The present limits ef the distrihution of living copaliferous trees by no means preacribe the area of the extinct forests whiell have been the source of the fossil copal. This is " crowed '' or dug up by the coast clana and the barbarians of the maritime region. In places, it is found when sinking piles for huts: and at times, it is picked up in spots overflowed by the high tides. Burton says that the E. African seaboard, from Ras Gomani in S. Int. to Ras Delg,ado in 10° 41', with a inedinin depth of 30 miles, may be called the "copal coast," every part contributing more or less to the commercial supply. He affi11118 that even a s«.tion of thia line, from the month of the Pangani River to Ngao (Monglion), would, if properly exploited, suffice for all needs. The foasil resin ia a great staple of the diatriet traversed by the newly-made rond from Dar-es-Salaarn, through the Wazamaro country, it exists, even in the richest diggings, only in patches, as though it had been produced by isolated trees. The natives work it nowhei e syatematically ; they siuk numerous test-holes and work those only which alight immediately up in the resin, abandoniog many where diligent search weuld probably be remunerative. The resin usually oceurs in red sandy soil ; according te the Arabs, the redder the aoil the better is the copal. The surface of the. copal ground ia generally a thin eoat of white aand, covering a dark, fertile humus, the vestiges of decayed vegetation, varying from a few in. to ft. in depth. ln Zanzibar Island, tho subsoil is a atitl blue clay ; here the copal is found in the vegetable soil overlying the clay. At Saa lani, the pits are about 3 ft. deep in humus and red sandy earth; the product is not esteemed, despite the redneas of the soil.
The resin called sandarus by the Araba and Hindus, sandirusi by the Wasawahili, aud wezi by the Wanynm. It is distinguished as of two kinds by the Arahs and Africans. The new, recent, " trot.," or " raw " copal (Fa., Copal tert) is called sail,' umsiza miti, or more generally chalcari, com monly corrupted to " jackass." This is either picked from the tree, or is found, as in Zanzibar Islantl, embedded at a aliallow depth in the 100,e soil, where it has not remained long enough to iindergn any change. 'Phe living trees are nf large size, averaging 20-25 ft. to the first hranches, and :3-5 ft. in girth. The trunk is dotted with exudations of the raw resin, and, 130 een the bark and the wood, are frequent secretions of the resin in a liquid form. Wh. rever ae injury has been inflicted on the tree, there au accumulation of resin will be found; when the exudation is large, it frills off and becomes covered by the duaty soil. All parts of the tree are impregnated with the resin, even extending to the fruit-pods, which contain numerous little warta or verrucesitiea of clear, colourleas resin, covered by a thin epidermis. The chahazi copal is a soft mass, of smoky appearance and low value. It ia sent to Bombay for the Indian and Chineae markets, where it is used for making an inferior varnish.
The true or " ripe" copal, the sandarusi proper, is exclusively fossil. Dr. Birk attributes it to the same species as now afford chakazi. it is certainly of vegetable origin. The regular and persistent
indentations and elevations ef the surface, to which the term "goose-skin " has been applied, have led to the supposition that the resin escaped in a liquid or semi-liquid state, and took impressions frorn the aancl in which it was deposited. This view is douhly erroneous. The impressions are due, not to sand, but to the structure of the cellular tissue of the tree; and their occurrence ia accounted for by the fact that the secretion of the resin increases with the decay of the tree, and is much hastened by the attaeks of ants and other destruetive influences, thus it is chiefly formed in maases withiu the tree itself, and naturally takes impressions from the tissue of the surrounding wood. This occurs with the existing trees. After the complete decay and destruction of the trees, the imperishable lumpa of resin have become buried in the sands which have encroached upon the fertile soil formerly occupied by the forest. The fossil reain when firat dug up has uo trace of the goose-skin upon it. It is hidden by the outer layer of the resio, which has undergone oxidation or aome molecular change during its long burial ; on removing this outer layer by an alkaline solution and the goose-skin becomes apparent.
The native method of collecting the fossil resin is to " crow " a hole about 6 in. diam. with a pointed stick, and scrape out the loosened earth by the hand aa far as the arrn will reach. Each man could easily gather 10-121b. daily, but the average is about 1 lb. The digging is carried on only during the kossi, or rainy monsoon ; during the dry season, the hardness of the ground is too great for the native implemeuts to cope with, and the resin is said to be at that time very brittle and covered with sand. The collectors do not hesitate to add much of the inferior chakazi to the sandarusi when opportunity arises. The copal gathered in Zanzibar Island is entirely chakari. That of Saadani is dull-white, and considered little better than chahazi. That obtained on the line inland from Bagamoyo and Kaole, as far as Mubonyera, though not first-rate, is much superior to that from about Saadani. Good copal is dug in the vicinity of Mbuamaji, and the diggings are said to extend for six marches inland. The Wadenkereko, a wild tribe mixed with and stretching S. of the Wazaramo, at two days' journey from the sea, supply a mixed quality, oftener white than red ; the best is procured from Hunda and tbe adjacent districts. The banks of the Rufiji River, especially the N. district of Wandd, supply the fineat and best copal; it is dug by the Wawande tribe, who either carry it to Kikunya and other ports, or sell it to travelling hucksters. In the vicinity of Kilwa, 4 marches inland, copal is dug by the Mandandu and other tribes. The produce of Ngao (Mongbou) and the Lindi creek is much cheaper than that of Kilwa, being of variable quality, mostly a dull-white chakazi. The island of Madagascar is aaid to produce both chakazi and sanchirwi identical with those of the mainland ; but little is known of the method of collecting, or of the precise quality. The species is called T. verrucosum.