27 G ANNUAL OF SCIENTIFIC DISCOVERY. 



PROCESS FOR DECOLORIZING THE FATTY OILS. 



M. Brunner states that he has been most successful in bleaching fatty oils 

 by proceeding as follows : 



The oil is made into an emulsion with water, to which the proper consist- 

 ence is given by gum or starch paste, and this emulsion is well worked up 

 with thoroughly ignited charcoal, coarsely powdered and freed from fine 

 dust by sifting. To one part of oil about two parts of charcoal powder are 

 taken. The doughy mass is allowed to dry thoroughly at a temperature 

 which should not exceed 212 F., and the oil is subsequently extracted with 

 ether in the cold in a displacement apparatus. After this extract has depos- 

 ited any charcoal powder that may have passed through during the extrac- 

 tion, it is put into a retort, and the ether is distilled off in the water-bath. 

 In this way olive oil and walnut oil are completely deprived of color. It 

 might perhaps be supposed that the charcoal has a direct decolorizing action 

 in this case upon the oil, just as in many cases it clears many aqueous fluids. 

 This, however, is not the case. Oils left in contact with charcoal for weeks 

 together did not undergo the least decolorization, even when they were dis- 

 solved in ether and digested with charcoal. The presence of the water con- 

 tained in the emulsion appears first to give rise to the action. It is probable 

 that by the preparation of the emulsion, the coloring matter, which does 

 not belong to the oil itself, is taken up by the water, and afterwards absorbed 

 by the charcoal. The action may be similar to that set up in the operation 

 employed by painters to bleach oils, which consists in agitating the oil 

 sufficiently with an equal volume of water, and exposing the mixture to the 

 sun. The water, which soon separates again from the oil, appears turbid, 

 and often mixed with slimy flakes. The operation is repeated for weeks, 

 the water being frequently renewed, until it is no longer rendered turbid, and 

 the oil often appears limpid. In the above process the essential part appears 

 to be the complete desiccation of the charcoal mixed with the emulsion. If 

 the oil be extracted with ether before this is the case, it is obtained again 

 with its original color. 



Lastly, it is to be remarked that by this process the oils undergo a very 

 remarkable thickening. Thus walnut oil is obtained nearly of the consist- 

 ence of butter. Bremer Mittheilungen, Dec. 1857. 



NEW MEDIUM FOR PAINTS, 



A recent improvement in the preparation of paints is thus described by 

 the discoverer, M. Sorel, in the following communication to the French 

 Academy : 



In 1855 I had the honor of presenting to the Academy various products 

 obtained by means of oxychloride of zinc, especially cements and mastics, 

 as hard as marble, and quite insoluble in water, and a paint, equally insoluble, 

 intended to replace, very economically, oil and other painting. This paint 

 had the inconvenience of being difficult to use, and of requiring, like silice- 

 ous painting, the application of a liquid on the last layer to fix it and 

 render it insoluble; when I wished to avoid the use of this liquid by 

 rendering my paint more drying, I was met by an equally sei'ious incon- 

 venience: the paint thickened very rapidly in the vessel, and there was not 

 time to use it. I have now succeeded, by adding certain substances to iny 



