The common writing inks being liable to be obliterated by many chemical agents, several compounds more capable of resisting these agents have been proposed; of which the following appear deserving of notice.

1. Carbon Ink. Dissolve real Indian ink in common black ink; or add a small quantity of lamp-black previously heated to redness, and ground perfectly smooth, with a small portion of the ink.

2. Stephen's (patent) Carbon Ink. Common soda of commerce is mixed with resinous matters (as shell-lac or resin), in about equal parts by weight. Water being added according to the strength required, the solution is boiled until the resin has become dissolved. Mix in a mortar with the requisite quantity of fine lamp-black, and add any suitable coloured solution.

3. Shell-lac, Ink or Coathupe's Writing Fluid. To 18 oz. of water add 1 oz of powdered borax', and 2 oz, of bruised shell-lac, and boil them in a covered vessel, stirring them occasionally, till dissolved. Filter, when cold, through coarse filtering paper; add 1 oz. of mucilage; boil for a few minutes, adding sufficient finely powdered indigo and lamp-black to colour it. Leave the mixture for 2 or 3 hours for the coarser particles to subside; pour it off from the dregs, and bottle it for use.

4. Gluten Ink. Dissolve wheat gluten, free from starch, in weak acetic acid of the strength of common vinegar mix 10 grs. of lamp-black and 2 grs. of indigo with 4 oz. of the solution, and a drop or two of oil of cloves.

5. Haussmann's. Dissolve 1 part of genuine asphaltum with 4 parts of oil of turpentine, and sufficient lamp-black. If sufficient lamp-black be used to give it a suitable consistence, it may be used with types.

6. Braconnet's Indelible Ink. Take 20 parts of Dant-zie potash, 10 of tanned leather parings, and 5 of sulphur; boil them in an iron pot with sufficient water to dryness; then raise the heat, stirring the matter constantly, till the whole becomes soft, taking care that it does not ignite. Add sufficient water, and filter through cloth. It must be kept from the air. It flows freely from the pen, and resists many chemical agents; but it is not strictly indelible.

7. Dr. Normandy's Indelible Ink. Frankfort lampblack 24 lbs., to be ground with mucilage, made by adding 24 lbs. of gum to 60 gallons of water, and the mixture filtered through a very coarse flannel; 4 lbs. of oxalic acid are then added, with as much decoction of cochineal and sulphate of indigo as will yield the shade of colour desired.

8. Indian Ink. Real lamp-black, produced by combustion of linseed oil, ground with gum, and infusion of galls. It is prepared both in a liquid and solid form, the latter being dried in the sun.

9. Gold is mixed with Indian ink, equal parts.

10. Puscher's Indelible Ink. Dissolve 4 parts of aniline black in 16 parts by weight of alcohol, with 60 drops of strong hydrochloric acid, and dilute the solution with 90 parts by weight of water in which 6 parts of gum arabic have been previously dissolved. It is said not to act upon steel pens, nor be altered by alkalies or acids.

Indelible Ink, for printing Cotton and Linen fabrics intended for chlorine bleaching. One part of coal-tar mixed with one part of benzine, and one tenth part of lamp-black. It can be made thicker or thinner by using more or less benzine. - Pharm. Journal.