TAR. 



TKert is alfo a kind of tar, the projca of making which 

 was fuggeftfd by Bechcr, the celebrated chemift, in the 

 time of king Charles II., w+ich has for fevcral years been 

 prepared from coal in the bifhonric of Liege, and m other 

 parts of Germany : we alfo make confiderable quantities in 

 England, efpecially near Brofcley, in Shroplhire, and at 

 Briilol. In the bilhopric of Liege the coal is diftilled m a 

 Ijind of ftill, compofed of two large caft-iron pots. In 

 England the coal is put into ovens, w-bich are heated by fires 

 lighted under their bottom, and the liquid matter is forced 

 through an iron pipe inferted into the top of the oven, and 

 which communicates with proper condenfing veflels. Wat- 

 fon's Cheni. Eff. vol. ii. p. 346, &c. 



The earl of Dundonald, m Scotland, has lately invented 

 the art of extrafting tar and pitch from pit-coal, by a new 

 procefs of diUillation. See Addiefs and Propofals by fir 

 John Dalryraple, 1784. 



A fubftance refembling tar, called " brai-gras," and much 

 ufed by the French for careening (hips, is made in the follow- 

 ing manner. The oven, defcribed in the preceding part 

 of this article, is ch;u-ged with alternate layers of chips of 

 green wood, and billets of dry, and all the refufe matter of 

 turpentine, &c. Over tlie whole is laid a ftratum of " brai- 

 hee," or rofin, and the gun-barrel pipe is ftopped up, aad 

 not tapped till the whole of the wood is reduced to char- 

 coal. The vault of the oven is alfo covered more carefully 

 after the charge is fufficiently kindled, and the whole pro- 

 cefs is carried on more flowly, and the heat of the fire melts 

 the rofin at the top, which mixes with the refinous fap, and 

 the whole concretes into a dark refinous liqui^ at the bot- 

 tom. When it is fufficiently cooled, it is dra\\Ti off and 

 barrelled. This " brai-gras" is of an intermediate confid- 

 ence between tar and rofin. Aikin's Dift. 



Tar is properly an empyreumatic oil of turpentine, and 

 has been much ufed as a medicine both internally and ex- 

 ternally. 



Tar in fubftance, mixed with honey, has been found an 

 excellent medicine for coughs. 



The ancients efteemed tar good againft poifons, ulcers, 

 the bites of venomous creatures ; alfo for phthifical, fcro- 

 fulous, paralytic, and afthmatic perfons. But the method 

 of rendering it an inoffenfive medicine, and agreeable to the 

 ftomach, by extrafting its virtues in cold water, was un- 

 known to them. Siris, feft. 9. 16, 17. 21. 28. SeeTAK- 

 'UftUer, infra. 



Tar is fometimes given in fubftance, mixed with fo much 

 powdered liquorice, or other fvich powdery matter, as is 

 fufficient to render it of a fit confiftence to be formed 

 into pills. An ointment of tar has been direfted in the 

 pharmacopeias, which has been chiefly employed in cutane- 

 ous diforders. See Unguentum e Pice. 



Dr. Cullen mentions an empirical praftice, with refpeft 

 to tar, which is as follows. A leg of mutton is laid to 

 roaft, and whilft it is roafting it is bafted with tar. Wliilft 

 the roafting is continued, a (harp (l<ewer is frequently thruft into 

 the fubftance of the mutton, fo that the gravy may run out : 

 with a mixture of the tar and gravy found in the dripping- 

 pan, the body is to be anointed for three or four nights fuc- 

 ceffively, and during the time the fame hnen is to be worn. 

 This is alleged to be a remedy in feveral cafes of lepra ; and 

 Dr. Cullen knew one inftance of its having been employed 

 in a lepra ifthyofis with great fuccefs ; but he had no op- 

 portunities of repeating the praftice. 



But the chief ufe of tar is for paying the fides of ftiips 

 and boats, and their rigging, in order to preferve them from 

 the efFeAs of the weather, which would otherwife crack or 

 rot them. 



