chemical agents (whether acids, alkalies, saline bodies or elements,) as well as the ancient inks, is the result of a necessity existing in their very composition and invention, and even in the use for which they were designed, and to which they are applied. A dye (like modern ink) is the result of chemical action, and is therefore subject to chemical re-agents; yet, when well made, it is proof against mechanical action, such as washing, rubbing, and scraping; nor can it be removed from paper to which it is applied, without destroying that material, or rendering that part of it practically useless. But, on the other hand, the ancient inks, which resist all chemical processes can be removed by mechanical action, such as has been named. If a new ink were compounded of the two, possessing the best properties of each, any writing executed with it could be effaced by the joint or successive action of mechanical and chemical applications.
It must be borne in mind that the ancient inks had one use for which writing ink is now never required; and that was in making books, or multiplying copies of manuscripts indefinitely for general reading, or publication. The invention and universal employment of the art of printing has wholly done away with that.
