ELECTROSYXTHESIS. 309 



discharged at the anode, leaving an uncharged residue 

 which combines with a similar one from a neighbouring 

 ion, thus — 



COOEt COOEt COOEt COOEt 



CH- +-CH = CH CH 



COOEt COOEt COOEt COOEt 



precisely as in the iodine synthesis. 



As the sodium compounds of malonic ether and similar 

 bodies are decomposed by water, it is necessary to conduct 

 the electrolysis in alcoholic solution. The resistance of 

 such a solution is very high, so that the current used by 

 Mulliken did not exceed 0*3 amperes, the rate of produc- 

 tion of the synthetic product being therefore in this case 

 very slow. 



In the aqueous solutions employed by Crum Brown 

 and Walker, the current may be easily allowed to rise to 

 5 amperes in an ordinary platinum crucible if adequate 

 cooling arrangements are provided, so that several hun- 

 dred grams of ethereal products may be obtained even 

 with a single apparatus in the course of a day or two's 

 work. The yield is very satisfactory, reaching in ordinary 

 practice to over half that theoretically possible. This 

 method of electrosynthesis is by no means yet exhausted 

 and will doubtless yield interesting results in the future. 



Thus far we have used the term synthesis in the sense 

 usually adopted by organic chemistry, namely, to express 

 the linking together of carbon atoms which were originally 

 separate from each other. In a more extended sense the 

 term may be employed to denote the linking together of 

 any two similar atoms. Thus corresponding with the 

 synthetic action of iodine on the sodium salt of a carbon 

 compound, alluded to on p. 308, we have a precisely ana- 

 logous action of iodine on the sodium salt of a sulphur 

 acid, two sulphur atoms being thereby linked together 

 which originally belonged to different molecules. Sodium 

 thiosulphate NaOSO.'SNa, is acted upon by iodine with 



