_Butyric ether_ is formed by mixing 2 parts of butyric acid with 2 parts of alcohol and 1 part of sulphuric acid. The fluid is heated to 176° F., and, after being for several hours kept at that temperature, is poured into cold water, whereby the ether separates as an oily fluid. It is then separated from the aqueous solution, washed with water to which some chalk has been added for the neutralization of the free acid, and finally the water is withdrawn from the ether by, for several days, leaving it in contact with calcium chloride. To obtain it entirely pure, it is only necessary to distil it once. It forms a clear, very mobile fluid of a pine-apple odor, and a specific gravity of 0.900. It boils at 249.8° F. Commercial butyric ether, large quantities of which are used for the preparation of the so-called _pine-apple ether_ or _essence_, is seldom pure, it being generally obtained from simply rectified butyric acid. According to another method, which is, however, not as profitable, it is obtained by distilling butter-soap with alcohol and sulphuric acid. For this purpose, bring 20 pounds of butter-soap, cut up in small pieces, into a distilling apparatus, pour over it 10 pounds of 90 per cent. alcohol and heat moderately until the soap is dissolved. Since a portion of the alcohol evaporates thereby, add 10 pounds more of alcohol and then 20 pounds of sulphuric acid. On further heating, a fluid of a very agreeable odor distils over, which is an alcoholic solution of the ethers of the volatile acids found in butter. Towards the end of the operation, in consequence of the further progress of decomposition, a development of sulphurous acid generally takes place. This is removed from the distillate by allowing it to remain for several days in contact with finely-pulverized pyrolusite (peroxide of manganese) and rectifying over burnt magnesia. In the first distillation, the heavy volatile acids of the butter remain behind; they are freed from the excess of sulphuric acid and the sulphate of sodium or potassium by washing with hot water, and can be utilized in the manufacture of soap. The butyric ether obtained from butter-soap is far from being pure butyric ether, it containing, besides it, a mixture of various kinds of ether derived from the volatile acids--caproic, capric, and caprylic acids. However, these varieties of ether possess similar properties to that of butyric acid; in alcoholic solutions their taste and odor are nearly alike, and hence can be employed in this mixture for the preparation of essences of an agreeable odor and taste.