CHEMICAL SCIENCE. 317 



ON THE EMPLOYMENT OF FERROCYANIDE OF POTASSIUM FOR THE 

 REMOVAL OF RUsf-SPOTS IN WHITE LINEN. 



The employment of ferrocyanide of potassium may often help us out of 

 great difficulties in the case of rust-spots in linen. These do not always 

 consist of common hydratcd oxide of iron, but also frequently of oleatc of 

 iron, which can only he removed with difficulty, and with the assistance of 

 heat, by oxalic acid, or the binoxalatc of potash ; and often not at all by 

 sulphuric or muriatic acid, for these acids can only be applied cold and very 

 dilute, as otherwise the linen suffers. From the high price of oxalic acid, 

 therefore, a, cheap means is wanting, when a great quantity of such iron 

 moulds is to be destroyed. A case of this kind once occurred to the 



V 



author, in which sulphate of iron had been used instead of potash, by which 

 three hundred napkins and other table lined all acquired a rusty yellow color, 

 which, on being washed with soap, instead of disappearing, became darker ; 

 the sulphate of iron being decomposed by the soap, and oleate of iron pre- 

 cipitated upon the fibres. 



Immersion even for several days in water acidulated with sulphuric and 

 muriatic acids produced no effect, because the oleate of iron was not decom- 

 posed. It was here that the ferrocyanide of potassium did such excellent 

 service. It was added in comparatively small quantity to the water, acidu- 

 lated with sulphuric acid, and the linen was then moved about in the fluid. 

 The linen became blue. When all the yellow had disappeared, and a clear 

 blue had made its appearance, the linen was rinsed and treated with solu- 

 tion of carbonate of potash. Here the blue color again disappeared, and 

 with it a great part of the yellow, which only remained in spots. These 

 were then very easily got rid of by dilute sulphuric acid alone. 



The explanation of this process is easy. By the formation of Prussian 

 blue, the oleic acid is separated from the oxide of iron. The carbonate of 

 potash then brought into action combines with the oleic acid, decomposes 

 the Prussian blue, and at the same time also dissolves the greater part of the 

 oxide of iron, so that almost all the iron mould disappears from the stuff 

 simultaneously with the Prussian blue. Caustic ley does not act in the-same 

 way ; it certainly destroys the blue, but the rusty yellow remains, because it 

 has not the same solvent action upon oxide of iron as carbonate of potash. 

 Prof. Runge, Polyt. Centrcdbl 1857, p. 542. 



OX THE APPLICATION OF ANESTHETICS. 



At a recent meeting of the French Academy M. Heurteloup read a paper 

 on the application of anaesthetics. When ether or chloroform is adminis- 

 tered by means of a sponge held at a short distance from the nostrils there is 

 no ascertaining the quantity inhaled, since the breath of the patient or the 

 slightest draught may cause the vapor to deviate. Moreover, in spreading 

 and mixing with the ambient air it mav cause convulsive coughs and other 



o */ 



inconveniences ; and sometimes, after long and fruitless efforts to produce 

 stupefaction, this effect is suddenly obtained to an alarming degree, ending, 



27* 



