30 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. 



solution of caustic soda or with baryta-water, yielding a salt of the 

 acid, and the alcohol corresponding to the basic radical contained 

 in them. This latter body may be separated by distillation. 1 

 Acetate of octyl, which occurs in the oil of Heracleum, would 

 thus yield an acetate and octyl alcohol. Certain substitution 

 acids, such as methyl-salicylic acid, might be similarly decom- 

 posed; this, for instance, would yield a salicylate and methylic 

 alcohol. The latter class of compounds would split up on treat- 

 ment with hydriodic acid ; methyl-salicylic acid would thus yield 

 iodide of methyl and salicylic acid. 



If the alcohols and iodides thus* liberated are tolerably freely 

 soluble in water, and therefore not mechanically separable, they 

 must be removed by fractional distillation, in which chloride of 

 calcium and other hygroscopic substances may be often used with 

 success. 2 Their identification should rest upon the determination 

 of boiling-point and vapour-density, and the ultimate analysis. 

 The same applies in the case of an ethereal oil containing an 

 .alcohol a priori. 



Of the alcohols that may be more commonly separated from 

 ethereal oils, methyl alcohol boils at 58 '6, ethyl at 78*4, propyl at 

 96, isopropyl at 83 to 84, butyl at 116, isobutyl at 109, amyl 

 at 130, pseudo-amyl at 120, hexyl at 157, heptyl 175 '5 to 

 177-5, octyl at 196 to 197. 



To distinguish between a primary, secondary, and tertiary 

 alcohol, V. Meyer and Locher recommend conversion into iodide. 

 This is mixed with twice its weight of nitrate of silver and a little 

 sand, and distilled, the distillate shaken with strong solution of 

 caustic potash and nitrite of potassium, and then acidified with 

 dilute sulphuric acid. If a primary alcohol is present the mixture 

 will turn red, if a secondary, blue (which may be removed by 

 shaking with chloroform), whilst tertiary alcohols give colourless 

 products of decomposition. In the series of secondary alcohols 

 the reaction succeeds as far as amyl alcohol, in the series of primary 

 alcohols as far as octyl alcohol (Gutknecht). 3 



The acids separated from the ethereal salts, obtained by decom- 

 posing the alkali or barium salt with sulphuric or phosphoric acid, 

 may be examined according to the directions given in 25, 34, 130. 



1 Cf. Wanklyn, Chem. News. xxvi. 134. 



2 If the ethereal salt yield ethylic alcohol as a product of decomposition, 

 the amount may be directly estimated from the specific gravity of the distillate. 



3 See also Heil and Urech, Ber. d. d. chem. Ges. xv. 1249 (1882). 



