The wool is first stripped off the skins, which are plunged in a lime-pit for the space of 24 hours, then taken out, drained, and stretched on a kind of frame ; when the flesh is scraped off by means of an iron instrument. Next, they are moistened with a wet rag, then sprinkled with pulverized chalk, rubbed with a pumice-stone, and afterwards with the instrument ; when the skins are again moisten-ed, rubbed with the pumice-stone, drained, and the iron instrument is passed a third time over them.-The wool, or hair-side, undergoes similar operations ; and, the whole being carefully extended on the frame, the flesh-side is again scraped : when it is a second time sprinkled with pulverized chalk, which is afterwards gently brushed off, and the skin again suspended, that it may become perfectly dry.
The next operation is that of paring; when the skins are reduced to one half of their thickness; and rendered smooth by the action of the pumice-stone. The parings are consumed in making size, glue, etc. while the skin is employed for ingrossing deeds, and other purposes.
There is a finer sort of parchment, known under the name of vellum, which is prepared from the skins of sucking calves. It is manufactured in a similar manner with the first mentioned article, excepting that it is not immersed in the lime-pit.- A very excellent glue, or cement, may be obtained by boiling the small shreds of vellum, so as to convert them into a jelly ; but care should be taken that no fragments of parchment be used, because the skins of goats and sheep are unfit tor such purpose.
A patent was lately granted to Mr. Hitchcock, for converting old skins of parchment or vellum into leather.- Although we doubt the practical tendency of the patentee's ingenious, but complicated processes; yet, in the present instance, as they may be applied to other useful purposes, we shall observe, that he endeavours first to reduce the skins to their natural state, by washing them well and often in water for 24 hours ; then removing them for a similar time to a bath composed of l 1/2 lb. of white vitriol, 1 lb. of cream of tartar, and 1 oz. of sal ammoniac, dissolved in 20 gallons of water. In order to soften their texture, and to discharge the lime, he adds to this liquor lOlb. of oil of vitriol, 1 lb. of aqua-fortis, and one pint of spirit of salt ; in which acid bath the skins are to be steeped only for a short time. After washing them properly, rinsing out all the acid, and completely wringing out the water, without tearing the skins, they are to be immersed and well soaked in a tanning liquor, composed of 20lbs. of oak-bark, 7 lbs. of sumach, 5 lbs. of elm-bark, 3 lbs. of sassafras, and the same quantity of lignum-vitae shavings mixed with 20 gallons of water, previously warmed (proba-bly, boiled), for 12 hours, and cooled to the temperature of new milk, before the skins are immersed. Next, they are to be tanned in the common way, with oak-bark, or oak and sumach, then washed and dried. Lastly, to make the renovated leather water-proof, it should first be soaked for five or six days in linseed or nut-oil; and, after wringing out the superfluous oil, the skin ought to be repeatedly dressed with the following composition : Take 7 lbs. of nut, or linseed oil ; red-lead, litharge, sugar of lead, white vitriol, bees-wax, resin, and pitch, l 1b. of each: melt them together over a moderate fire.