174 On a new Metal, found in crude Plattna. 



(G 7.) In the formation of triple salts with the alkalis, 

 as observed by Mr. Chenevix, palladium may be said to 

 resemble platina; but the salts thus formed are far more 

 soluble than the corresponding salts of pbtina, and differ 

 entirelv in the colour and form of the crystals. 



(G 8.) The soda-muriate of palladium is a deliquescent 

 salt; that of platina, on the contrary, forms permanent 

 crystals. 



(G 9.) The triple salts of platina, with either muriate of 

 ammonia or of potash, form octacdral crystals of a yellow 

 colour, that are very sparingly soluble in water. The 

 corresponding salts of palladium likewise resemble each 

 other in every respect. The crystals are very soluble in 

 water, but insoluble in alcohol ; their form is that of a four- 

 sided prism, and they each present a curious contrast of 

 colour, that certainly is not observable in any known salt of 

 platina. 



(G 10.) Although the solution is of a deep red, the 

 cr\'stals are of a bright green when viewed transversely. 

 In the direction of their axes, however, the colour is the 

 same as that of the solution; but, on account of its extreme 

 intensity, it is with difficulty distinguished in fragments that 

 exceed — J-j- of an inch in thickness. One consequence of 

 tliis colour is nevertheless very observable; namely, that in 

 viewing any .crvstal obliquely, it appears of a dull brown, 

 that arises from a mixture of the red and green*. 



The characters of palladium that have been enumerated, 

 undoubtedly belong to none of the simple substances that 

 we are acquainted with; and no experiment that I have 

 made has tended to confirm the suspicion of its being a 



^ The change of colour above described, though certainly nncommoH, 

 is ncverihckis not pecu'iar to the s;ilts of palladium, hut may be seen also 

 in somekindiof tourmalin. Among those which comt lo us from Ceylon, 

 some arc transparent; and one varittv is of a deep red in the direction of 

 its axis, but of a yellowish green when viewed transversely. There i>, 

 also a corresponding, but opposite contrast of colours, that has bten ob- 

 served by \3iil!er, and described by Hergniann, in some of the Tyrolcse 

 tourmalins. The general aspect of these stones is black, and apparently 

 Op 'que. Seine, however, cf which the fiacture is vitreous, are found to 

 transmit a yellowish-red lightwhen viewed trans vewely, but in the direc- 

 tion of their axis the colour is a dull bottle-green. 



In each of these tourmahns, as well as in the salts of palladium, the 

 colour in the direction of the axis, is at le^st lo timts more intense tha-. in 

 the transverse direction. A tliin lamina, cut from the end of a Tyrolese 

 tourmalin for this purpoce, transniiited uo visible light, till it was reduced 

 toi-6othofan inch in thickness; and, when less than t-ioorhof an inch, 

 it was not more transparent than another portica of the same crystal seen 

 ttdjibvcrscly, i-icth of an inch in thickness. 



compound. 



