FUEL 297 



for market. The uils of iciiileryreen (Fig. 147), marjoram 

 (Fig. 137), coriander (Fig. 14.3), thijriie (Fig. 134), caraway 

 (Fig. 140), and manj' others are tlm.s us(>(I to a greater or less 

 e.xtent. 



These same volatile oils enter also intfj the manufacture 

 of perfumer!/; ainl for this purj^jse many other volatile oils 

 are more or less in demand, as, for example, the oils of nutmeg 

 (Fig. 129), allspice (Fig. 123), .sassafras (Fig. 160), peppermint 

 (Fig. 14(3), spearmint (Fig. 135), orange-peel and orange- 

 flowers (Fig. 106), and the oil distilled from the wood of red 

 cedar (Fig. 261). It is to the fragrant oil obtained from the 

 bark of white birch (Fig. 204) that the characteristic odor of 

 Russia leather is due. 



None but fixed oils can serve as lubricants; and of these, 

 only the non-drying ones are suitable. The vegetable lubri- 

 cants most extensively employed are (1) olive-oil, used for 

 this purpose mostlj' in southern European countries where a 

 sufficiently good quality may Ijc obtained at a low price, 

 (2) ■rape-oil from the seed of a variety of turnip grown widely 

 in northern Europe and India, and (3) cotton-seed oil used 

 largely in this country. 



As illumiruuds vegetable oils have not to-day the impor- 

 tance they had before the introduction of petroleum lamp-oil 

 and paraffin candles. Nevertheless, large ciuantities of 

 vegetable illuminants are still consumed, especially in regions 

 where mineral or animal oils arc comparatively expensive. 

 Almost all the fixed oils in common u.se for other purposes 

 have served for burning, but the non-drying oils are pref- 

 erable. Olive, peanut, and rape oils, which are all rich in 

 olein, are among the best. Palmatin, as we have seen, is an 

 important constituent of coconut-oil. This substance sepa- 

 rated from the more fluid parts of the coconut-oil and other 

 palm-oils affords an excellent material for candles. 



80. Fuel, whether as a source of heat or of power, being 

 indispensable to the carrying on of almost every industry, 

 and being also a necessity for steam-transportation, for the 

 heating of buildings, and for cooking, it is plain that civihza- 

 tion could not have developed as it has, nor could it possibly 

 go on, without this source of heat. 



