100 



UNDULATORY FORCES. LIG 1IT. 



[VOLATILE OILS. 



excellent oil, called thfrtha, in expressed from several 

 upocioa of rinapii, as the torio, glauca, m'./. A-.-. All 

 those varieties of mustard oil are very dark-coloured 

 when first expressed, and they have the peculiar pungent 



:r of mustard. Both of these properties are, how- 

 ever, removed by the process of refining; and then the 

 oil may be used in the place of rape or colza for illu- 

 minating purposes. Usually the oil is employed for the 

 adulteration of the 1.. 



(<>. ) Besides these oils, many others are employed in 

 various parts of the world, for the purpose of giving 

 light; thus, the oil of plum-stones (Prunus domestics), 

 and of raisin-stones, or wine-stones (fit is rim/era), are 

 used in Spain, Germany, and France. The oils of bella- 

 donna-seed (Atri><i belladtmna), tobacco-seed (Nicotiana 

 tabacwn et nuticum), and henbane-seed (Hyoscyamut 

 niytr), are used in Swabia and Wurtemberg. Oils are 

 also extracted from the beech-nut (Fagus sylvatica), 

 Kunllower-seed (Helianthut annuus), weld-seed (Reseda 



'-(), orange seed (Citnis aurantium), cucumber-seed 



irtnta pepo), <tc. ; and in India there are mini' 

 plants, which yield abundance of oil that is well suited 

 for illuminating purposes. Among these may be men- 

 tioned ramlil oU, or, as it is sometimes named, teal oil, 

 from several varieties of Gurzotia, as Gurzotia oleifera 

 and Abyssinica, both of which yield about eighty-four 

 per cent, of oil that is very similar to scssamum oil ; 

 Poon-teed oil, or Pinnacottay oil, from the seeds of 

 Calophyllum inophyllum, which furnish about sixty per 

 cent, of it ; Napala oil, from the seeds of Jatropha 

 curcat; Mulu unnay oil, from the seeds of Argemone 

 ifexicana ; Clteeroojee oil, from the fruit of Chirongia 

 stipida, or Buchanania latifolia ; oil of Kossumba, or 

 Koosm oil, from the seeds of the safflower (Carthamus 



riiis), which yield about twenty-eight per cent, of 

 it; Kaiutgit nune, or Kurrunj oil, from the seeds of 

 Pongamia glaljra, or Galedupa arborea; Mooncela oil, 

 from the seeds of Dolichos biftorus(f); Caju apple oil, 

 from the seeds of Anacardium occidentals ; Lambolee oil, 

 from the seeds of Bergera koenigii ; common jungle oil, 

 from the seeds of Ricmus communis ; and several other 

 varieties, the sources of which are not well known. jSIany 

 of these oils are admirably well suited for combustion 

 in lamps ; and, if there were a sufficient demand for them, 

 they might be furnished to commerce in considerable 

 quantity. "The knowledge of this circumstance," say 

 the jurors, in their report on the products of the Great 

 Exhibition, "is of great practical value, because, not 

 only is it possible that by the introduction of improved 

 machinery, or by increased facilities of conveyance, their 

 price may be reduced; but the very existence of such 

 substances tends to equalise the market value of those 

 oils now generally employed. And should, at any time, 

 accidental circumstances cause the price of the latter to 

 advance, these substances would then be most advan- 

 tageously introduced, and would, probably, ere long, 

 altogether supersede the oils in the place of which they 

 had been originally imported." 



Volatile Ottt. (a.) OH of turpentine, or camphine, may 

 be obtained from the oleo-resinous exudation of various 

 species of pine, larch, <tc. , as the Scotch fir (Pinus syl- 

 vestru), the cluster pine of Bordeaux (Pinus pinaster), 

 the swamp pint' of America (Ptnu palustris), the frankin- 

 cense pine of Virginia (Pinui taeda), the silver fir of 

 Germany, Siberia, and Switzerland (Abies picea), the 

 roniiiioii larch of the continent (Larix Europ&a), and 

 tin' mi Dentine pistacia of Syria and Greece (Pustacia 

 trri'biiitlmt). The olbo- resin is imported into this country 

 iiniler the names of common turpentine, Bordeaux tur- 

 pentine, Strasburg turpentine, and Venice turpentine. 

