2474. Ink Powder

2474.    Ink Powder. For an ink powder take 1 pound nut-galls, 7 ounces copperas, and 7 ounces gum-arabic. Pulverize and mix. This amount of ink powder will make 1 gallon of good black ink. Two or three powdered cloves should be mixed with each pound of powder, to prevent moulding.

2475. Permanence of Ink

2475.    Permanence of Ink. The great difficulty with all iron inks is the precipitation which will take place, after a longer or shorter time, and which manufacturers have tried to obviate by substituting other materials. All inks, however, the basis of which is not tan-nate and gallate of iron, are not black immediately, and consequently not so agreeable to the eye when using them. The alizarine or rather indigo inks have a greenish, the chromium inks a reddish hue, and are not better adapted to withstand chemical agents than iron inks are.

2476. To Keep Ink from Thickening

2476.   To Keep Ink from Thickening. The only way to keep writing ink thin with which we are acquainted is to protect it from the atmosphere. The air not only evaporates it, but oxidizes it and renders it thick. Those ink-stands which have a tapering funnel in the mouth will preserve the ink in its normal state much longer than the ordinary kind, because less of the surface is exposed.

2477. Writing Fluids

2477.    Writing Fluids. The very general use of steel pens has caused a corresponding demand for easy flowing inks, many of which have been of late years introduced under the title of "writing fluids," or "steel pen ink." These are mostly prepared from galls in the preceding manner, but a less quantity of gum is employed. The blue writing fluids, which either maintain their color or turn black by exposure, are prepared from the ferrocyanide of potassium (prussiate of potassa), or from indigo.

2478. Beautiful Blue Writing Fluid

2478.    Beautiful Blue Writing Fluid. Dissolve basic or soluble Prussian blue in pure water. This is the most permanent and beautiful ink known. It is not affected by the addition of alcohol, but is immediately precipitated by saline matter. The precipitate, however, still possesses the property of dissolving in pure water.

2479. To Test Prussian Blue

2479.    To Test Prussian Blue. Pure Prussian blue feels light in the hand; adheres to the tongue; has a lively dark blue color, and gives a smooth deep trace. It should not effervesce with acids, as when adulterated with chalk; nor become pasty with boiling water, as when adulterated with starch. Prussian blue, rendered inferior in its color by an admixture of free oxide of iron, may be improved by digestion in dilute sulphuric or muriatic acid, washing and drying. Its relative richness in the real ferroprussiate of iron may be estimated by the quantity of potash or soda which a given quantity of it requires to destroy its blue color.