"The lime retains the more fixt part of the arsenick and the sulphurs that come forth are so much the more subtile, as they are separated from what did fix them before, and this appears to be so, because the sulphurs must of necessity pass through all the book to make a writing of a clear and invisible liquor appear black and visible: and to facilitate this penetration the book is strook, and then turned about, because the spirit or volatile sulphurs do always tend upwards; you must likewise clap it into a press, that these sulphurs may not be dispersed in the air. I have found, if that these circumstances are not observed, the business fails. Furthermore that which persuades me that the sulphurs do pass through the book, and not take a circuit to slip in by the sides, as many do imagine, is that after the book is taken out of the press, all the inside is found to be scented with the smell of this liquor. "There is one thing more to be observed, which is, that the infusion of quick-lime and orpin be newly made, because otherwise it will not have force enough to penetrate. The three liquors should be made in different places too; for if they should approach near one another, they would be spoiled. "This last effect does likewise proceed from the defacing liquor; for because upon the digestion of quick- lime and orpin, it is a thing impossible for some of the particles will exalt, stop the vessel as close as you will; the air impregnated with these little bodies does mix with, and alter the inks, insomuch that the visible ink does thereby become the less black, and the invisible ink does also acquire a little blackness." Priceless MSS. in immense number written in periods between the third and thirteenth centuries have been destroyed by modern scholars in experimentations based on the false theory that the faded inks on them, whether above or below other inks (palimpsests), contained iron. Sulphocyanide of potassium is highly esteemed as a reagent for the restoration of writing, if iron is present. Theoretically, it is one of the best for such a purpose if employed with acetic acid. It causes, however, such a decided contraction of parchment as to be utterly useless, but for paper MSS. is excellent. The metallic sulphides generally pronounced harmless, causes the writing to soften and become illegible in a short time. On the other hand, yellow prussiate of potash, with acetic acid in successive operations is of great service in treating the most perplexing palimpsests. Ink which badly corrodes a steel pen need not necessarily be condemned; it may contain just the qualities which make it bind to the paper and render it more durable. Some inks which are fairly permanent against time if not tampered with, can be removed with water. This is true of the most lasting of inks,--the old "Indian." In ancient Latin MSS. the words fuco, fucosus and fucus are found to be frequently employed. It is interesting to note the variations in their meaning: