OXINDOL. 389 



Oxindol, C 8 H 7 l!s&quot;0. Is formed by further reduction 

 of dioxindol with tin and hydrochloric acid or with 

 sodium-amalgam in a dilute solution, kept constantly 

 acid. Long, colorless needles or feathery groups. 

 Difficultly soluble in cold water, easily soluble in hot 

 water and in alcohol; fuses at 120 ; and in small quan 

 tities, it can be distilled without undergoing decom 

 position. When its aqueous solution is evaporated in 

 contact with air, it becomes partially oxidized again, 

 forming dioxindol. Like dioxindol, it yields crystal 

 lizing salts- with acids, as well as bases. Nitrous acid 

 transforms it in very dilute aqueous solutions into 

 nitrosb-oxindol, C 8 II 6 (]TO)NO, a substance that crystal 

 lizes in long, golden needles, difficultly soluble in 

 water. 



Indol, C 8 IKN&quot;. Is formed when the vapors of oxin- 

 dol are conducted over heated zinc-dust ; or when in 

 digo-blue is boiled with zinc and hydrochloric acid 

 until it is converted into a brownish-yellow powder, 

 and this then distilled with an excess of zinc-dust. It 

 is also formed in small quantity when nitroeinnamic 

 acid is fused with potassium hydroxide with an addi 

 tion of iron filings. Large, colorless laminse similar to 

 benzole acid ; fusing point, 52 ; not distillable alone, 

 but very well with water vapor. Very weak base. 

 &quot;With hydrochloric acid, it forms a difficultly soluble 

 salt, which, when boiled with water, yields free indol. 



Isatyde, C 16 H 12 N 2 4 , is formed by heating isatin 

 with dilute sulphuric acid ; or when its warm saturated 

 alcoholic solution is mixed with ammonium sulphy- 

 drate in a closed flask, and allowed to stand for some 

 time, it being deposited gradually in the form of crys 

 talline scales. It bears the same relation to isatin, as 

 indigo-white bears to indigo-blue. Colorless, fine crys 

 talline inodorous and tasteless substance, insoluble in 

 water, but slightly in alcohol. 



Sulphisatyde, C 16 H 12 N 2 2 S 2 . When sulphuretted 

 hydrogen is conducted into an alcoholic solution of 

 33* 



