238 Nature of the Lampic Acid. 



containing sulphuric ether, was placed at the bottom of a 

 large cup. A piece of spongy platinum, of the size of a large 

 pea, was then ignited, and suspended by a fine platinum-wire 

 in a large glass funnel, which was inverted in the cup, so as 

 to bring the spongy platinum a little way above the surface 

 of the ether. An alembic head was then suspended a short dis- 

 tance above the upper part of the funnel. The spongy plati- 

 num, and the whole length of the platinum-wire, continued to 

 glow as long as any ether remained, and a copious production 

 of pungent acid vapours took place, a great part of which were 

 condensed within the funnel, and fell back into the cup ; and a 

 part of those which escaped from the funnel were condensed in 

 the alembic head. By placing one or two shps of glass below 

 the under edge of the funnel, the free access of air was allowed 

 to the inside. By a series of operations of this kind, any quan- 

 tity of lampic acid which may be required is obtained in no very 

 long time. 



The acid thus prepared possessed the usual reducing proper- 

 ties of the lampic acid. Heated with protonitrate of mercury, 

 there was effervescence and precipitation of metallic mercury. 

 Heated with peroxide of mercury, there was effervescence, and, 

 on cooling, a very copious deposit of protoacetate of mercury. 



The latter of these experiments demonstrates the presence of 

 acetic acid in the lampic acid. To ascertain whether it contained 

 formic acid, I had recourse, as before, to the salts of magnesia 

 and lead. Portions of the acid were saturated with magnesia, 

 filtered, concentrated, and set aside. When the acid employed 

 was that portion which had been collected in the alembic head, 

 the formation of crystals of formate of magnesia could be more 

 readily observed than when it had been collected in the cup, the 

 former portion probably containing a larger proportion of for- 

 mic acid, perhaps from that acid being more volatile than the 

 acetic. When the acid from the alembic head was employed, 

 I could generally observe, in the course of five or six days, with 

 the lens, an incipient formation of minute crystals, which slowly 

 increased in size and number ; and in some instances, in the 

 course of a week or two, the formation of crystals was sufficiently 

 obvious, although in others it was less distinct. Where the acid 

 collected in the cup was employed, the result was always much 



