THE PLATINUM METALS S97 



'ing thiocarbamide, CSN 2 H 4 , in the place of ammonia, PtCl 2 ,4CSN 2 H 4 , 

 and others corresponding with .Reisetfs salts. Hydroxylamine, and 

 other substances corresponding with ammonia, also give similar com- 

 pounds. The common properties and composition of such compounds 

 show their entire analogy to the cobaltia compounds (especially for 

 ruthenium and iridium) and correspond to the fact that both, the 

 platinum- metals, and cobalt occur in the same, eighth, group. 



molecules is naturally more developed in the Idwer forms of combination than in the 

 higher. Hence the salts of Reiset's first base for example, PtCl 2 ,2NH 3 ,2NH 3 both 

 combine with water and give precipitates (soluble in water but not in hydrochloric acid) 

 of double salts with many salts of the heavy metals for example, with lead chloride, 

 cupric chloride, and also with platinic and platinous chlorides* (Buckton's salts). The 

 latter compounds^ will have the composition PtCl 2? 2NH 3 ,2NH 3 ,PtCl 2 that is, the same 

 composition as the salts of Reiset's second base, but it cannot be identical with it. 

 Such an interesting case does actually exist. The first salt, PtCl 2 ,4NH 3) PtCl 2 , is green, 

 insoluble in water and in hydrochloric acid, and is known as Magnus's salt, and the 

 second, PtCl 2 ,2NH 3 , is Reiset's yellow, sparingly soluble (in water). They are polymeric, 

 namely, the first contains twice the number of elements held in the second, and at the 

 same time they easily pass into each other. If ammonia be added to a hot hydrochloric 

 acid solution of platinous chloride, it forms the salt PtCl 2 ,4NH 3 , but in the presence of 

 an excess of platinous chloride it gives Magnus's salt. On boiling the latter in ammonia it 

 gives a colourless soluble salt of Reiset's first base, PtCl 2 ',4NH 3 , and if this be boiled with 

 water, ammonia is disengaged, and a salt of Reiset's second tase, PtCl 2) 2NH 3 , is obtained. 

 A class of platino-ammonium isomerides (obtained by Millon and Thomsen) are also 

 known. Buckton's salts for example, the copper salt were obtained by them from the 

 salts of Reiset's first base, PtCl 2 ,4NH 3 , by treatment with $ solution of cupric chloride, 

 fec., and therefore, according to our method of expression, Buckton's copper salt will be 

 PtCl 2 ,4NH 3 ,CuCl 2 . This salt is soluble in water, but not in hydrochloric acid. In io 

 the ammonia must be considered as united to the platinum. But if cupric chloride be 

 dissolved in ammonia, and a solution of platinous chloride in ammonium chloride is 

 added to it, a violet precipitate is obtained, of the same composition as Buckton's 

 3alt, which, however, is insoluble in water, but soluble in hydrochloric acid. In this a 

 portion, if not all, of the ammonia must be regarded as N united to the copper, and it must 

 therefore be represented as CuCl 2 ,4NH 3 ,PtCl 2 . This form is identical in composition 

 but different in properties (is isomeric) with the preceding salt (Buckton's). The salt of 

 Magnus is intermediate between them, PtCl 2 ,4NH 3 ,PtCl.j ; it is insoluble in water. and 

 hydrochloric acid. These and certain other instances of isomeric compounds in the 

 series of the platino-ammQnium salts throw a light on the nature of the compounds in 

 question, just as the study of the isomerides of the carbon compounds has served and' 

 still serves as the chief cause of the rapid progress of organic chemistry. In conclusion, 

 we may add that (according to the law of substitution) we must necessarily expect all 

 kinds of intermediate compounds between the platino and analogous ammonia deriva- 

 tives on the one hand, and the complex compounds of nitrous acid on the other. 

 Perhaps the instance of the reaction of ammonia upon osmic anhydride, Os0 4 , observed 

 by Fritsche, Fr&tny, and others, and more fully- studied by Joly (1891), belongs to this 

 class. The latter showed that when ammonia acts upon an alkaline solution of OsO 4 

 the reaction proceeds according to the equation : OsO 4 + KHO + NH 3 = OsNK0 3 + 2H 2 O. 

 It might be imagined that in this case the ammonia is oxidised, probably forming the 

 residue of nitrous acid (NO), while the type OsO 4 is deoxidised into OsO 2 , and a salt, 

 OsO(NO)(KO), of the type 03X4 is formed. This salt crystallises well in light yellow 

 octahedra. It corresponds to osmiamic acid, OsO(ON)(HO), whose anhydride, 

 [OsO(NO)]o, has the composition Os 2 N 2 O 5 , which equals 2Os + N 2 O 5 to the same extent 

 as the above-mentioned compound PtC0 2 equals Pt + CO ? (see Note 11). 



