The doctrine of Puzzolana is thus—“it is an ash-powder, or rather pullverised cinders, found various-coloured about Naples, & black-coloured on Vesuvious. They dig it white and grey in the hills near Puzzuolo; brown and yellow at the foot of Vesuvius. It is likewise found near Rome in the before mentioned colour and reddish. It is produced by consumed cinders & scorified Lavas;—The Ancients employed the puzzolana likewisse in the neighberhood of Rome in the public roads;—The black puzzolana is said to be excellent in buildings underwater; and the Ancients are said to have employed it on such occasions more than any other. However, other species duely mixed and prepared may answer the same purpose.”—Thus much prefatory to my demand on you for another Crucible—for, in my late experiments, the one you saw me bury some time ago, has been destroied—Pushing my theories, grounded upon the ’foregoing extracts—I believe that, from the Shale, I can demonstrate, most probably an intimate affinity, not only in colour, but in chemical properties, and apparent constituents, between this Shale, and the several species & qualities of the Puzzolana (The only analysis of this substance, now at my command, is thus—Silex 55 to 60, Alumine 19 to 20, iron 15 to 20, Lime 5 to 6.—) and, that all the varieties found to exisst in Puzzolana, are in fact, produceed by the different1 degrees of heat,2 and, very probably, the causal-co-agencey3 of water. I have already made the Shale assume every color, and appearance, aforesaid, exceept the white: this I still expect may be done (not by me perhaps); and, that by pursuing the subject, it is possible to produce an accordance with the following Sientific description of puzzolana—“It usually occurs in small fragments of friable masses, which have a dull, earthy aspect and fracture, and seem to have been baked. Its solidity does not exceed that of Chalk. It is seldom tumified; and its pores are neither so large nor numerous, as those of Scoria. Its colours are grey or whitish, reddish, or nearly black. By exposure to heat, it looses its power of effecting the Needle, and melts into a black Slag—”

If you ask, my good friend, why all this fuss and trouble?—I answer, that the Shale has been proved to be very far superiour to M. Hill: that it is unquestionably a substance, by a true understanding of the act of burning it (which I regret I have not yet satisfied myself of) may be rendered in any required quantities,4 with properties fully equal to Puzzolana—a Desideratum in the Arts, worthy the Patronage of the Nation—altho, ’tis to you alone, that the public will have all the benefits of your purer, and my foolish whims, after I5 shall have passed away as a speculative Maniac—I verily do believe Sir, that this subject, in the hands of some professional Engineer, or, Illuminati of the Dock and James River Companies, might be brought to an important public issue, its having been the project of a Native Virginian, to the contrary Notwithstanding! This is my Ne plus, without funds! And, if you can prevail on any of your Sientific friends to controvert my conclusions, it may save you ferther risque, and, wou’d be thankfully acknowledged by your