Black, Lamp′

Syn. Fuli′go lucer′næ , F. pi′nea , ., L.; Noir de fumée , ., Fr.; Kienru , ., Ger. Prep. 1. (On the small scale.) A conical funnel of tin-plate furnished with a small pipe to convey the fumes from the apartment, is suspended over a lamp fed with oil, tallow, coal-tar, or crude naphtha, the wick being large and so arranged as to burn with a full smoky flame. Large spongy, mushroom-like concretions of an exceedingly light, very black, carbonaceous matter, gradually form at the summit of the cone, and must be collected from time to time. The funnel should be united to the smoke-pipe by means of wire, and no solder should be used for the joints of either. 2. ( Commercial. ) On the large scale, lamp-black is now generally made by burning bone-oil (previously freed from its ammonia), or common coal-tar, and receiving the smoke in a suitable chamber. In the patented proce of Me rs Martin and Grafton the coal-tar is violently agitated with lime-water until the two are well mixed, after which it is allowed to subside, and the lime-water having been drawn off, the tar is washed several times with hot water. After subsidence and decantation it is put into stills, and rectified. The crude naphtha in the receiver is then put into a long cast-iron tube furnished with numerous large burners, underneath which is a furnace to heat the pipe to nearly the boiling point. Over each burner is a sort of funnel which goes into a cast-iron pipe or main, which thus receives the smoke from all the burners. From this main the smoke is conveyed by large pipes to a succe ion of boxes or chambers, and thence into a series of large canvas bags arranged side by side, and connected together at top and bottom alternately. Fifty to eighty of these ‘bags’ are employed; the last one being left open to admit of the escape of the smoke, which has thus been made to traverse a space of about 400 yards. As soon as the bags contain any considerable quantity of black they are removed and emptied. The black deposited in the last bag is the finest and best, and it becomes progre ively coarse as it approaches the furnace. Obs. The state of minute division in which the carbon exists in good lamp-black is such as cannot be given to any other matter, not even by grinding it on porphyry, or by ‘elutriation’ or ‘washing over’ with water. On this account it goes a great way in every kind of painting. It may be rendered drier and le oily by gentle calcination in close ve els, when it is called burnt lamp-black, and may then be used as a water-colour; or its greasine may be removed by the alkali-treatment noticed under Indian ink. It is the basis of Indian ink, printer’s ink, and most black paints. deal. It is objectionable chiefly from being liable to take fire spontaneously when left for some time moistened with oil.