The tar obtained from the depofition of pyrohgneous 

 acid has been recommended as the beft prefervative for 

 every kind of wood-fence. For this purpofe, it (hould be 

 gently heated in an iron pot, and laid on with a bru(h. It 

 foaks into the wood, and feems to leave no body, as the 

 artifts exprefs it ; but after fome days' expofure to the fun, 

 the furface and texture of the wood will be much altered ; 

 for it will be found fo impervious and hard, that it will be 

 very difficult to make any imprelTion upon it. If a fecond, 

 and efpecially if a third coat of this tar be put upon wood, 

 it will then bear out, as the painters call it, fufficiently well; 

 and Mr. Parkes is of opinion that it will preferve all outfide 

 wood-work much more efFeftually than any other means 

 that have hitherto been employed for the purpofe. For or- 

 namental paling, and all outfide work, a firft, and perhaps a 

 firll and fecond coat of this tar might be ufed with great advan- 

 tage ; and when thefe are dry, white lead and oil might be ufed 

 to finilh the work. This fubftance not only hardens the wood, 

 but effeftually preferves it from worms and from all other 

 infeifts. It will (lop the progrefs of decay, when wood has 

 become worm-eaten. It is obferved, however, that this tar 

 is very difterent from that which is diftilled from mineral 

 coal, but which the earl of Dundonald recommended for a 

 fimilar purpofe. The appearance of the application may 

 be ver)' confiderably improved by the following prepara- 

 tions ; w'z. I gallon of tar, i oz. of tallow, 2 oz. of pul- 

 verized rofin, melted together and put on warm ; — or, 

 I gallon of the tar and 2 oz. of pulverized fulphate of iron, 

 ufed as the other. This tar has alfo been found an ufeful 

 varnifh for articles made of rolled iron, or of caft-iron. A 

 beautiful varni(h for thefe purpofes may be formed by in- 

 tin.ately mixing in a gentle heat one gallon of the wood-tar 

 with half a pint of reftified fpirits of wine. If this be laid 

 on hot and properly hardened, it will prove a beautiful and 

 durable black varni(h. Parkes's Chem. EfT. vol. ii. 



Tar may fometimes be found ufeful as an application for 

 cuts in (heep by chpping, and alfo to the parts affefted by 

 the fly ; as well as in thofe of many other forts of animals. 

 It is likewife apphed to the axles of wheel-carriages, in order 

 to prevent friftion, and might probably be ftill more bene- 

 ficially made ufe of in this intention, by having a portion of 

 black-lead incorporated with it, as it would laft longer, and 

 be, at the fame time, more powerful in obviating the effefts 

 of friftion. 



It is a material which has alfo been recommended for being 

 applied to the parts of trees from which boughs are taken ; 

 in which cafes, the faces of the wounded parts and the edges 

 of the bark are to be made perfeiftly fmooth by means of 3 

 proper knife ; and in a few hours afterwards, or as foon as 

 the parts are become quite dry, they are to be carefully 

 plaillered over with the tar, which is fimilar to that employed 

 for fmearing of (heep ; or they may be laid over with white or 

 blue lead paint, well mixed with oil, and made rather thicker 

 than that commonly ufed in painting. The tar is, however, 

 certainly preferable, being of a more adhering, healing na- 

 ture ; and, when laid on in a thin ftate, is not fo apt to fall 

 off in a fcaly manner by the aftion and effefts of the weather, 

 as is the cafe with the other fubftances. 



As the component parts of vegetable tar have been found 

 toconfift of oil, refinous matter, pyrohgneous acid, and water ; 

 that which is of the fineft brown colour, has the leaft acri- 

 dity, and which is the freeft from a dark black appearance, 

 is probably the beft and moft proper for ufe in apphcations 

 as dreffings to animals ; though the other kifids may be 

 equally or more beneficial in different other intentions. 



Tar, when in intimate mixture and union with butter or 

 lard, and the different precipitates of mercury or fulphur, 



fonnf 



