622 CONIFERS. 



furnishes Toluol or Toluene, UO^ (boiling point 114° C), Xylole Q'W\ 

 and several other analogous substances. 



If tar is redistilled, an elevated temperature being used towards the 

 end of the process, some crystallizable solid bodies are obtained, the 

 most important of which is that called Paraffin, having the formula 

 Qnjj2n+2^ ^ Varying from 20 to 24. 



The crystals already mentioned as occurring in tar are Pyrocatechin. 

 They are easily sublimed at some degrees above their fusing point 

 (104° C), or removed by acetic acid, in which as well as in water they 

 are readily soluble. Hence in some sorts of tar this substance does not 

 occur, it having probably been removed by water. 



Pyrocatechin, 0*^11^(011)^ can be obtained by the destructive distil- 

 lation of many other substances, as catechu, kino, the extracts of rhatany 

 and bearberry leaves, and other extracts rich in that form of taimin 

 which produces greenish (not blue-black) precipitates in salts of iron. It 

 is extracted from the granular sorts of wood-tar, by exposing them at a 

 proper temperature to a current of heated dry air, or by exhausting 

 them with water. Ether when shaken with the concentrated aqueous 

 solution and left to evaporate, leaves colourless crystals of pyrocatechin 

 which after purification are devoid of acid reaction. They have a peculiar 

 burning persistent taste, and are very pungent and irritating when 

 allowed to evaporate. A solution of pyrocatechin yields with perchloride 

 of iron a dark green coloration changing to black after a few moments, 

 and becoming red on the addition of potash. This mixture finally 

 acquires a magnificent violet hue, like a solution of alkaline perman- 

 ganate. No alteration is produced in a solution of pyrocatechin by 

 protosalts of iron. 



Among the few medicinal preparations of tar, is Tar Water, called 

 A qua vel Liquor Picis, made by agitating wood-tar with water. The 

 presence in it of pyrocatechin is easily proved by the above-mentioned 

 reactions, or by a few drops of red chromate of potassium, which pro- 

 duces a brownish black colouration. It may hence be inferred that 

 pyrocatechin is perhaps the active ingredient in tar-water, and that 

 for making this liquid the granular, crystalline sorts of tar should be 

 preferred.^ 



Commerce — Tar as well as pitch is manufactured in Finland, and 

 shipped from various ports in the Gulf of Bothnia, as Uleaborg, Gamla 

 Carleby, Jacobstad, Ny Oarleby and Ohristinestad ; also from Archangel 

 and Onega on the White Sea. Some tar is also produced in Volhynia, 

 and finds its way by the Dnieper to the Black Sea. 



The North of Sweden likewise produces tar, chiefly about Umea 

 and Lulea, the distillation being now performed in well-constructed 

 apparatus of iron. 



The pine forests of North America aflford tar and pitch. Wilmington 

 in North Carolina exported in 1873, 25,260 barrels of tar, and 8788 

 barrels of pitch.^ 



The imports of tar into the United Kingdom in 1872, were 189,291 



' We may suppose that the authors of the maceration of the tar, shall be thrown away. 



French Codex were not of this opinion, in- '^ Consul Walker, Report on the Trade of 



asmuch as in making ^aw fZe Ccwrfro?;, they Aorth and South Carolina — Consular Be- 



order that the liquid obtained by the first ports presented to Parliament, Ma}% 1872. 



