Experiments Nos. 1, 2, and 3 relate to the Earle process, from which great results were expected from 1839 to 1844. It consisted in immersing timber, rope, canvas, etc., in a hot solution of one pound of sulphate of copper and three pounds of sulphate of iron mixed in twenty gallons of water. It was first tested on some hemlock paving blocks on Chestnut Street, Philadelphia, and for a time seemed to promise good results. Experiments with prepared rope, exposed in a fungus pit, by Mr. James Archbald, Chief Engineer of the Delaware and Hudson Canal, seemed also favorable. The process was, therefore, thoroughly tried at the Watervliet Arsenal, where it was applied to some 63,000 cubic ft. of timber, at a cost of about seven cents per cubic foot. The timber was used for various ordnance purposes, and while it was found to have its life extended, as would naturally be expected from the known character of the antiseptics used, its strength was so far impaired, and it checked and warped so badly, that the process was abandoned in 1844. The committee is indebted to General S.V. Benet, Chief of Ordnance, for a full copy of the reports upon these experiments. Experiments Nos. 4 and 7 represent the lime process, which has been applied to a considerable extent in France. The fact that platforms and boxes used for mixing lime mortar seem to resist decay has repeatedly suggested the use of lime for preserving timber. In 1840 Mr. W.R. Huffnagle, Engineer of the Philadelphia and Columbia Railroad, laid a portion of its track on white pine sills, which had been soaked for three months in a vat of lime-water as strong as could be maintained. Similar experiments were tried on the Baltimore and Ohio in 1850. The result was not satisfactory, as might be expected from the fact that lime is a comparatively weak antiseptic (52.5 by atomic weight, while creosote is 216), and from the extreme tediousness of three months' soaking. Experiments Nos. 5 and 8 were tried with sulphate of iron, sometimes known as payenizing, and the particulars of the former have been furnished by Mr. I. Hinckley, President of the Philadelphia, Wilmington, and Baltimore Railroad, to whom your committee is much indebted for a large mass of information on the subject of timber preservation. Mr. Hinckley has had longer and more varied experience on this subject than any other person in this country. Beginning with sulphate of copper in 1846, following with chloride of mercury in 1847, and chloride of zinc in 1852, going back to chloride of mercury, and again to chloride of zinc, using the latter until 1865, then using creosote to protect the piles against the _teredo_ at Taunton Great River (experiment No. 2. creosoting), he has had millions of feet of timber and lumber prepared by the various processes, and has kindly placed at our disposal many original reports in manuscript and pamphlets which are now very rare.