Pitch, Burgundy (Facti′′tious). Syn. Pix Burgundica factitia, L. Prep. By melting good yellow resin, 1 cwt.,with linseed oil, 1 gall., and palm oil (bright), q. s. to colour. The mixture is allowed to cool considerably, and is then pulled with the hands in the same way as lead plaster is treated; after which it is placed in ‘bladders’ or ‘stands’ for sale.
Obs. The product of the above formula is the ‘Burgundy pitch’ of the shops. The ‘pulling’ or ‘working’ destroys the translucency of the resin, and imparts to it the peculiar semi-opacity of foreign Burgundy pitch. Cold water is commonly employed to cool it down. Annotta is often substituted for palm oil as a colouring substance. The addition of some of the ‘droppings’ or ‘bottoms’ of Canada balsam, Chio turpentine, oil of juniper, &c., renders this article nearly equal to foreign pitch; but in commerce this is never attempted, the aim being only the production of a lively colour with moderate toughness. A common melting-pan and fire (if clean, and carefully managed) will succeed sufficiently, but, both for safety and convenience, steam is preferable, and on the large scale, almost indispensable. A good workman can pull and put into stands or casks about 5 cwt. daily; or from 11⁄2 cwt. to 3 cwt. in bladders, the latter quantity depending on the size of the bladders. (See above.)
Pitch, Can′ada. Syn. Hemlock gum, H. pitch. Similar to Burgundy pitch; but from the Abies canadenses, or hemlock spruce fir.
Pitch, Jews’. Asphaltum.
Pitch, Min′eral. Indurated mineral bitumen. See Asphaltum, Bitumen, &c.
PIT′COAL. Syn. Coal; Houille, Fr.; Steinkohle, Ger. This article has been truly described as the most valuable of all those mineral substances from which Great Britain derives its prosperity, and the one which may be regarded as the main support of the whole system of British production. It fuses the metals, it produces the steam which sets our machinery in motion, and, in short, it may be said to render all the resources of this country available for use.
The more important kinds of coal may be classified as follows:—1. Lignite or brown coal (see page 969).—2. Bituminous or caking coals. The most widely diffused and valuable of English coals. They are subdivided into: a. Caking coal. Splinters on heating, but the fragments then fuse together in a semi-pasty mass. The chief sources of this valuable variety of coal are the Newcastle and Wigan districts, b. Cherry coal or soft coal. Lustre very bright; does not fuse, ignites well and burns rapidly. Glasgow, Staffordshire, Derbyshire, Nottingham, Lancashire, &c. c. Splint, rough, or hard coal. Black
and glistening; does not ignite readily, but burns up to a clear hot fire. It constitutes the bulk of the great coal fields of North and South Staffordshire, and occurs in the Glasgow district, in Shropshire, Leicestershire, Warwickshire, &c. d. Cannel or parrot coal. Dense and compact, having a shelly fracture, and taking a polish like jet. Splinters in the fire, and burns clearly and brightly. Wigan and other parts of Lancashire, West Glasgow, &c. The curious deposit at Bathgate, near Edinburgh, commonly known as ‘Boghead cannel coal,’ or ‘Torbanehill mineral,’ differs considerably from the ordinary ‘cannels,’—3. Anthracite or stone-coal. The densest, hardest, and most lustrous of all kinds of pitcoal. Burns with little flame or smoke, but gives great heat. South Wales, Devonshire, &c.—4. Steam coal. Approaches nearly to anthracite. Admirably adapted for steam-vessels. South Wales, Tyne district, &c.
The quality of coal may be ascertained by either directly testing its heating power or by chemical analysis. In the investigations undertaken at the Museum of Economic Geology, under the directions of Sir H. De la Beche, and which furnished the materials for the celebrated ‘Admiralty Reports,’ three different methods were adopted for this purpose.[109] These consisted in—the determination of the quantity of water which a given weight of the coal was capable of converting into steam, the quantity of litharge which it was capable of reducing to the metallic state, and, lastly, its ultimate analysis by combustion with oxide of copper. See Organic Substances.
[109] See Watt’s ‘Dict. of Chemistry,’ vol. i, page 1033.