Specific Gravity at 15° C.Saponification Equivalent. Acidity (as Oleic Acid) Per Cent. Titre, °C.Unsaponifiable Matter Per Cent.
Pale seal oil 0.9252 289 0.947 15.5 0.8
Straw seal oil 0.9231 288 4.77 15.8 1.2
Brown seal oil 0.9253 291 16.38 16.2 1.9
Whale oil 0.9163 297 1.49 16.1 1.8
Dark whale oil 0.9284 303 12.60 21.8 2.4
Japan fish oil 0.9336 296 4.79 26 0.67
Japan fish oil 0.9325 302 10.43 28 1.55
Brown cod oil 0.9260 313 14.91 21.8 1.9
Pure herring oil 0.9353 288 11.39 21.6 1.5
Kipper oil 0.9271 297 5.14 22.7 3.25

Waste Fats.—Under this classification may be included marrow fat, skin greases, bone fats, animal grease, melted stuff from hotel and restaurant refuse, and similar fatty products. The following is a fair typical selection:—

Saponification Equivalent. Acidity (as Oleic Acid) Per Cent. Titre, °C.
Marrow fat 283.3 3.6 38.7
White skin grease 287.2 4.3 36.4
Pale skin grease 286.3 9.87 35.7
Pale bone fat 289.7 8.8 40.7
Brown bone fat 289.1 11.0 41
Brown bone fat 292 20.5 40.2
Animal grease 289.4 38.1 40.4
Melted stuff 286.3 12.8 37.7

The materials in the above class require to be carefully examined for the presence of unsaponifiable matter, lime salts and other impurities.

Fatty Acids.—We have already described the various methods of liberating fatty acids by hydrolysis or saponification.

Under this heading should also be included stearines produced by submitting distilled fat to hydraulic pressure, the distillates from e from unsaponifiable matter, cocoa-nut oleine, a bye-product from the manufacture of edible cocoa-nut butter and consisting largely of free acids, and palm-nut oleine obtained in a similar manner from palm-nut oil.

These are all available for soap-making.

Less-known Oils and Fats of Limited Use.

Shea Butter.—Shea butter is extracted from the kernels of the Bassia Parkii and exported from Africa and Eastern India. This fat is somewhat tough and sticky, and the amount of unsaponifiable matter present is sometimes considerable. Samples examined by us gave the following data:—