70 



CHEMISTRY. 



Klementt 

 Chemutry. 



C<>mpoi- 

 tidn. 



Acetic 

 Mher. 



Hpwob- 

 ( aincd. 



lit proper- 

 tie*. 



riunphoric 



'il.tr. 



How ob- 

 tained. 



muriatic acid is disengaged during; the combustion. 

 Thus it appears that muriatic acid is one of its con- 

 stituents. But as the presence of that acid cannot 

 be detected before combustion by the usual tests, it 

 is obviously neutralized by the other constituents of 

 tlie ether. Thenard has endeavoured to ascertain 

 the constituents of this ether. The following are 

 the proportions which he found : 



Muriatic acid, . . 29.44 



Carbon, 36.61 



Oxygen, 23.31 



Hydrogen, .... 10.64 



100.00 



During the formation of muriatic ether, no gas 

 whatever is evolved except the ether, and no new pro- 

 duct appears except the ether itself. A portion of 

 the muriatic acid disappears, and exactly the same 

 portion makes its appearance again when the ether is 

 burnt. These effects render it probable that muria- 

 tic ether is a combination of muriatic acid and alco- 

 hol. But if any dependence can be put in the above 

 analysis, and in Saussure's analysis of alcohol, it is 

 obvious that the alcohol in entering into the compo- 

 sition of muriatic ether has been altered, as its con- 

 stituents are not in the same proportion as in pure 

 alcohol. 



4. Acetic Ether. 



Acetic ether was discovered in 1759 by the Count 

 de Lauraguais, who obtained it by distilling a mix- 

 ture of alcohol and acetic acid. The process has 

 been often repeated, and has been improved since its 

 original discovery. Thenard has lately examined the 

 properties of this ether. 



He obtained it by distilling a mixture of strong 

 acetic acid and alcohol in a retort, and repeating the 

 distillation twelve times. No gas was found, nor any 

 symptom of the decomposition of either of the sub- 

 stances used exhibited. He then saturated the acid 

 with potash, and by distilling the liquid off acetate of 

 potash, he got the ether in a separate state. 



Acetic ether is limpid and colourless. It has an 

 agreeable odour of ether and acetic acid. It has a 

 peculiar taste, bearing no resemblance to that of 

 alcohol. It does not redden vegetable blues. At 

 the temperature of 44|, its specific gravity is 0.866. 

 It boils at the temperature of 160. It burns with 

 a yellowish white flame, and acetic acid is developed. 

 It undergoes no change by keeping. At the tem- 

 perature of 62, it requires more than seven times its 

 weight of water to dissolve it. It seems, from the 

 preceding account, to be a kind of combination of 

 acetic acid and alcohol, substances which it seems 

 have the property of neutralizing each other. 



5. Phosphoric Ether. 



From the late experiments of Boullay, it appears 

 that ether may be formed also by meant ot phos- 

 phoric acid. This acid, of the consistence of honey, 

 was put into a retort, and heated nearly to the tem- 

 perature of boiling water. Alcohol was then intro- 

 duced by means of a funnel passing to the bottom of 

 the acid, and the mixture distilled. A liquid was 

 obtained, which, when rectified off muriate of lime, 



yielded an ether posiesting all the properties of iul- Elemtmtj 

 phuric ether. 



Besides these ethen, several others have been form- 

 ed by means of other acids. Indeed, from the late 

 experiments of Thenard, there is reason to believe 

 that almost all the remaining acids may be made to 

 combine with alcohol, and to form a liquid which 

 might be denominated an ether, by distilling a mix- 

 ture of alcohol, sulphuric acid, and the acid in ques- 

 tion. 



From the preceding detail, it appears that there 

 are two kinds of ether essentially distinct : The first, 

 consisting of sulphuric and phosphoric ethers, is form- 

 ed by the decomposition of alcohol, and contains no 

 acid. All the others contain an acid, and several of 

 them seem to be combinations of an acid and alcohol. 

 Alcohol appears to have the property of neutralizing 

 acids, a property not suspected till lately ; though 

 several other vegetable substances seem to possess the 

 same property. 



SECT. III. Volatile Oils. 



The term oil is applied to a number of liquids, Volatile 

 which, when dropt upon paper, sink into it, and oil*, 

 make it semitransparent, or give it what is called a 

 greasy stain. Chemists have divided them into two 

 classes, _/(jerf and volatile. 



Volatile oils, called also essential oils, are distin- Their pro- 

 guished by the following properties : pcrtiea. 



1. Liquid, often as liquid as water; sometimes 

 viscid. 



2. Very combustible. 



3. An acrid taste and a strong fragrant odour. 



4. Volatilized at a temperature not higher than 

 212. 



5. Soluble in alcohol, and imperfectly in water. 



6. Evaporate without leaving any stain on paper. 

 Volatile oils are almost all obtained from vege- How ob- 



tables, and they exist in every part of plants except tained. 

 the cotyledons of the seed, where they have never 

 been found. They are sometimes obtained from 

 plants by simple expression. But in general they are 

 procured by mixing the vegetable substance contain- 

 ing them with water, and distilling. The oil comes 

 over along with the water, and swims on its surface 

 in the receiver. 



They are very numerous, but a detailed account 

 of each would not be interesting ; a general account 

 of their properties will be sufficient for our purpose. 



Most of them are liquid. Some indeed are as li- 

 quid as water, as oil of turpentine. Some are viscid, 

 and some of the consistence of butter, or even more 

 solid. 



Their colours are very various. Some are colourless 

 like water. Some yellow, brown, blue, green, &c. 



Their odours are so various as to defy all descrip- 

 tion. It is sufficient to say, that all the fragrance of 

 the vegetable kingdom resides in volatile oils. Their 

 taste is acrid, and sometimes they are even corrosive. 



Their specific gravity is also various. Oil of tur- 

 pentine, the lightest oil known, is 0.792, and oil of 

 sassafras, the heaviest, is 1.0<H. 



They evaporate very readily in the open air, dif- 

 fusing their fragrant odonr around. In close vessels 



