As soon as the difficulty of writing with convenience and rapidity on paper, with the ancient carbonaceous ink, became manifest, the resort to the atramentum sutorium as a substitute for the atramentum scriptorium, was a matter of course, and was but a simple adaptation of a familiar substance to a new purpose, requiring no great ingenuity, and no invention whatever.
For a time, perhaps through a period of several centuries, a mixture of the two kinds of ink was employed by the Romans; and this was undoubtedly the best composition that was ever invented for the purpose of deliberate, careful, elegant writing, designed and required to be permanent and unchangeable under constant exposure and handling,—as in the case of manuscript books before the art of printing was known. Even as early as the first century of the Christian era, in the time of Pliny the Younger, and probably long before that, a solution of sulphate of iron was commonly or frequently added to the carbonaceous and oleaginous mixture which we have described as the original writing-ink. In short, the atramentum sutorium was added, in moderate quantity, to the atramentum scriptorium, thus constituting it a chemical as well as a mechanical ink. So, modern ink may be improved in black-
