the same ore contained two other metals, which he called iridium 

 and osmium. Finally, in 1844, Claus discovered ruthenium. The 

 investigation of the metals accompanying platinum has always been 

 regarded as one of peculiar difficulty, in consequence of the remarkable 

 analogies between the chemical properties of the metals themselves. 

 The comparatively recent discovery of ruthenium illustrates this point 

 in a striking manner. All previous investigations related chiefly to 

 mixtures of the metals in various proportions, hardly a single one 

 having been obtained in a state of purity. Claus's most elaborate and 

 successful investigation threw a new light on the whole subject, with- 

 out, however, removing all the difficulties which accompany a complete 

 separation of the different metals. In 1859, Deville and Debray pub- 

 lished a detailed memoir on the working of the ores^of platinum upon 

 a large scale, and on the physical properties of fhe different metals. 

 In this very valuable paper, methods of fusing large quantities of 

 platinum are given, the processes employed being, however, essen- 

 tially the same as those successfully used in this country by Dr. Hare 

 many years since. 



The purely chemical question of the complete separation of the 

 different metals of the platinum group from each other, remained 

 unsolved. The investigations of Dr. Gibbs have been undertaken 

 partly to supply this deficiency, and partly in consequence of his dis- 



