2559. Injurious Effects of Impure Alcohol upon Aniline Colors

2559. Injurious Effects of Impure Alcohol upon Aniline Colors. Dr. Till-manns has examined several varieties of alcohol, and tested the effects upon aniline colors. The most sensitive among these, for impure alcohol, is aniline purple (phenyl-rosaniline). It appears that empyreumatic substances, aldehyde, the peculiar fusel oils due to the substances used in the manufacture of the alcohol, affect the aniline colors when dissolved in such alcohols and boiled therewith. The best test for the purity of an alcohol is to dissolve in it 1 per cent, of perfectly pure caustic potassa, and to heat the solution; it should only acquire a bright yellow color. Another test is to dissolve 1 part of the aniline purple alluded to in 50 parts of the alcohol to be tested, and to heat the fluid for some time. If, after half an hour's heating, no change is observed, the quality of the alcohol is good; but if the latter is not pure enough, the mixture soon becomes turbid, and assumes a red color. Another test is to make two solutions of the color of the same strength (1 in 50), one with alcohol of known purity, and the other with the suspected alcohol, and then compare the intensity and shade of the solutions. Aldehyde is often present in alcohol, especially if it has been purified by means of charcoal.

2560. To Test the Quality of Aniline Colors

2560. To Test the Quality of Aniline Colors. A good and practical way of testing the merits of aniline colors is to have, and keep on hand, a standard and measure of comparison, a sample whose value and coloring power has been ascertained by actual practice, If a new supply of dye stuff is to be tested, weigh out equal quantities of the standard coloring matter and of the one to be tested (say 10 to 30 grains); dissolve them, using the same quantity of alcohol and water, in vessels of as nearly as possible equal size; introduce in each an equal quantity of white wool; place them on a water bath; raise the temperature gradually, and after sufficient time has elapsed, take the two pieces out, dry them carefully, and compare them. That which has been dyed with the best dye, will, of course, show the fullest, brightest, and clearest color. Instead of testing on skeins of wool, Mr. Shuttleworth recommends small squares of white merino or cashmere, as affording a more even surface, and a greater mass of color. A known weight of the dye should bo dissolved in alcohol and added to the bath of warm water, with the necessary mordants. A square of cloth of known weight - say 10 grains - is immersed in the bath, and, after a stated time, removed. The strength and shade of the color can thus be compared with previous samples, dyed under like conditions. It is a good plan to paste these squares, by one edge, in a blank book, noting anything worthy of remark on the margin. The colors are thus preserved from the action of the light, and will be found very useful for reference.