Accumulated evidence may be said to establish itself in the light of investigation and experience and becomes more and more a certainty when considered, reviewed and discussed in connection with a chronological history of the "gall" inks since they came into semi-official and other uses centuries ago. Descriptions of MSS. containing ink writings hundreds of years old, many of them as legible as when first written, are silent witnesses whose testimony cannot be assailed. Such information when assembled together minimizes many of the conditions which have existed and interposed in preventing during the last four decades a general adoption or re-adoption of such a tanno-gallate of iron ink, the lasting qualities of which some of our forefathers estimated would, and as we know have stood the test of time. Assuming this character of ink to have been employed in past centuries, the cause or causes for the differentiations in respect to color and durability become of paramount importance. The investigations of the writer in this direction, while in some respects traveling the same road followed by others, diverged from them and has been more in the nature of a comparative analytical and microscopic examination of ancient with ancient and modern with modern documents in connection with numerous chemical experiments, the manufacture of hundreds of inks and the study of their time and other phenomena. To accomplish this, ancient documents not written with "Indian" ink, but with those obviously containing combinations of iron and galls or other tannins, were selected and grouped into color families. They began with the fourteenth century, continuing well into the nineteenth, to the number of nearly four hundred, each of them of a different date and different year. Some of them were so pale and indistinct as to be illegible, others less so and by gradual steps they approached to a definite black; many of them as rich and deep in color as if they had been written not centuries ago but within a few years. Signatures on the same document represented different degrees of color, so that the question of the material on which the writing appeared affecting the appearance of the ink, was not a factor; but the difference in the inks used to make the signatures was the determining factor. At this point it may be noted that the investigations conducted by Mr. Swan before referred to and those by the writer and the resultant observations of each were substantially alike. Many of the writer's, however, preceded those of Mr. Swan's, for during the years 1885 and 1886, having had the custody of part of the Archives of the City of New York there were many opportunities to study this subject which were taken advantage of, before and after which time frequent examinations were made of writings much more ancient than those pertaining to New York.