 The first of these yields the great bulk of the turpentine 

 of commerce ; it is the produce of the Pinus pain 

 and perhaps, also, of the Pinus tttda, and is chiefly 

 import**! from the United States of America. The 

 method which is generally adopted for procuring this 

 oleo-resin in tut follows: The tree is selected, and a 

 hollow is cut into it, a few inches from the ground ; the 

 bark U then removed for a space of eighteen or twenty 

 niche* above the hollow; and for several months 



namely, from March to October the turpentine (lows 

 from the divided s.i into the excavation. At 



uifiit times the semi-fluid matter is scooped out, 

 and put into casks ; and, when these are full, they are 

 Bent away for exportation. 



Volatile oil of turpentine is procured from the oleo- 

 resiu by distilling the latter with a due proportion of 

 water. The turpentine and water come over together, 

 forming a milky liquor, which, on standing, separates 

 into two layers, of which the turpentine is the upper- 

 most. These are easily decanted or poured off one from 

 the other ; that which remains in the still is resin. 

 Common American turpentine yields from fourteen to 

 of spirits. 



The turpentine which is thus obtained is not suffi- 

 ciently pure for combustion in the camphine lamp, for it 

 contains a small proportion of resin, which is very apt 

 to clog the wick. This impurity is easily removed by 

 a second distillation, and the product which is thus 

 obtained is sent into commerce under the name of 

 camphine. It is a colourless, limpid, and very in- 

 flammable liquid, that burns with a remarkably sooty 

 flame. Its specific gravity is 870, and it boils at a 

 temperature of 314 Fah. ; though, if water bo present, 

 it will distil at as low a temperature as 212. Tur- 

 pentine freely absorbs oxygen from the air, and is con- 

 verted into an oleo-resin. In the course of four mouths 

 it will take in about twenty times its bulk of atmospheric 

 oxygen. The change which is thus produced in the 

 liquid, renders it unfit for combustion in the camphiuo 

 lamp, in consequence of the resinous oxide having a 

 tendency to clog the wick. To remedy this evil, the 

 liquid must be redistilled, and the camphine should bo 

 preserved in well-corked vessels. 



The light that is emitted from turpentine when it is 

 properly burnt, is remarkably vivid and white; in fact, 

 the illuminating power of camphine is nearly twice as 

 great as that of sperm oil ; and if it wore not for tho 

 Lability of the combustible to evolve smoke, it would be 

 one of the most valuable of all illuminating agents. 

 This, indeed, is the great objection to its use ; for it is 

 found that the slightest mismanagement of tho flame 

 causes the production of a cloud of blacks, which settle 

 upon the furniture and dress, and damage them irre- 

 parably. To obviate this as far as possible, tho chimney 

 of the camphine lamp is made very tall, and thus a 

 strong current of atmospheric air is secured to the flame. 



A mixture of turpentine and alcohol has been used 

 in France for some time past, under the name of 

 " Eclairage au Gaz Liquide." The lump which is em- 

 ployed for the combustion of this material, was originally 

 contrived by Liidersdorff; it is called a vapour-lamp, 

 because it is constructed so as to convert the volatile 

 liquid into vapour, wliich burns as it escapes through a 

 number of fine orifices. By diluting the turpentine with 

 alcohol, its liability to smoke is considerably diminished ; 

 but still there is a large quantity of soot evolved when 

 the mixture is burnt in an open lamp without a glass. 

 The French liquid has a very peculiar odour ; it is clear 

 anil limpid like water, and has a density of 823. Its 

 boiling point is 190 Fah. When mixed with water, it 

 becomes turbid and milky from the separation of tho 

 turpentine, which soon floats to the surface and forms an 

 oily layer, the bulk of which is about half that of tho 

 original liquid. From this it would appear that it con- 

 sists of about equal parts of strong alcohol and tur- 

 pentine, tho mixture being doubtless effected by distilling 

 the two liquids together ; for if alcohol and tur- 

 pentine are merely shaken up together, they will not 

 unite in this proportion : indeed, 100 parts of spirits of 

 wini), of specific gravity 840, will only take up ]:>', of 

 turpentine ; and alcohol of much less density (830) will 

 not take up more than 20 per cent, of it. 



When the French liquid is burnt in an ordinary open 

 lamp, at the rate of 138 grains per hour, it gives a light 

 which is about two-thirds as great as that of a standard 

 Hperm candle. 



The great objection to the use of this liquid is its 

 liability to explode when its vapour becomes mixed with 



