cooled, affords white pearly crystals of valerate of zinc. The mother-water, drained from these crystals, should not yield, by further evaporation and cooling, a salt crystallizing in six-sided tables and very soluble in water" (acetate).-Valerate of barium is soluble in 2 parts cold water, sparingly soluble in alcohol; Caprylate of barium in 120 parts water, nearly insoluble in alcohol; Caprinate of barium almost insoluble in water.

Quantitative.-e. Free valeric acid, in absence of other acids, may be determined by normal volumetric solution of alkali. Weighing 10.2, the number of cub. cent. of alkali solution equals the number per cent. of HC,H,O,; weighing 12., the number of cub. cent. equals the number per cent. of HC,H,0,.н2O.

2

f. A weighed quantity of the acid (1 gram in a tared flask) should require not less than 26 times its weight of water at 16° to 18° C. for perfect solution (absence of alcohol, acetic acid, valerates, etc.), and should require not more than 30 times its weight for exact solution (absence of fatty acids, valeral, etc.)— DUFLOS.

43. Formic, Acetic, Butyric, and Valeric acids may be separated from each other by Fractional Saturation and Distillation, as follows: (This method is generally applicable in fractional distillation.)-To one-half of the material to be distilled add enough potassa or soda to neutralize, and then mix with the other half and distil-with a thermometer in the retort or generating flask to show the boiling point-receiving the dis tillate all together. If the boiling point has been constant, no farther separation can be effected by this method; if not, saturate half the distillate, mix with the remainder, and distil as before. Repeat the fractional saturation with alkali and distillation of the free acid of the receiver until the distillate has a constant boiling point. Now to the several retort residues add excess of dilute sulphuric acid and distil each; if their distillates do not show a constant boiling point, half saturate and distil, in each case, as before, until the boiling points are constant. Again

decompose and distil the retort residues, as before, repeating the operations until the whole of the organic acids is obtained in separate distillates, each showing a constant boiling point. The work may be tabulated as follows:

Fractional Saturation and Distillation.

Mixture of acids, a, b, c, d, of different boiling points.
Neutralize half the mixed acids and distil.

Saturate with sul-(Boil. pt. const'nt.) Saturate with sul- (Boil. pt. const.)

phuric acid and

distil.

IN RECEIVER: d.

(Boil.pt. const❜nt.)

phuric acid and
distil.

IN RECEIVER: b.
(Boil. pt. const❜nt.)

44. VOLATILE FAT ACIDS of the Acetic Series.

(Approaching towards these, in their properties, are the volatile acids of the acetic series which do not have a fatty consistence, though commonly termed "volatile fatty acids "-viz., FORMIC, ACETIC [PROPYLIC], BUTYRIC, and VALERIANIC acids.)

Characterized by their pungent and unpleasant odors (when free), by the persistent and fragrant odors of their ethyl ethers, by their liquid and more or less oily consistence at ordinary temperatures and their capability of distillation, by their sparing

solubility or insolubility in water and ready solubility in alcohol and in ether, by their acid reaction, by forming with alkalies salts soluble in water.

Separated from each other by Fractional Crystallization, as barium salts, as follows: Add to the mixture (aqueous or alcoholic) sufficient potassa to neutralize, and add chloride of barium to decompose. Crystallize, removing the successive crops of crystals:

The aqueous crystal-crops may be washed with hot alcoholthe washings containing the salts, successively, in order the reverse of their crystallization from alcohol. Thus, the third crop of crystals from water, when washed with alcohol, lose first caproate, then caprate and pelargonate, lastly oenanthate, with little loss of caprylate.

Separated, also, by Fractional Saturation (43).

FAT ACIDS, LIQUID AND SOLID.

45. NON-VOLATILE FAT ACIDS. Characterized by an oily consistence, leaving a permanent oil-spot upon paper, and melting at different temperatures, mostly between 14° C. and 80° C.; by insolubility in water, upon which they mostly float (in oily drops or layers, liquid if the water is hot); by free solubility in alcohol, the solutions mostly having an acid reaction, and by solubility in ether; by the (soapy) solubility of their

alkaline salts in water; by the waxy consistence of their lead salts, which melt and do not dissolve in water and have differing solubilities in alcohol and ether; by forming white, milky precipitates when their alkaline salts in water solution are treated with salts of metals not alkalies, or with acids, also when (as free acids) their alcohol solutions are diluted with water. The avidity of drying oils for oxygen is a characteristic of their acids. (See Fixed Oils.)

