hisaluhrity of the Air of the Maremma. 237 



these soils in consequence of their peculiar nature and the ab- 

 sence of vegetation, and being thereby furrowed and ravined 

 in all directions, fresh surfaces are continually exposed to the 

 action of the atmosphere. 



Nor can it be questioned that this soil exhales gases which 

 are unfit for respiration. The ventilation of wells and adits 

 opened in mattajoiie is very difficult of execution, and fre- 

 quently requires the use of furnaces to support respiration and 

 combustion. Does this circumstance produce, or not, any 

 noxious effect? This question is put, but not answered by 

 the author. 



Insalubrity produced by Mineral Waters. 



It has been long known, and philosophers have testified 

 the fact, that salt water, when mixed with marshy waters, 

 occasions insalubrity : pestilential marshes have been ren- 

 dered almost completely healthy when the access of salt 

 water has been prevented. The most striking example of this 

 fact occurs in the memoir of M. Giorgini, ' On the Marshes 

 of Pietrasantino and Montignosino' {Ann. de Chim. xxix.). 

 M. Savi has discovered examples of similar effects in the in- 

 fluence of mineral waters. Such was the lake of Rimigliano, 

 situated between Torre San-Vincenzo and the promontory of 

 Populonia. This marsh ceased to exist in 1832. Before 

 this period it received, by the fossa calda, the mineral and 

 thermal waters of the source of the Caldana, near Campiglia. 

 These waters contain bicarbonate of lime and magnesia, chlo- 

 rides of calcium and magnesium, sulphates of soda, lime and 

 magnesia. The waters of the ocean had no access to this 

 lake. 



The bottom of the lake, lying on a black stratum of marine 

 origin, was formed of a yellowish white substance; it was of a 

 pasty, and sometimes of a gelatinous consistence, and filled 

 with fragments of the stalks of the Chara hispida (the only 

 plant vegetating in this marsh), in a state of decomposition. 

 When this slime was stirred, it emitted an intolerable smell : 

 this, after analysis, was attributed by the author to sulphu- 

 retted hydrogen, and to a peculiar organic substance [jmte- 

 rine); the solid portion of the deposit was a mixture of organic 

 matter, carbonate and sulphate of lime, &c. The mineral 

 waters conveyed by the J'ussa calda being diverted by another 

 channel, and the lake running into the sea, the bottom of the 

 marsh was soon covered with flourishing vegetation. Were 

 the malignant emanations of lake Rimigliano derived from 

 different causes from those which exist in common submarine 

 marshes? It will be observed that this locality exhibits two 



