Such are the _principal_ patents, suggestions, and inventions, up to the year 1856; but there are many more which have been brought before the public, some of which we will now describe. Dr. Darwin, some years since, proposed absorption, first, of _lime water_, then of a weak solution of _sulphuric acid_, drying between the two, so as to form a gypsum (sulphate of lime) in the pores of the wood, the latter to be previously well seasoned, and when prepared to be used in a dry situation. Dr. Parry has recommended a preparation composed of _bees-wax_, _roll brimstone_, and _oil_, in the proportion of 1, 2, and 3 ounces to ¾ gallon of water; to be boiled together and laid on hot. Mr. Pritchard, C.E., of Shoreham, succeeded in establishing _pyrolignite of iron_ and _oil of tar_ as a preventive of dry rot; the pyrolignite to be used very pure, the oil applied afterwards, and to be perfectly free from any particle of ammonia. Mr. Toplis recommends the introduction into the pores of the timber of a solution of sulphate or muriate of iron; the solution may be in the proportion of about 2 lb. of the salt to 4 or 5 gallons of water. An invention has been lately patented by Mr. John Cullen, of the North London Railway, Bow, for preserving wood from decay. The inventor proposes to use a composition of _coal-tar_, _lime_, and _charcoal_; the charcoal to be reduced to a fine powder, and also the lime. These materials to be well mixed, and subjected to heat, and the wood immersed therein. The impregnation of the wood with the composition may be materially aided by means of exhaustion and pressure. Wood thus prepared is considered to be proof against the attacks of the white ant. The process of preserving wood from decay invented by Mr. L. S. Robins, of New York, was proposed to be worked extensively by the “British Patent Wood Preserving Company.” It consists in first removing the surface moisture, and then charging and saturating the wood with hot _oleaginous vapours_ and compounds. As the Robins’ process applies the preserving material in the form of vapour, the wood is left clean, and after a few hours’ exposure to the air it is said to be fit to be handled for any purposes in which elegant workmanship is required. Neither science nor extraordinary skill is required in conducting the process, and the treatment under the patent is said to involve only a trifling expense.