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mercury be present* the excess is acted upon as in the case of mer- 

 cury, the liquor assuming a darker colour than with platina alone. 



From the above experiments, Mr. Chenevix infers that mercury 

 can act upon platina, and confer upon it the property of being pre- 

 cipitated, in a metallic state, by green sulphate of iron. The first 

 and second experiments prove, he says, that platina can protect mer- 

 cury from the action of nitric acid ; and also that mercury increases 

 the action of nitro-muriatic acid upon platina. The third, fourth, 

 fifth, sixth, seventh, and eighth experiments show that mercury can 

 combine with platina, in such a manner as not to be separated from 

 it by the degree of heat necessary to fuse the compound. The eighth 

 experiment proves that the action of mercury upon platina is not 

 confined to the metallic state, but that these metals can combine and 

 form an insoluble triple salt, with an acid that produces a very so- 

 luble compound with platina alone. The ninth experiment shows 

 that platina can retain in solution a certain quantity of mercury, and 

 prevent its detection by a substance which acts powerfully when pla- 

 tina is not present. 



Mr. Chenevix admits that one or two of the above-mentioned ex- 

 periments appear to contradict some of those he described in his 

 former paper on Palladium ; for in the present experiments, "platina 

 protects mercury against the action of nitric acid, whereas in pal- 

 ladium the mercury is not only acted upon itself, but contributes to 

 the solution of platina in the same acid." The discussion of these 

 objections, Mr. Chenevix says, he shall defer to another opportunity. 

 He also acknowledges that there is some incorrectness in his former 

 paper, with respect to the proportional quantities of the ingredients 

 that enter into the composition of the metallic precipitate formed by 

 means of green sulphate of iron ; and after making various remarks 

 on that head, states the mean result to be about 17 parts of mercury, 

 and 83 of platina, when the specific gravity of the compound was 

 about 16. 



Mr. Chenevix concludes by observing, " that he has as yet seen 

 no arguments of sufficient weight to convince him, in opposition to 

 experiment, that palladium is a simple substance. Nothing is more 

 probable, he says, than that nature may form the alloy called palla- 

 dium, and even form it better than we can do ; and he thinks that 

 the amalgamation to which platina is submitted before it reaches 

 Europe, is sufficient to account for its containing a small portion of 

 palladium." With respect to the failure that has happened in the 

 attempts of others to make palladium, he says he is himself too well 

 " accustomed to such failure not to believe that it will happen, even 

 in well conducted trials ;" but he considers four successful experi- 

 ments, which were not performed in secret, as a sufficient answer to 

 that objection. 



The experiments above related tend, in his opinion, to confirm his 

 former results ; but he allows that he can prescribe no other means 

 for success than perseverance ; and as Messrs. Fourcroy, Vauquelin, 

 N 2 



