022 CONIFERS. 



furnishes Toluol or Toluene, CO' (boiling point 114° C), Xylole 0'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 PyrocatecMn. 

 They are easily sublimed at some degrees above their fusing point 

 (104° C), or removed by acetic acid, in wdiich as wxll as in water they 

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

 occur, it having probably been removed by w^ator. 



Pyrocatechin, C*H'(OH)', 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 tannin 

 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 exhaustmg 

 them with water. Ether when shaken wath the concentrated aqueous 

 solution and left to evaporate, leaves colourless crystals of pyrocatechni 

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

 burning persistent taste, and are very pungent and irritating when 

 allowed to evaporate. A solution of pyrocatechin yields with perchlonde 

 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 

 Aqua vel Liquor Picis, made by agitating wood-tar with water. _ ine 

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

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

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

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

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

 preferred." 



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

 shipped from various ports in the Gulf of Bothnia, as Uleaborg, Oai«ia 

 Carleby, Jacobstad, Ny Carleby and Christinestad ; also from Archangel 

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

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



The North of Sweden likewise produces tar, chiefly about vt^^^ 

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

 apparatus of iron. . ■ 



The pine forests of North America aflTord tar and pitch. Wdmingto 

 in "NTnrfVi no,.r.i;^r. rv^,.^v.+^.i :^ 10^71 OK oi?A i.or.T.oia nf Lir. anu oio^ 



in North Carolina exported in 1871, 25,260 barrels of tai 

 barrels of pitch.^ 



United King 



189,291 



We may suppose that the authors of the ma 



French Codex were not of this opinion, in- - ^un^u. ,. ^.^^^, --.-. rr,n,idar /'- 



asmuch as m making Eau de Goudrov, they Forth and South Carohm-to^^ ^^^^.,_ 



order that the liriiiid obtained by the first pwts presented to Parliament, -VJ^V' 



aeration of the tar. shall be thj^wn .-^^ 

 Consul W^\^ci;Bfrort onthjj^'^. ^^. 



