indebted to Dr. Bowring's Parliamentary Report on the Statistics of Tuscany, and to a description of the process of manufacture in a paper by M. Payen in the Annales de Chimie et de Physique, tom. i. 3me série, p. 247. An abstract of Dr. Bowring's report appeared in the Philosophical Magazine for July 1839, and a translation of M. Payen's paper in No. 8 of the Chemical Gazette (Feb. 15th, 1843).

"As you approach the lagoons," observes Dr. Bowring, "the earth seems to pour out boiling water, as if from volcanoes of various sizes, in a variety of soil, but principally of chalk and sand. The heat in the immediate adjacency is intolerable, and you are drenched by the vapour, which impregnates the atmosphere with a strong and somewhat sulphureous smell. The whole scene is one of terrible violence and confusion-the noisy outbreak of the boiling element the rugged and agitated surface-the volumes of vapour- the impregnated atmosphere-the rush of waters—among bleak and solitary mountains.

"The ground, which burns and shakes beneath your feet, is covered with beautiful crystallizations of sulphur and other minerals. Its character beneath the surface at Monte-Cerboli is that of a black marl streaked with chalk, giving it at a short distance the appearance of variegated marble."

The place was formerly regarded by the peasants as the entrance of hell; they never passed by the spot without terror, counting their beads and praying for the protection of the Virgin. Besides the superstitious dread entertained of the lagoons, their frightful appearance and fœtid smell, arising from

VOL. II.

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the evolution of sulphuretted hydrogen gas, made them to be regarded as public nuisances, and rendered fruitless all attempts on the part of the landlords to improve the surrounding country. But since the lagoons have been turned to profitable account, a great improvement has taken place in the cultivation, and increase in the value, of the neighbouring soil. The health of the workmen, who live constantly on the spot, is in general good.

The lagoons themselves are situated on a gently sloping ground, with the manufactories at the bottom, a short distance from each other. The number of establishments is nine; of which the principal are Larderello, Monte-Cerboli, Monte-Rotundo, Sasso, Lerrazano, and Castel-Nuovo.

With some slight modifications, the routine of the operations is the same in each of the nine manufactories. A sufficiently precise idea of the process may be obtained with the assistance of the annexed engraving, which represents an imaginary section of the surface of the earth through the lagoons. This cut is an accompaniment to the paper of M. Payen before alluded to.

The lagoons consist of rude circular basins, partly excavated and partly built, situated immediately over one or more of the fissures through which the soffioni burst. They are arranged at different elevations, and connected with each other by canals to allow of the transference of the liquid from a higher to a lower lagoon. A small lake is formed in the highest of these basins by introducing the water of some adjacent mountain stream. The water is soon heated

to the boiling point, and kept in perpetual agitation by the passage of the hot vapours, which deposit most of their boracic acid in the lagoon, and afterwards rise into the air as whitish clouds. The vapours produce boracic acid only when they burst with a fierce explosion.

After having remained in the most elevated lagoon, a, for twenty-four hours, the water is allowed to descend through the canal c (by opening a plug in the canal) to the second lagoon b, where it is subjected during twenty-four hours to another impregnation. It is then passed on to the third lagoon, and so on successively, until it is arrived at the lowest

receptacle, having thus passed through from five to eight. With all these impregnations, the quantity of boracic acid in the water of the last lagoon scarcely exceeds one-half per cent. As the liquid is drawn off from one basin, it is immediately replaced by that contained in the next above.

When the solution has remained a sufficient length of time in the lowest lagoon d, it is transferred to a reservoir or cistern e, six metres (about twenty feet) square, and one metre (about three feet four inches) deep; from whence, after a few hours' rest to deposit some sedimentary matter, it is decanted either into a second reservoir f, or into the evaporating pans. ·

The arrangement for evaporating consists of two batteries, each composed of seven leaden pans, gg, 2.90 metres in breadth, and 0.35 metre in depth. The pans, which are arranged at different levels, are supported by strong wooden rafters above the masonry, so as to allow the passage of the vapour of some soffioni underneath as through a drain. The vapour enters at the bottom of the lowest pan, and passing under all the others in succession, the excess is at last given off outside the manufactory.

The first four pans of a series of seven are filled with liquid from the reservoir f, and the evaporation of the boracic solution is carried on here during twenty-four hours. The solution thus concentrated is passed on to the remaining pans by means of siphons, each pan being replenished when the liquor is withdrawn from that next above it, and the highest from the reservoir. In the last two In the last two pans the evapofar that the liquid crystallizes

ration is carried so

when transferred into vessels arranged for the pur

pose, which are wooden tubs lined with lead. The specific gravity of the crystallizing solution is from 1.072 to 1.080, at a temperature of from 173° to 176° Fahr. When the crystallization is complete, the mother-liquor is withdrawn and returned to the last two pans to be evaporated, together with another quantity of the solution; and the crystallized acid is placed in baskets to drain. It is then removed to the drying-rooms and spread on the floor in layers, which are occasionally turned. After two or three hours, or when it feels tolerably dry, the acid is packed up in casks, and sent to Leghorn for exportation.

The drying-room, represented in section at fig. 31,

is also heated by the soffioni, being constructed with a double floor for that purpose, through which the vapour is made to circulate. It is built of brick.

A battery of fourteen pans affords daily about ninety kilogrammes of saleable boracic acid. The whole product of the nine establishments varies from seven to nine thousand pounds (of twelve ounces) daily. The state of the weather has some influence on the amount of the product. In bright and clear weather, both