4 An Account of some "Experiments on the 



cording to the quantity of silver employed ; and yet the 

 gold seems to be a necessary component for the perfect so- 

 lution ; for by mixing the following proportions of siluer 

 and platina, the results were thus : 



Platina and silver equal to 1 per cent, of the former left 

 in dilute acid a light powder partly subsiding. 5 per cent, 

 gave the acid a straw colour, half the platina employed 

 beinc dissolved. 10 per cent, a very bright straw colour, 

 havini: dissolved the same proportion. 



]5 per cent, a bright liuht brown, having dissolved ^-ths 

 of the platina. 25 per cent, a deep brown, dissolving -|-ds 

 of the platina. 



The two latter proportions required concentrated acid 

 after the action of the dilute. 



Maiden Lane, Wood Street, PeKCIVAL JohnsON, 



July 1, 1812. Assayer of Metals. 



It may also be worthy the notice of your readers, that we 

 find palladium to be such a general alloy of Brazil gold as 

 often to alter the cobur thereof. We have particularly ob- 

 served it in the Brazil coin, manv of which wtre rejected 

 at first sight, suspecting them to be counterfeits. VVe found 

 it a short time since in a Brazil bar to the amount of nearly 

 20 per cent, altering tlie colour thereof to nea.Iy that of 

 the metal palladium. 



J. AND P.J. 



II. A?i Jccoinil of some Erpohneiifs on the Comhinat'tont 

 of different Metals and Clilnrinf, ^c. By .John Daw, 

 Esq. Communicated by Sir liuMPHRV J)Avy, Knt. 

 LL.D. Sec.R.S.* 



Introduction. 



JVlv brother, .Sir ^lumphry Davy, appears to me to have 

 demonstrated, in his last Bakerian Lecture, the existence 

 of a class of bodies similar to metalhc oxides, and consist- 

 ing i>f metals ir union with chlorine or oxymuriatic acid. 



These combinations are the principal subject of the fol- 

 lowing pages. I shall do mvself the honour of giving an 

 account ot the experiments 1 have made to ascertain the 

 propf)rtions of their constituent parts, and likewise of de- 

 scribing some that have not yet been noticed. 



I shall have to relate also the attempts I have made to 

 ascertain the proportions of sulphur in several sulphuret«, 

 and the experiments I have performed to estimate the quan- 



• From Philosophical Transaction! for 1812, part i. 



tily 



