Salts of the alkyl radicals are as a rule volatile ; they are produced by distilling the alcohols with the respective acid. Ethyl nitrite, for example, is formed by distilling a mixture of alcohol, sodium nitrite, and sulphuric acid : NaNO2 + H2SO4. Aq + C2H5OH = C2H5NO2 + NaHSO4.Aq. It is a volatile liquid, with a pleasant odour, which, when boiled with potash, is hydrolysed, with formation of sodium nitrite and ethyl alcohol: C9H5NO2 + KOH.Aq = K-0-N=O.Aq + C2H5OH. The nitrate, C2H5ONO2, cannot be prepared from nitric acid and alcohol unless the presence of nitric peroxide is excluded; for this purpose urea, CO (NH0)9, is added in small proportion to the mixture ; its presence prevents the oxidation of the alcohol, and brings about the normal action C2H5OH + HNO3 = C2H5NO3 + H9O. The nitrate resembles the nitrite in properties. On mixing alcohol with sulphuric acid there is a considerable rise in temperature, and hydrogen ethyl sulphate is produced : C2H5O H + HO-SO2-OH = HO-SO2~OC2H5 + H2O. A considerable excess of sulphuric acid must be present in

1 The Roman figures represent the 11 valency" of the metal, i.e. the number of electrons which it loses on going into solution as an ion.

order to ensure the nearly complete conversion of the alcohol into the ethyl salt. To remove this excess, calcium carbonate is added, which forms sulphate of calcium and a double sulphate of ethyl and calcium, Ca(C2H5SO4)2 ; the former is nearly insoluble in writer, while the latter is readily soluble ; from the calcium salt the acid may be produced by addition of the theoretical amount of sulphuric acid. On evaporation it is a syrupy liquid ; it decomposes when heated into ethylene, sulphur dioxide, carbon monoxide, and carbon dioxide. As seen by the formula of the calcium salt, the acid is a monobasic one. The potassium salt, for example, has the formula K(C9H5)SO4; the salts are all soluble. Similar acids are formed from other alkyl radicals, such as methyl, amyl, etc.