The nine following are some of the more frequently occurring non-volatile fat acids, placed in order of their fusibility:

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46. RICINOLEIC ACID. HC,,H,,O,. Melts at 10° to 6° C. (14° to 21° F.). Yellowish, syrupy, inodorous, of harsh and persistent taste; reddens litmus, and in alcoholic solution decomposes carbonates with effervescence; distils an illy-smelling liquid; its glyceride and all its metallic salts soluble in alcohol, its lead salt soluble in ether. When Castor Oil (ricinoleate of glyceryl) is heated on a sand-bath with a double volume of nitric acid of 25 per cent., until the nitric acid is all removed; the residue saturated with concentrated solution of sodium carbonatethe characteristic odor of œnanthyc acid is obtained.

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47. OLEIC ACID. HC,,H,,O,. Melts at 14° C. (57° F.), soft above 4° C. (39° F.) Colorless, limpid liquid of sp. gr. 0.808, odorless and tasteless, crystallizing from cold alcoholic solution in white needles; reaction neutral, becoming acid on exposure to the air, by which it finally turns brown and rancid. Its lead salt (lead plaster) is insoluble in alcohol, slowly soluble in ether (separation from palmitate, stearate, laurate, etc.) Distilled with nitric acid, all the volatile acids of the acetic series are found in the distillate.

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48. LINOLEIC ACID. HC,H,,,? Melts at about 18° C. (64° F.); faint yellow, limpid liquid of sp. gr. 0.921, of taste at first mild and afterward harsh; faintly acid to test-paper; oxidizes in the air to a thick, viscid mass, its salts, also, being changed in the air. Most of the linoleates are soluble in alcohol; the lead salt is soluble in ether.

crystallizes from alcohol in shining needles; lead salt not soluble in ether (separation from Oleic acid).

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50. LAURIC ACID. HC,,H,,O,. Melts at 43° C. (110° F.); solidifies in scales and crystallizes from alcohol in white needles; slightly acid to test-paper; lead salt sparingly soluble in alcohol, insoluble in ether.

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51. MYRISTIC ACID. HC,,H,,O,. Melts at 54° C. (129° F.); crystallizes in shining lamina; exceptional in being insoluble in ether; the alcoholic solution has an acid reaction; the lead salt is soluble in alcohol, but insoluble in ether; the barium salt nearly insoluble in alcohol.

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52. PALMITIC ACID. HC,H,,O,. Melts at 62° C. (143° F.); colorless, tasteless, odorless, showing an acid reaction; lighter than water; crystallizes, in congealing, in shining scales, from dilute solutions in slender needles; lead salt insoluble in alcohol or cold ether; barium salt sparingly soluble in water or alcohol; calcium salt insoluble in water or ether, slightly soluble in warm alcohol.

18

53. STEARIC ACID. HC,H,,O,. Melts at 70° C. (159° F.); inodorous, tasteless, colorless in liquid and white in solid state; crystallizes from alcohol in needles or nacreous scales, having the specific gravity of water; its solutions distinctly acid to testpaper; lead salt insoluble in alcohol or ether, and not wetted by water and fusible at 125° C.; barium salt insoluble in water, alcohol, or ether; magnesium salt insoluble in water, and slightly soluble in cold, more soluble in hot alcohol. [For the fusingpoints and modes of solidification of mixtures of Stearic with Lauric, Myristic, and Palmitic acids, as determined by HEINTZ, see Watts's Dictionary, v., 414.]

54. CEROTIC ACID. H.C,,H,,O,. Melts at 79° C. (174° F.) ; crystallizes in congealing in small grains, lighter than water; when pure, is capable of distillation; soluble in hot alcohol and in ether, not soluble in chloroform; solutions acid in reaction: lead salt insoluble in alcohol.