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London : Printed for the Author; 1770, 8°, 170, 20 pp., 44 engraved plates (the 2 repating plates are missing), comtemp. leather; rebacked, fine copy. First Octavo Edition of "The Construction of Timber, From its Early Growth : Explained by the microscope, and proved from Experiments, In a great Variety of Kinds : In Five Books. On the Parts of Trees ; their Vessels; and their Encrease by Growth: And on the different Disposition of those Parts in various Kinds ; and the Particularities in their Vessels. With Figures Of Their various Appearances; of the Instrument for Cutting them ; and of the Microscope thro' which they were viewed. By John Hill, M.D. member of the Imperial Academy. London : Printed for the Author; and sold by R. Baldwin, in Pater-Noster-Row; J. Ridley, in St. James's-Street; J. Nourse, T. Becket, P. Elmsly, J. Campbell, in the Strand; and T. Davies, in Russel-Street, Covent-Garden." "The most important work to be published on the subject during the eighteenth century." Henrey "The first use of dyes in histology. Hill (1770) had employed dyes in studying the microscopic structure of timer, and that beyond the question, his work was actually histological in nature. His methods in fact, were more like modern histology than the subsequent work of Ehrenberg." H.J. Conn, The History of Staining (1933), p.9 "Hill did not rely on any one method, but studied the structure of stems in many ways. He used a more elaborate method of maceration than Martin, and was the first to use maceration in the study of wood, sinking a loose wicker basket containing the sticks he wished to study into a stream until the tissues were well softened. This identical method, which was rediscovered by the younger Moldenhawer in 1812, is considered by Sachs as one of the great steps in the progress of phytotomy. Hill also makes the first mention of a method of preservation of material for further study. The practice of dropping the macerated pieces of wood into a solution of alum and then transferring them to spirits of wine, after thoroughly drying, resembles in a very crude manner our modern method of fixing and hardening. The reason for this is seen in his statement that 'Nothing but spirit of wine can preserve these tender bodies, and, till I found this method of hardening them first, the liquor often destroyed them. . . . " "Hill is undoubtedly the first to have used staining as an aid in the study of microscopical anatomy of plants. He prepared an alcoholic tincture of cochineal, in which, after it had been filtered, he placed the stems of plants for a while, discarding that portion which had been immersed in the fluid when he made his sections. Another method of staining used was even more advanced since it involved a mordanting of the tissues before developing the color. A solution of sugar of lead was prepared, filtered, and put in a tea-cup and the sticks to be studied were allowed to remain in this fluid for two days. An essential part of this operation was the 'whelming' of the tea-cup with a wineglass to prevent the drying of the material. While the tissue was soaking in the lead solution he prepared a solution of quick lime and orpiment in water and then transferred the material from the tea-cup to the second solution for two days. When the sticks were first placed in the second solution they were colorless, but in a short time they became deep brown. By means of this staining he was able to demonstrate the existence of structures invisible in the uncolored material. A third method, which was an injection rather than a staining process, was by careful drying of the wood and boiling it in green sealing wax. By this procedure the vessels became thoroughly impregnated with the green sealing wax and the 'split pieces resemble striped satins, in a way scarce to be credited.' " "Writers concerning the history of the microscope generally describe the 18th century as being barren of developments .
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