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SCIENCE PROGRESS 



of constitution and stability in inorganic chemistry. Amongst 

 many other nitrogen-containing derivatives of gold obtained 

 by reaction between auric chloride or auric hydroxide and 

 ammonia or ammonium salts — compounds of unsettled or 

 indefinite composition — the author has obtained a well-defined 

 tetra-ammineauric nitrate, Au(NH 3 )4.(N0 3 )3. This compound 

 crystallises out in glistening needles from a weak suspension 

 of ammonium nitrate in saturated ammonium nitrate solution 

 containing a little auric chloride. The salt is decomposed on 

 heating, but is stable in solution and gives double salts with 

 potassium, sodium, and ammonium nitrates. With soluble 

 salts of other acids, double decomposition takes place and 

 precipitates are obtained where Au(NH 3 ) 4 functions as a 

 specific trivalent metallic radicle. Thus, indicating this new 

 radicle by R, are obtained such salts as the following : 



Phosphate , . RPO, . H 2 

 Oxalate nitrate . R . (COO) 2 . N0 3 



Perchlorate . . R . (C10 4 ) 3 

 Sulphate perchlorate R . SO, . CIO, . 2H 2 



Oxalate perchlorate R . (COO) 2 . CIO, 

 Iodate . . . R.(I0 4 ), 

 Sulphate nitrate . R.S0 4 .N0 3 .H,0 

 Chromate . . R 2 . (Cr0 4 ) 3 



Now these compounds afford another example of a 

 phenomenon which is to be found in other inorganic com- 

 pounds. The trivalent radicle Au is somewhat amphoteric 

 and has not strong enough basic characteristics to form stable 

 salts with the above series of acidic radicles. When, however, 

 its basic character is reinforced by the inclusion within the 

 complex of three molecules of a basic group — in this case 

 NH 3 — it becomes capable of forming stable salts with the 

 stronger acidic groups, or in some cases with relatively weak 

 acidic groups, especially if these latter are assisted by the 

 presence of a strongly acidic group, as in the case of the 

 oxalate nitrate. 



ORGANIC CHEMISTRY. By P. Haas, D.Sc, Ph.D., St. Mary's 

 Hospital Medical School. 



The proof of the equivalence of the four valencies of the carbon 

 atom which was originally furnished by Henry {Bull. Acad. 

 Roy. Belg. 1886, Classe des Sciences, 12, (in), 644, 1888, 15, 

 333 and 1906, 722) can no longer be regarded as rigid in view 

 of the possibilities of intramolecular rearrangement on the lines 

 of the so-called Walden inversion. Fischer and Brieger 



