Mr. A. H. Church on the Production of Formic JEther. 527 



and exactitude of the experiments, but cannot constitute an 

 essential diflFerence in the instruments. My claims to the right 

 of invention appear to be much stronger than those of Sir W. 

 Harris, for I have introduced changes into the electroscope of 

 Behrens and Fechner of a much more important nature than 

 those made by him in KiAnersley's thermometer, but never 

 entertained a thought of describing the improved electroscope 

 as a new instrument. 



Lastly, I have to remark, that the author's assertion that 

 Kinnersley only employed his thermometer for the illustration 

 of the mechanical force of the electrical explosion in the air is 

 completely destitute of foundation. In 1761 Kinnersley also 

 made use of his thermometer to test the amount of heat which 

 the discharge of a Leyden jar " produced in a sti'ip of wet 

 writing-paper, a wet flaxen and woollen thread, a blade of green 

 grass, a filament of green wood, a fine silver thread, a very 

 small brass wire and a strip of gilt paper." It is inconceivable 

 that Sir W. Harris did not know this, not because it stands in 

 one of my memoirs to which he has referred, but because these 

 experiments are mentioned in a classical English work, Frank- 

 lin's immortal ' Experiments and Observations,' which is cer- 

 tainly the best known and most widely diffused of all the works 

 that have ever been written on electricity. 



I have the honour to be, Gentlemen, 

 Your obedient Servant, 



Berlin, May 19, 1856. P. Riess. 



LXVII. Note on the Production of Formic jiEther. 

 Btj Arthur H. Church, F.C.S.* 



OXALOVINIC acid, C^H<^0^ experiences under certain 

 conditions a metamorphosis of considerable interest. Just 

 as oxalic acid, when heated with pumice-stone, with sand, or, as 

 recently pointed out by Berthelot, with glycerine, yields formic 

 and carbonic acids, as expressed by the following equation, — 



. C''H2 0» = C2H2 04 + 2CO^ 



so oxalovinic acid, when similarly treated, yields formiate of 

 sethyle and carbonic acid, thus : — 



C4^jj" 0« = C2^y 04H-2C02. 



Oxalovinic acid, even in the impure state in which it occurs 

 when prepared from its potash salt by the addition of an equiva- 

 lent quantity of sulphuric acid, furnishes, when heated with gly- 



* Communicated by the Author. 



