374 HEINRICH ROSE ON ^THERIFICATION. 



bine to form alcohol; for it is produced only in this way when a 

 solution of pure sulphovinic acid is boiled with much water, or 

 compound aethers decomposed by water or by the hydrates of 

 bases. 



When, however, from the tendency of the hydi'ate of sul- 

 phuric acid to take up more water, aether has been evolved from 

 a mixture of alcohol and sulphuric acid, it does not take up 

 any water after being once separated : but water may be di- 

 stilled over by heating the diluted sulphuric acid. We know 

 that when ajther is treated with water, or even dissolved in it, 

 no alcohol is formed. When tether is once separated from a 

 compound of oxide of aethyl, the former can in no way be con- 

 verted by water into alcohol. Only when, as above observed, 

 the aether comes in contact with water at the moment of its ex- 

 pulsion does it form alcohol with it. The cotemporaneous dis- 

 engagement of aether and water, from a boiling mixture of al- 

 cohol and the hydrate of sulphuric acid, shows therefore quite 

 evidently that both owe their origin to two distinct processes. 



Moreover, it is by no means an anomalous phaenomenon that 

 a base, which is capable of forming a hydrate, does not combine 

 with water when brought into contact with it in a pure state : 

 great number of cases of this kind occur in inorganic chemistry. 

 We need only compare aether with that numerous class of ig- 

 nited oxides in which so compact a state of cohesion is pro- 

 duced by heat, that they not only withstand the action of water, 

 but even entirely or partially that of acids, to find abundant 

 proof of such analogies. The ignited oxides with these pro-' 

 perties always belong to the weaker bases, under which aether 

 must incontrovertibly be classed. iEther may be assimilated to 

 these oxides the more, as it like them combines directly with 

 acids with difficulty. 



But even among the stronger bases we find some whose 

 relations to water resemble those of aether. When oxide oi 

 copper is precipitated in the cold by bases from solutions ol 

 salts of the oxides of copper, it appears as hydrate of the 

 oxide of copper ; which, however, on being heated under water, 

 loses its water, and does not take it up again when left in con- 

 tact with it at a higher, or at the common temperature. 



To find out at what period, in the preparation of aether by 

 boiling a mixture of alcohol and sulphuric acid, water com- 

 mences to pass over, M. Wittstock, at my request, instituted a 



