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ap=4.53 to 463 for 1 decimetre. (Specific gravity not ven; but taking it as 0.81, we get [a] =

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Bull. soc. chim. [2] 21, 542).

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5.6 to 5.7.)

Le Bel

By repeated distillation with caustic potash, and still more ickly with metallic sodium, active amyl-alcohol is rendered active. Le Bel (Bull. soc. chim. [2] 25, 545). Lævo-amyl-alcohol y repeated distillation with caustic soda becomes dextro-rotatory. + 2° for 1 decimetre according to Beignes Bakhoven (Pogg. upp. Bd. 6, 329); but this is denied by Le Bel (Bull. soc. chim. [2] 5, 199) and Balbiano (D. C. G. 1876, 1692).

D

According to Pierre and Puchot aqueous amyl-alcohol gives a tronger rotation than the anhydrous alcohol. Ley (D. C. G. 1873, 370) is, however, unable to confirm this.

DERIVATIVES OF ACTIVE AMYL-ALCOHOLS..

Active valerianic acid. Dextro-rotatory.

(a) From lævo-amyl-alcohol.

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exact determination of the specific rotation of para-lactic acid is impossible as this substance, even at ordinary temperatures, passes gradually into the ether-anhydride, C H10 O5, and into lactide, CH, O2, both of which are strongly lævo-rotatory.

4

Freshly prepared, it shows in aqueous solutions, in which the degrees of concentration were determined by titration (reckoned as CHO), the following specific rotation :

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By standing, the rotation of the solutions gradually increases. If they be then diluted with water a sudden decrease of rotation takes place, which, however, gradually increases again, but without returning to its original amount. For example, two specimens of equal concentration gave the following results :—

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The gradual increase here observed is due to the gradual conversion of the lævo-rotatory molecules of the anhydride, C. H10 05, originally present in the solution, into the dextro-rotatory molecules of the acid C, H, O3, which, moreover, is proved by the fact that, if we neutralize the liquid with alkali, it gradually recovers its acidity.

The decrease of rotatory power on the adition of water, is explained by Wislicenus to be caused by the formation of the hydrate, C, H, O3 + H2O, to which he assigns a rotatory power inferior to that of the acid itself.

6

It requires but 2 or 3 per cent. of the anhydride to be present to give the solution of lactic acid distinct lævo-rotation. But in preparations that have been long kept the amount of rotation becomes considerable. Thus, a solution which had been kept in vacuo over sulphuric acid for a year and nine months, and whose composition approximated very closely to 84 per cent. C. H10 О5 + 16 per cent. C3 H4O3, gave in alcoholic solution with c = 19-54, the specific rotation [a] = −85.9°.

Zinc para-lactate, Zn (C, H; O3)2 + 2 H2O. Lævo-rotatory.

3 5

2

The specific rotation in aqueous solution appears to increase with decrease of concentration.

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