FIX NIGRA. 623 



barrels, valued at £218,339. Of this quantity 145,483 barrels were 

 shipped from the northern ports of Russia. 



The barrels in which tar arrives hold about 30 gallons. Smaller 

 sized vessels termed half-barrels are also used, though less frequently. 



Uses — In medicine of no great importance : an ointment of tar is a 

 common remedy in cutaneous diseases, and tar water is sometimes taken 

 internally. The consumption of tar in ship-building and for the 

 preservation of fences, sufficiently explains the large importations. 



Other Varieties of Tar. 



Junijwr Tar, Pyroleum, Oxycedri, Oleum Juniperi empyreuma- 

 ticum, Oleum Cadinicvi, Huile de Cade. — This is a tar originally ob- 

 tained by the destructive distillation of the wood of the Cade, Juniper us 

 Oxycedrus L., a shrub or small tree, native of the countries bordering 

 the Mediterranean. It was for centuries used in the South of France as 

 an external remedy, chiefly for domestic animals, but had fallen into 

 complete oblivion until ten years ago, when it began to be prescribed 

 in skin complaints. 



The Huile de Cade now in use, is transparent and devoid of crystals. 

 It is somewhat thinner than Swedish tar, but closely agrees with it in 

 other respects. It is imported from the Continent, but where made 

 and from what wood we know not. Huile de Cade is mentioned by 

 Olivier de Serres,^ a celebrated French writer on agi'iculture of the 16th 

 century ; it is named by Parkinson" in 1640 ; also by Pomet,' in whose 

 time (1694) it was rarely genuine, common tar being sold in its place. 



Beech Tar — Tar is also manufactured from the wood of the beech, 

 Fagus silvatica L., and has a place in some pharmacopoeias as the best 

 source of creasote. 



Birch Tar — is made to a small extent in Russia, where it is called 

 Dagget, from the wood of Betulii alba L. It contains an abundance of 

 pyrocatechin, and is esteemed on account of its peculiar odour well 

 known in the Russia leather. A purified oil of birch tar is sold by the 

 Leipzig distillers. 



PIX NIGRA. 



Pix sicca vel solida vel navalis ; Pitch, Black Pitch ; F. Poix noire ; 

 G. Schiffspech, Schusterpech, Schivarzes Pech. 



Botanical Origin — see Pix liquida. 



Production — When the crude products of the dry distillation of 

 pine wood, as described in the previous article, are submitted to re-dis- 

 tillation, the following results are obtained. The first 10 to 15 per cent, 

 of volatile matter consists chiefly of methylic alcohol and acetone. A 

 higher temperature causes the vaporization of the acetic acid, while the 

 still retains the tar. This last, subjected to a further distillation, may 

 be separated into a liquid portion called Oil of Tar (OleuTn Picis 

 liquidce), and a residuum which, on cooling, hardens and forms the 



^ Thidtre (TAfjriculture, Paris, 1600. 941. ^ Hist, des Ihofftus, Paris, 1694. part i. 



- Theatrum Botanicum, 1033. chap. xii. xiv. 



