22 Dr. Bowring on the Boracic Acid Lagoons of Tuscany. 



formed by the introduction of the mountain streams. The 

 hot vapour keeps the water perpetually in boiling ebullition; 

 and after it has received its impregnation during twenty- four 

 hours at the most elevated lagoon, the contents are allowed 

 to descend to the second lagoon, where a second impregnation 

 takes place, and then to the third, and so forth, till it reaches 

 the lowest receptacle ; and having thus passed through from 

 six to eight lagoons, it has gathered one half per cent, of the 

 boracic acid. It is then transferred to the reservoirs, from 

 whence, after a few hours rest, it is conveyed to the evapora- 

 ting pans, where the hot vapour concentrates the strength of 

 the acid by passing under shallow leaden vessels from the 

 boiling fountains above, which is quite at a heat of 80° of 

 Reaumur*, and is discharged at a heat of 60°t' There are 

 from ten to twenty pans, in each of which the concentration 

 becomes greater at every descent till it passes to the crystal- 

 lizing vessels, from whence it is carried to the drying rooms, 

 where, after two or three hours, it becomes ready to be packed 

 for exportation. 



The number of establishments is nine J. The whole amount 

 produced varies from 7000 to 8000 pounds (of 12 ounces) 

 per day. The produce does not appear susceptible of much 

 extension, as the whole of the water is turned to account ; the 

 atmosphere has, however, some influence on the result. In 

 bright and clear weather, whether in winter or summer, the 

 vapours are less dense, but the depositions of boracic acid 

 in the lagoons are greater. Increased vapours indicate un- 

 favourable change of weather, and the lagoons are infallible 

 barometers to the neighbourhood, even at a great distance, 

 serving to regulate the proceedings of the peasantry in their 

 agricultural pursuits. 



It had been long supposed that the boracic acid was not to 

 be found in the vapours of the lagoons ; and when it is seen 

 how small the proportion of acid must originally be, it will 

 not be wondered at that its presence should have escaped 

 attention. In the lowest of the lagoons, after five, six, and 

 in some cases a greater number of impregnations, the quantity 

 of boracic acid given out does not exceed one half per cent.: 

 thus if the produce be estimated at 7500 pounds per day, the 

 quantity of saturated water daily discharged is a million and a 

 half of Tuscan pounds, or five hundred tons English. 



The lagoons are ordinarily excavated by the mountaineers 

 of Lombardy, who emigrate into Tuscany during the winter 



• The boiling point. f 167° of Fahrenheit. 



X The principal are Monte Cerboii, Monte Rotondo, Siisso, Serazzano, 

 and Castehmovo. 



