--------------------------------------------------------------------- Glyceride. | Melting | Refractive | Saponification | Point, deg.C. | Index at 60 deg. C. | Equivalent. --------------------------------------------------------------------- Butyrin | Liquid at -60 | 1.42015 | 100.7 --------------------------------------------------------------------- Isovalerin | ... | ... | 114.7 --------------------------------------------------------------------- Caproin | -25 | 1.42715 | 128.7 --------------------------------------------------------------------- Caprylin | -8.3 | 1.43316 | 156.7 --------------------------------------------------------------------- Caprin | 31.1 | 1.43697 | 184.7 --------------------------------------------------------------------- Laurin | 45 | 1.44039 | 212.7 --------------------------------------------------------------------- Myristin | 56.5 | 1.44285 | 240.7 --------------------------------------------------------------------- Palmitin | 63-64 | ... | 268.7 --------------------------------------------------------------------- Stearin | 71.6 | ... | 296.7 --------------------------------------------------------------------- Olein | Solidifies at -6 | ... | 294.7 --------------------------------------------------------------------- Ricinolein | ... | ... | 310.7 --------------------------------------------------------------------- Of the above the most important from a soap-maker's point of view are stearin, palmitin, olein and laurin, as these predominate in the fats and oils generally used in that industry. The presence of stearin and palmitin, which are solid at the ordinary temperature, gives firmness to a fat; the greater the percentage present, the harder the fat and the higher will be the melting point, hence tallows and palm oils are solid, firm fats. Where olein, which is liquid, is the chief constituent, we have softer fats, such as lard, and liquid oils, as almond, olive and cotton-seed. _Stearin_ (Tristearin) can be prepared from tallow by crystallisation from a solution in ether, forming small crystals which have a bright pearly lustre. The melting point of stearin appears to undergo changes and suggests the existence of distinct modifications. When heated to 55 deg. C. stearin liquefies; with increase of temperature it becomes solid, and again becomes liquid at 71.6 deg. C. If this liquid be further heated to 76 deg. C., and allowed to cool, it will not solidify until 55 deg. C. is reached, but if the liquid at 71.6 deg. C. be allowed to cool, solidification will occur at 70 deg. C.