(3024) Indelible ink.

Manufacturer and builder 6, 1882

It is probable that the practice of laundrymen may he to use washing liquors containing conosiderable more alkali than is the practice in the house-hold. If this is the case, the rapid eating out of the places marked with indelible ink would be easily explained. The indelible ink usually acts by the reduction of nitrate el silver by contact with the fiber, the result being the deposit of a brown or black oxide or sub-oxide of silver in the fiber, which is ineradicable. This action, however, causes a partial destruction of the fiber, and leaves the texture weaker than the other parts of the fabric. The combined action of strong alkali on these stained parts would be likely to effect the destruction of the colored fiber far more rapidly than the use of mild soaps. If our correspondent gets good results from the use of drafteman's India ink, we should say by all means adhere to it. There is nothing in this ink to act
chemically on the fiber, as it consists of carbon in an impalpable state of division; and if he finds it to be sufficiently permanent for practical purposes, we should say it was to be preferred to anything else. We add a good receipt for making an indelible marking ink, though we are not prepared to quarantee that it will stand laundry washing: Dissolve 1 ounce of nitrate of silver and 1½ ounces of crystallized carbonate of soda in separate portions of distilled water, and mix the solutions; collect the resulting precipitate in a filter, wash it thoroughly with distilled water, and introduce it while still moist into a stone mortar; add 8 scruples of tartaric acid, and triturate the whole until effervercence has ceased; next add sufficient antmonia to disso1ve the tartrate of silver, mix in 4 fluid drachms orchil, 4 drachms of white sugar and 12 drachms of finely powdered gum arabic; then asd sufficient distilled water to make 6 ounces of the mixture. Thin ink is said to fulfill ail the conditions that a marking ink should possess. I flows freely from the pen, without running or blotting; it does not require a very strong or long continued heat to develop it; when developed, it is perfectly black, and it does not injure the texture of the finest fabric.