Stibio- and Arsenio-Sulpkurets. 283 



the double salt. The double salt of barytes cannot be ob- 

 tained by precipitating a solution of cyanide of zinc-potassium 

 with acetate of barytes. It gives a white precipitate, insolu- 

 ble, or nearly so, which contains barytes, with evolution of 

 a strong smell of prussic acid. A corresponding combination 

 with oxide of lead was obtained on precipitating cyanide of 

 zinc-potassium with acetate of lead. It forms a white powder. 

 Acetic acid removes the lead, leaving cyanide of zinc behind. 



The compound was not analysed, but regarded as Zn Cy + Pb. 



This kind of combination of a cyanide with an oxide of another 

 metal will be new and remarkable, should it be confirmed. Cya- 

 nide of zinc-magnesium could not be prepared ; the cyanogen 

 is decomposed during evaporation, and a brown substance is 

 deposited. — (Bet's. Jahresber. vol. xx. part ii. p. 153.) 



On the Stibio- and Arsenio-Sulphurets. 



Persulphuret of antimony, Sb 2 S 5 , combines with basic sul- 

 phurets to form very peculiar crystallizable salts, of which, how- 

 ever, only the sodium and potassium compounds have been ex- 

 amined. Dr. Rammelsberg has published a memoir on the 

 subject. Some chemists consider Sb 2 S 6 as a mixture of 

 Sb 2 S 3 + S 2 , because it is decomposed into these elements by 

 boiling with oil of turpentine; its power, however, of form- 

 ing characteristic salts, speaks for its being a determinate 

 compound. [A fact in favour of its being a determinate sul- 

 phuret is, that when boiled with caustic soda, stibio-persul- 

 phuret of sodium and antimoniate of soda are formed, but no 

 hyposulphite ; on the other hand, the two atoms of sulphur 

 may be driven out at a temperature by which sulphur boils; 

 they may also be extracted by sulphuret of carbon.] (Mit- 

 scherlich, PoggendorjJTs Annalen, xlix. p. 412.) 



The stibio-persulphurets may be formed in several ways. 

 Those with the bases of the alkaline and earthy metals are 

 soluble in water, and are either colourless or yellow ; the in- 

 soluble salts are of various colours. The soluble sulphurets 

 are decomposed by carbonic acid; the insoluble ones are 

 often very difficult of decomposition. 



The stibio- persulphuret of potassium is deliquescent; its for- 

 mula is 3 K S + Sb 2 S 5 4- 9 H 2 O, or K 3 Sb + 9 H. When 



sulphuretted hydrogen is passed through a solution of the 

 neutral antimoniate of potash, persulphuret of antimony is 

 thrown down, and the above-mentioned stibio-sulphuret re- 

 mains in solution. Persulphuret of antimony loses its colour 

 when treated with a solution of caustic potash ; it dissolves, 



