74 Intelligence and Miscellaneous Articles, 



at their origin and carried across by lead pipes or by subterranean 

 conduits below the boilers. Thus the fabrication is extremely simple, 

 the locality itself furnishing the means of carrying it on. A single 

 discharge of the vapours is sufficient to throw into ebullition, almost 

 immediately, 20 or 30 caldrons of a capacity of 20 barrels, which 

 may be estimated at 84,000 pounds of liquid impregnated with bo- 

 racic acid. Before allowing the vapours to escape, they direct them 

 under the ovens in order to free the acid from its hygrometric moist- 

 ure. Of late the somewhat complex system of boilers and coolers 

 has been simplified by substituting rectangular tables of lead of 20 

 or 30 metres, divided at small intervals by transverse parallel divi- 

 sions, but whose height is never raised above that of the edges. These 

 tables have an inclination of two to three degrees. The water of the 

 last lagoon is introduced upon the upper side, in small quantities. 

 The hot vapours for evaporating are conducted in such a manner that 

 they act upon the lower surface. The liquid after having filled the 

 first compartment is diffused very gradually into the second, then 

 into the third, and so successively to the last, where it reaches such 

 a state of concentration that it deposits the crystallized acid ; the 

 workmen remove it immediately by means of wooden scrapers. This 

 mode of gradual concentration is very ingenious, and requires so few 

 hands that it may almost be said that the acid is obtained without 

 expense. From 1818 to 1845 the quantity of acid manufactured was 

 33,349,097 Tuscan pounds. From 1839 to 1845 the mean quantity 

 has been two millions and a half of pounds. 



Thus in estimating the product at 7500 pounds per day, the 

 quantity of saturated water upon which they operate daily is 

 1,500,000 lbs. daily, and annually 547,500,000 lbs. 



This labour brings to Tuscany 12 millions of pounds (10 millions 

 of francs), and it is surprising that it should have remained unpro- 

 ductive during so many ages, and that it should have been reserved 

 for the skill of M. Larderel, now Count of Monte Cerboli, and before 

 1818a simple wandering merchant, entirely unacquainted with scien- 

 tific researches, to discover the fugitive vapours and render them a 

 source of inexhaustible wealth. 



The violence with which the burning vapours escape gives rise to 

 muddy explosions, when a lake has been drained by turning its 

 waters into another lake. The mud is then thrown out, as solid 

 matters are ejected from volcanos, and there forms in the bottom of 

 the lake a crowd of those little cones of eruption whose activity and 

 play recall exactly under another form the horniios of Malpays. 

 Their temperature varies from 120° to 145° centigrade, and the 

 clouds which they form above the lagoons constitute true natural 

 barometers, whose greater or less density rarely disappoints the pre- 

 dictions that they announce. 



While in an industrial point of view, the lagoons occupy the first 

 rank among the natural products of Tuscany, they place new re- 

 sources at the disposition of science, permitting the investigation of 

 various geological phenomena, even under the direction of the will 

 of the experimenter. The metamorphic gypsum which we have seen 

 produced at Pereta under the influence of sulphuretted hydrogen 

 vapours, is formed at the lagoons, which, like those of Monte Cerboli 



