Nature of the Lampic Acid. 2^ 



slower and less manifest, but still the formation could be obser- 

 ved, after some weeks, with the lens. By far the readiest and 

 most satisfactory result, however, was obtained by the method 

 formerly described, founded on the different solubility of the 

 salts of lead. A quantity of lampic acid, collected in the cup, 

 was saturated with carbonate of lead, filtered, concentrated, and 

 crystallized spontaneously. The crystals were treated with a 

 small quantity of cold water, to take up the acetate of lead. 

 Undissolved spicular crystals were separated, and found to be 

 of sparing solubility in cold water ; but were dissolved by the 

 aid of heat. The oxide of lead was then carefully separated, 

 as before, by means of sulphuric acid, and the clear liquid satu- 

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

 four or five days, the formation of crystals was observed to be 

 commencing, and in three or four more, nearly the whole was 

 transformed into distinct crystals of formate of magnesia. Well 

 characterised formic salts of lead and magnesia had thus been 

 obtained, leaving, as I conceive, no doubt of the existence of 

 formic acid in the lampic acid. 



The synthetic proof of the nature of this acid was equally sa- 

 tisfactory. I made mixtures of acetic and formic acids ; and 

 found, so far as my examination reached, that all the leading 

 curious effects on metallic solutions and oxides, which were ob- 

 served by Mr Daniell to be produced by the lampic acid, might 

 be imitated with the mixed acids. Thus, when a solution of 

 chloride of gold was heated with a mixture of acetic aud formic 

 acids, the liquid became muddy, and green by transmitted light, 

 and the tube was coated with metallic gold. The colour of 

 chloride of platinum was deepened by similar treatment. From 

 a concentrated solution of nitrate of silver, the silver was thrown 

 down as a brown powder. When a solution of peroxide of 

 mercury, in acetic acid, was treated with a mixture of the two 

 acids, and then allowed to cool, a copious precipitation of proto- 

 acetate of mercury ensued ; and, as formerly stated, the same 

 result followed when the peroxide was directly heated with the 

 mixed acids. 



I trust, therefore, that I shall be considered as warranted in 

 concluding, that the lampic acid, from sulphuric ether, consists 

 of a mixture of acetic and formic acids ; and that it is the last 



