Chemical Science. 487 



alcohol both Jit common and hii^h temperatures. Coid nitric acid 

 has but Httle action upon it : hot nitric acid acts poyverfully, evolv- 

 inf^ much nitric oxide ; and the substance which separates when the 

 solution is cold, no longer has the properties of the original acid. 

 Sulphuric acid ^cts still more powerfully, decomposing the substance 

 even when cold, and when heated acting rapidly upon it, producing 

 a black solution, and changing the properties of the body altogether. 

 The action of these acids offers distinctions between this substance 

 and benzoic apid. 



If the essential oils be expqsed for a longer time to the air, there 

 occurs, at a later period than that of the formation of the acid just 

 described, another change, resulting in the production of a resinous 

 substance, and in conjunction with it» of strong acetic acid. This 

 change took place with oil of cinnamon, of mint, and others ; and 

 so much acetic acid was formed in the vessels, that not only did 

 the atmosphere redden litmus paper powerfully, but, by neutralizing 

 the acid with potash, a portion of acetate of potash was obtained. 



Upon subjecting the essential oils to a very low temperature, crys- 

 tals formed in them, and ultimately a separation of them into two 

 parts was effected, very analogous to the separation of fixed oils 

 into stearine and elaine ^nade by Chevreul. In imitation of that 

 chemist, M. Bizio has given names to the two portions into which 

 he has separated essential oils, calling the most fluid part Igruaina, 

 and the solid part Serusina. 



Igrusina is fluid at the lowest possible artificial temperature : it 

 dissolves in alcohol, evaporates when heated, and leaves no resi- 

 duum. When gradually changed by the action of oxygen, it 

 becomes denser, and ultimately is changed into resin and acetic 

 acid. 



Serusina, obtained from the oil of roses and anise, is solid at 

 60°Fahr. ; that from the oils of mint, orange, lemon, valerian, laven- 

 der, &c., require a temperature as low as 4° Fahr. for solidity. It 

 crystallizes in prismatic needles, and sometimes in plates. It is 

 soluble in alcohol, and those specimens that are solid at moderate 

 temperatures may be obtained in crystals from the alcoholic solu- 

 tion. If serusina be exposed to the air, gradual action occurs, the 

 subs^nce becomes denser and acquires a higher point of fusion, 

 and ultimately that peculiar substance appears to be formed which 

 Brugnatelli ibund in oil of turpentine. When the serusina is 

 obtained from those oils whicli jiroduce the solid acid above de- 

 scribed, it then undergoes a different change to that referred to, 

 and gives rise to the production of that peculiar acid by exposure 

 to oxygen or air. — Giornale di l^idcay ix. 360. 



27 . Change of Oil of Turpentine by. exposure to Air. — Some oil of 

 turpentine which had been exposed to air, was distilled by MM. 

 Boissenot and Perset, who obtained a very acid liquid from it, 

 which cousisted ^f acetic acid, and a substance wl^cJ^ crystallized 



