OILS 431 



O3>ONTOGRAPH. An instrument, invented by Professor Willis, to enable tho 

 millwright to draw and design, with great uniformity and precision, the teeth of 

 wheels. 



CEKTATiTTHIC ETHER, is used for flavouring wines. Lichtenberger of Bavaria 

 exhibited it so largely in 1862 that Dr. Hofman remarks : ' To judge from tho quan- 

 tities exhibited, this article would seem to be manufactured in a systematic manner, 

 and upon a very largo scale. The substance is a solid, and, according to all appear- 

 ance, a pure definite compound, the chemical investigation of which would present 

 considerable interest." 



OIL-CAKE, or OIL-SEED CAKE. After the expression of the oil, espe- 

 cially from linseed, the mass remaining is so called. It is much used for feeding 

 cattle. Our Importations of oil-seed cake have been as follow : 



Tons Tons 



1867 . . . 121,838 



1868 . . . 162,339 



1869 . . . 159,295 



1870 . . . 158,453 



1871 . . . 162,804 



1872 . . . 134,300 



OH OP VZTRZOXi is the old name of concentrated SULPHTJBIC ACID. 



OXZiS (Huiles, Fr. ; Oele, Ger.) form a class of valuable and interesting sub- 

 stances, and are divided into two great classes, viz. fixed or fatty oils, and volatile or 

 essential oils, Tho members of one class differ greatly, in nearly every respect, from 

 those of tho other class. The former are usually bland and mild to the taste ; the 

 latter hot and pungent. The term distilled, applied especially to the last class, is not 

 quite correct, since some of them aro obtained by expression, as the whole of the first 

 class may be, and commonly are. All the known fatty substances found in organic 

 bodies, without reference to their vegetable or animal origin, are, according to their 

 consistence, arranged under the chemical heads of oils, butters, and tallows. They 

 all possess the same ultimate constituents carbon, hydrogen, and generally oxygen, 

 and some few of the essential oils, sulphur also ; but, as a class, they are noted for 

 containing a large proportion of carbon, which renders them valuable as food, and as 

 sources of light. 



Oils have been known and used from the remotest ages. The olive-tree is frequently 

 mentioned by Moses ; and it appears to have been introduced into Europe at an early 

 period, probably by the Greeks. 



Mineral and coal oils are noticed under the respective heads of NAPHTHA ; PETRO- 

 LEUM ; SHALE, and MINERAL OILS, &c. 



For the present we shall only take notice of the fixed or fatty oils. These are widely 

 distributed through the organs of vegetable and animal nature. They are found in 

 the seeds of many plants, associated with mucilage, especially in those of the dicoty- 

 ledonous class, occasionally in the fleshy pulp surrounding some seeds, as the olive ; 

 also in the kernels of many fruits, as of the nut and almond tree ; and, finally, in the 

 roots, barks, and other parts of plants. In animal bodies, the oily matter occurs 

 enclosed in thin membranous cells, between the skin and the flesh, between the mus- 

 cular fibres, between the abdominal cavity in the omentum, upon the intestines, and 

 round the kidneys, and in a bony receptacle of the skull of the spermaceti whale ; 

 sometimes in special organs, as, of the beaver in the gall-bladder, or mixed in a 

 liquid state with other animal matters, as in the milk. 



Braconnot, but particularly Easpail, has shown that animal fats consist of small 

 microscopic, partly polygonal, and partly reniform particles, associated by means of 

 their containing sacs. These may be separated from each other by tearing the recent 

 fat asunder, rinsing it with water, and passing it through a sieve. The membranes 

 being thus retained, the granular particles are observed to float in tho water, and 

 afterwards to separate, like the globules of starch, in a white, pulverulent, semi- 

 crystalline form. The particles consist of a strong membranous skin, enclosing 

 stearine and elaine, or solid and liquid fat, which may be extracted by trituration and 

 pressure. These are lighter than water, but sink readily in spirit of wine. When 

 boiled in strong alcohol, the oily principle dissolves, but the fatty membrane remains. 

 These granules have different sizes and shapes in different animals : in the calf, the 

 ox, the sheep, they are polygonal, and from ^th to ^-igth of an inch in diameter ; in 

 the hog they are kidney-shaped, and from ^th to ^th f an ^ ncn * n man * ne y are 

 polygonal, and from ^th to g 5 th of an inch ; in insects they are usually spherical, 

 and not more than 5 gth of an inch. 



The fat oils are contained in that part of the seed which gives birth to the 

 cotyledons ; they are not found in the plumula and radicle. Of all the families 

 of plants the Crucifera are the richest in oleiferous seeds ; and next to these are 

 tho Drupacea, Amentacea, and Solanece. The seeds of the Gramine and Leguminoscs 

 contain rarely more than a trace of fat oil. One root alone, that of the Cyperus 



