ulkaUzed Oxide of Iron i?i Calico Printing. 3 £5 



the green oxide remains united with it in consequence of 

 its cohesion. 



If hnen or woollen yarn be imbibed in nitrous acid 

 diluted with more or less water, or any other hyper- 

 oxygenated solution of iron, and then be exposed for some 

 minutes to a caustic alkaline ley, a beautiful nankeen co- 

 lour will be produced. Instead of this nitrous solution, a 

 solution more or less diluted of sulphuric acid may be em- 

 ployed. Many articles when taken from the caustic ley 

 are dirty, but when they have attracted the oxygen of the 

 atmosphere, they acquire the proper brightness. These 

 colours pass to violet and black by maddering. They will 

 acquire a deep black colour, as well as different shades of 

 gray, when treated with gall-nuts, sumach, or logwood. 

 Several blue shades may also be obtained from them, by 

 employing a ley of alkaline prussiate, or calcareous earth, 

 oxygenated by any acid. The various shades of morose 

 gray are produced by stronger or weaker infusions of gall- 

 nuts, which must be suffered to dry on the }'arn impreg- 

 nated with them ; after which the yarn is immersed in sul- 

 pharic, nitric, muriatic, or acetic acid, diluted with water. 



A nitrous solution of iron, when freed from its acid by 

 evaporation, and when the residuum is brought to a white 

 heat in a crucible, gives an oxide of iron which is an excel- 

 lent polisher of steel. The case is the same with a solution 

 of iron in sulphuric acid ; but in this case the oxide must 

 be longer exposed to heat. A muriatic solution of iron 

 may be employed for the same purpose ; but the acid, 

 when evaporated by a strong heat, carries with it a large 

 portion of the oxide. All methods in general, by which 

 iron can be sufficiently oxygenated, will produce an oxide 

 fit for the polishing of steel. 



I must here mention an experiment which I communi- 

 cated about ten years ago to my friends Wild and Arbogart. 

 Having once tried to oxygenate oxide of iron as much as 

 possible in order to convert it into acid, I mixed together, 

 in the course of several unsuccessful experiments, a pound 

 of a nitrous solution of iron and half a pound of concen- 

 trated sulphuric acid. When the mixture was evaporated 

 to dryness in a porcelain dish, there remained a white re- 

 siduum, entirely insipid. On examining it several weeks 

 after, I Ibund that it had attracted moisture, and had 

 assumed an astringent taste. A few weeks after, when a 

 certain portion of it had dissolved in the moisture which 

 this residuum had attracted from the atmosphere, I poured 

 X3 ofT 



