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. five or six feet in diameter in the middle, and two feet and a half at the mouth or superior part. The walls 

 are ahout a foot and a half in thickness. To about two-thirds of the height these are constructed with free- 

 Stone, but above that with oven-earth. When the ovens are finished, and quite dry and tight, bundles or 

 faffo'ots of the wood, tied up with hazel or vine rind, arc set upright on the grating; the ligature is cut by 

 means of a blade fixed at the end of a stick; and the pieces are spread about, the interstices being filled with 

 chips. This first layer being properly made, a second faggot is let down, then a third, and so on until Uie 

 oven is full, as high as the hand can reach, when chips and shavings are laid on, to the thickness of three or 

 four inches, and the mouth is covered up with flat stones piled one upon another so as to close all gaps except 

 at the center, where an opening is left four or five inches in diameter. All things being thus prepared, the 

 chips at the top are sef*on fire, and the operators, who from experience are enabled to ascertain when the 

 materials are suiTiciently kindled, seize the proper time to shut up the mouth entirely with a flat stone; and 

 they stop up with earth every interstice from which smoke is seen to escape. The wood then becomes reduced 

 to charcoal, and the resinous part of it, mixed with the sap, flows through the grate down into the cavity 

 at the bottom of the oven. When tliis cavity is fidl up to the place where the iron tube is fixed the tar flows 

 into barrels placed to receive it. It is from custom alone that the persons who superintend the operation 

 ascertain when the wood has given out all its resinous liquor; they then open the top of the oven, removing 

 the stones, and collecting the soot which lodges in their interstices as well as on the sides of the oven, and 

 which forms a kind of lamp-Mack; lastly, they take out the charcoal that has lodged on the grating, and 

 recommence the operation by laying on wood as before. Such impurities as are heavier than the tar, with 

 which they were mixed, remain on the stone that serves as a floor to the oven, whilst the tar itself flows on 

 the surface through the tube, which, as we have remarked before, is five or six inches above the level of the 

 stone. As far as we can judge, all the art of the operation consists in a proper management of the fire, for, 

 if the oven be too closely stopped, the fire is extinguished, the wood is but imperfectly charred, and very 

 little tar is extracted; but il^ on the contrary, the wood burn too briskly, a great proportion of the resinous 

 matter is consumed. When the fire is properly regulated, there is no flame in the oven; the heat and smoke, 

 which are reverberated on the wood, cause the resin and sap to flow from the latter together. It would seem 

 that a more certain mode of regulating the heat would be, instead of closing the top of the oven with stones 

 and turf, to adapt registers of different sizes to a kind of dome, which might form the upper part of it, and 

 render the structure more neat and commodious. 



. . Tar has l)een used as a medicine both externally and internally. The ancients had a high opinion of its 

 eflicacy in pulmonary diseases, supposing it to promote expectoration, relieve dyspnoea, and clieck spitting of 

 blood. Dioscorides particularly speaks of its utility in these cases. He also recommends it to be applied to 

 ulcers, which, he says, it fills up and heals, whether they be situated on the surface of the body, or in the 

 ears, throat, or other internal parts.' In fact, there is no end to the praises bestowed by medical writers 

 on the properties of tar, which, if we are to give credit to all the accounts given of it, is equal to the cure 

 of all the maladies of the human frame. The colleges of London and Edinburgh direct it to be made into an 

 ointment (Unguentum PicisJ ; the former, by means of the admixture of an equal portion of mutton-suet, 

 and the latter, of two-fifths of yellow wax. This ointment has been employed for the cure of cutaneous 

 afiections, particularly those of domestic animals. Some practitioners have applied a plaster of tar for the 

 cure of obstinate cases of Tinea capitis, and not without success; but it is a very painful, and almost a 

 cruel, remedy, for it cannot be taken off without dragging out of the skin adhering to it the roots of the 

 hair, in the eradication of which, in fact, consists the only use of the plaster. 



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TA K, -WATER. 



fjjifusum Picis liquidw pinece.) 

 Aqua picea. Pharm. paup. 



b < 



J* 



Water impregnated with the more soluble parts of tar, and hence called Tar-Water, was once a very 

 popular remedy for various obstinate complaints, both acute and chronic. It was indebted for its great 

 reputation principally to the celebrated Dr. George Berkeley, Bishop of Cloyne, who wrote a long disser- 



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' See also Pliny, lib- 24. c. 7- 



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