FUSEL OIL 521 



When it is desirable to perfectly avoid contact of air with the fused substance 

 during manipulation, a narrow crucible should be employed, and a thin and narrow 

 ring of fire-clay should be placed upon the top of the tube o, to contract its opening ; 

 the flame then closes completely over the top of the crucible, and prevents access of 

 air. A proper adjustment of gas, together with exclusion of air in this manner, 

 enables a perfectly bright surface of melted copper, or even tin, to be continuously 

 maintained, from which the images of parts above are clearly reflected. The clay 

 ring may be withdrawn by lifting the plate B. A less perfect exclusion of air may 

 bo obtained by employing a narrow crucible placed rather low down in its support. 

 A small iron dish should be placed beneath the tube L to receive any melted substance 

 that may fall. The chief conditions of success in the use of this furnace are sufficient 

 gas, a suitable degree of draught, and proper regulation of gas to air. 



Several very ingenious furnaces for use in the laboratory or assay office are fully 

 described in Watts's ' Dictionary of Chemistry.' See GAS-FURNACE. 



FUR-SKIN DRESSING. Fur-skins are usually dressed by placing them in 

 their dried state in closed tubs with a little salt butter, where they undergo a treading 

 operation with men's feet until they are sufficiently soft, and bend easily. The skins 

 if large are sewn up, the fur being turned inwards ; but if small skins, such as ermine, 

 are being dressed, they require no sewing. This sewing is preparatory to the greasing 

 with butter or lard, and is intended to protect the fur from the grease, and to promote 

 the softening in the succeeding treading operation. The skins are next wetted, and 

 their flesh is removed ; or they are fleshed. See CURRYING. They are again sub- 

 jected to treading in tubs containing sawdust, that from mahogany being preferred ; 

 and afterwards in tubs containing plaster of Paris, or whitening, sprinkled between 

 the skins. The main object of this is to remove the grease which has been used in 

 the previous processes. They are then beaten with a stick and combed ; when tho 

 dressing is completed. M. Pierre Thirion proposed to soften the skins, not by tread- 

 ing, but by beating stocks, of a construction like the fulling mill. They are next 

 sewn up, and again filled in a strong vessel, where they are forced upwards by the 

 beaters, turned over and over, and thus speedily softened. They are now fleshed, and 

 then returned to the beating stocks, and mahogany or other sawdust is sprinkled upon 

 the fur, before the beating is renewed. They are next placed in a heated barrel, 

 furnished within with radial pins for turning the goods over and over, in order that 

 they may be acted upon by various dry substances, which are thrown into the barrel, 

 and absorb the fat from the skins. Through the hollow shaft of the barrel, steam is 

 introduced, which heats the skins, softening the fat> which is then absorbed by sand, 

 flour, or any other desiccative powder. It is proper to take the skins out of the 

 barrel, from time to time, to comb them. Such as have been sufficiently acted upon 

 may then be set aside. They are lastly freed from the dust by being subjected to a 

 grated cylinder in a state of rotation, and then combed by hand. 



FUSE. See FUZE. 



FUSEES. A name given to a kind of lucifer-match which does not flame ; this 

 match is used exclusively by the smokers of tobacco. Bode of Vienna introduced 

 them. A granule of powder, made of the same composition as the ordinary lucifer 

 match, is placed at the end of a match, and a mixture of charcoal and nitrate of 

 potash surrounds it. The granule is ignited by friction, and this fires the other mix- 

 ture, which burns like quick-match. 



FUSE!* OIIi. During the rectification of corn or grape spirits there is always 

 separated a fiery foetid oil of nauseous odour and taste. It is this substance which 

 is the cause of the Unpleasant effects which are produced upon most persons by even a 

 small quantity of insufficiently-rectified whiskey or brandy. Any spirit which pro- 

 duces milkiness on the addition of four or five times its volume of water may be sus- 

 pected to contain it. By repeated rectification every trace may be removed. 



Fusel oil invariably consists of one or more homologues of the vinic alcohol, C 4 H 6 2 

 (C 2 H 6 O), mixed with variable quantities of the latter substance and water. The 

 nature of fusel oil varies much with the source from whence it is obtained. That 

 which is ordinarily sold in this country for the purpose of yielding pear essence 

 consists mainly of the amylic alcohol, C 10 H 12 2 (C 5 H 12 O), mixed with from one-fourth 

 to one-fifth of spirit of wine. 



The progress of organic chemistry has been greatly assisted by the researches which 

 have been made upon fusel oil, almost all the amylic compounds hitherto obtained 

 having been directly or indirectly obtained from it. 



To obtain fusel oil in a state of purity it is necessary, in the first place, to rectify 

 it fractionally. By this means it will be found that much alcohol can be removed at 

 once. If a great quantity of water and very little vinic alcohol be present, the simplest 

 mode of purification is to shake it with water, by which means common alcohol is 

 removed in solution, while tho araylic alcohol, owing to its comparative insolubility, 



