Mr. Conneli on the Nature of Lampic Acid. 517 



cury lampic acid is changed into acetic acid. If lampic acid 

 consists of formic acid with a little acetic acid, it will not re- 

 quire any argument to show that in reducing metallic salts it 

 is not changed into the last of these acids. In concluding 

 that it was so changed, M. Liebig referred to an experiment 

 described by Mr. Daniell, that when it is heated with peroxide 

 of mercury, a shining micaceous salt is deposited on cooling, 

 which he considered to be acetate of. mercury. This experi- 

 ment I had repeatedly made, and described in my former no- 

 tice ; and my impression also then was that the precipitated 

 salt was entirely acetate of mercury; but the conclusion 

 which both Professor Daniell and myself had drawn from the 

 experiment was, not that lampic acid had been changed into 

 acetic acid, but that the acetic acid thus supposed to combine 

 with protoxide of mercury existed ready formed in the liquid. 

 From the researches which I have since made, I entertain 

 no doubt that the salt thus precipitated is to a great extent 

 formate of mercury. It undoubtedly contains in the form of 

 acetate all the acetic acid which is present in the liquid ; but 

 the fact which was formerly overlooked, is that pure formic 

 acid when heated with peroxide of mercury affords on cooling 

 a silvery micaceous salt much resembling acetate of mercury. 

 This fact is not new to chemists * ; and it was further verified 

 as follows. Crystallized formate of lead prepared with formic 

 acid obtained by Doebereiner's process from tartaric acid, was 

 heated with alcohol to take up any acetate of lead which might 

 by possibility have been present, and was then distilled with half 

 its weight of sulphuric acid diluted with an equal weight of 

 water. A portion of the formic acid thus obtained was gently 

 heated with peroxide of mercury; effervescence ensued, and 

 on cooling a micaceous shining mass like acetate of mercury 

 was deposited. When this mass was further strongly heated, 

 it was reduced to metallic mercury with effervescence. It 

 was formerly stated that when the white salt which precipi- 

 tates on cooling, after lampic acid has been moderately heated 

 with peroxide of mercury, is further strongly heated, it is in 

 like manner reduced to metallic mercury with effervescence. 



To ascertain with still greater precision the nature of this 

 salt as produced from lampic acid, a portion of it was distilled 

 with sulphuric acid diluted with twice its bulk of water. The 

 distilled liquid had a distinct smell of formic acid, and when 

 heated with peroxide of mercury effervescence ensued, and a 

 white micaceous deposit was formed on cooling; the salt ex- 

 amined was therefore principally formate of mercury. Had 



* See Gmelin's Handbuch, ii. 125. 3te Auf. 



