2S6 Jcid Liquid Jrom Potash and Alcohol. 



small quantity of cold water, for the purpose of taking up the 

 more soluble acetate of lead : and the solution decanted. A 

 quantity of fine spicular crystals remained undissolved. These 

 were found to be of very sparing solubility in cold water ; but 

 their solution was effected by heat. The oxide of lead was then 

 very carefully precipitated by sulphuric acid ; and the sulphate 

 of lead allowed to subside. The decanted liquid was then satu- 

 rated with magnesia, filtered, concentrated, and set aside. In 

 four or five days it was almost entirely transformed into well 

 characterised crystals of formate of magnesia ; the peculiar some- 

 what circular and tubular form of which is extremely well cal- 

 culated to enable a person accustomed to observe them, as crys- 

 tallized on the small scale, to determine the existence of formic 

 acid. The appearance of these crystals, together with the spar- 

 ingly soluble salt of lead, thus left no doubt as to the presence 

 of this acid in the liquid under examination. 



The existence of acetic acid in the same fluid was best ascer- 

 tained by its action on peroxide of mercury. If peroxide of 

 mercury be boiled in pure acetic acid, it is dissolved, and a so- 

 lution of peracetate of mercury obtained. If it be treated in 

 the same way with formic acid, it is reduced, metallic mercury 

 being precipitated with effervescence. If instead of either 

 acid in a state of purity, a mixture of the two acids be boiled 

 with the red oxide, the formic acid not being in excess, then this 

 latter acid exercivSes its reducing action on the oxide, with effer- 

 vescence ; but before the reduction is complete, the acetic acid 

 arrests the metal in the state of protoxide, and a precipitation of 

 protoacetate of mercury ensues on the cooling of the liquid. 

 This is the action which I have constantly obtained on treating 

 peroxide of mercury with a mixture of acetic and formic acids, 

 the latter not being in excess ; and it is precisely this action 

 which I have observed on treating that oxide with the acid li- 

 quid in question. For this purpose, however, it is necessary to 

 concentrate it as much as possible, by saturating it with an al- 

 cali, and redistilling it with sulphuric acid ; and if the concen- 

 tration has not been carried far enough, the experiment will not 

 succeed. 



These results leave, I conceive, no doubt that the acid liquid 

 obtained in the manner I have described, consists of a mixture 

 of acetic and formic acids. I have also examined the salts it 



