Dr. Fownes on the Preparation of JEther. 387 



liquid in such quantity as to maintain at once an invariable tem- 

 perature and rapid and violent ebullition. It was soon found that 

 by a little management the thermometer could be kept quite sta- 

 tionary at any required point within the limits before referred to. 

 At 300°, and thence to 360°, the separation of the distilled products 

 into two strata was very distinct and beautiful ; at 280° to 290°, 

 enough alcohol passed over unchanged to prevent this separation 

 until a little water had been added. There was a slight trace of 

 sulphurous acid, and the mixture in the flask gradually deepened in 

 colour, until at last it became nearly black, without however in the 

 slightest degree losing its efficiency. 



At this period the process had been kept up about fifteen hours ; 

 more than a gallon of alcohol — twenty times the weight of the acid — 

 had passed through the apparatus, and as the activity of the opera- 

 tion remained to the last unimpaired, it seems fair to infer that its 

 only limits are the loss of sulphuric acid by volatilization, and the 

 formation, in small quantities, of secondary products, such as oil of 

 wine, sulphurous acid, and defiant gas. 



The sether obtained was mixed with some caustic potash and rec- 

 tified by the heat of warm water; its sp. gr. at 60° was *730, and 

 it measured fully three pints. As merely water at 55° was used for 

 condensation in place of ice, much loss of vapour must have oc- 

 curred ; and since the residual alkaline liquid yielded a large quan- 

 tity of alcohol by distillation, the process must be considered on the 

 whole a tolerably productive one, although still very far from what 

 might be desired. Of course, on a large scale much of this loss 

 would be avoided. 



It was remarked that during the whole of the operation, even 

 when the temperature was purposely kept so low as to allow much 

 alcohol to escape decomposition, a considerable quantity of perma- 

 nent gas made its appearance. By adapting to the lower end of the 

 worm of the condenser a two-necked receiver furnished with a bent 

 tube dipping under water, it was easy to collect and examine this 

 gaseous matter. When purified from aether-vapour by washing with 

 oil of vitriol, it was inflammable, burned with much light, and pos- 

 sessed the peculiar alliaceous odour characteristic of purified defiant 

 gas. Its production became much increased by a rise of tempera- 

 ture ; at 310° it passed in a rapid succession of large bubbles. 



There appears no difficulty then in applying Mitscherlich's con- 

 tinuous process to the economical manufacture of sether on the great 

 scale ; it is very probable too, that by avoiding the use of a naked 

 fire much of the secondary action to which allusion has been made 

 might be prevented, while by a proper condensing arrangement the 

 waste obvious in my own experiments would be avoided. The most 

 advantageous temperature could be determined by experience in a 

 very short time, and with this knowledge the process might be con- 

 ducted ever afterwards in such a manner as to yield a perfectly uni- 

 form product. A somewhat low temperature, about 280° to 290°, 

 might possibly be the most advantageous, since it would be better 

 to let a little alcohol escape setherification, than to use heat enough 



2C2 



