EVOLUTION OP SULPHURETTED HYDROGEN. 
257 
" The observation of Signor Giorgini has been drawn to 
the state of tbe atmosphere in the neighborhood of certain 
marshes on the borders of the Mediterranean; and by reference 
to historical data, and various documents, he has proved the 
great importance which attaches to the circumstance of their 
being at times in communication with the sea, so as to have a 
mixture formed between their waters and that of the sea. 
Both ancient and modern authors have announced the fatal 
effects produced in the neighborhood of marshes by such mix- 
ture, and a local belief of the same is very common and 
strong. 
" On the south of the Ligurian Apennines, is a marshy 
shore, bounded on the west for twelve miles by the Mediter- 
ranean, on the south by the river Serchio, and on the north 
by the rivei Frigido, a torrent commencing at the foot of 
the Apennines in the state of Massa di Carrara, running three 
or four miles over the land, and then falling into the sea. The 
plain is from two to four miles wide, and is traversed by a 
few short torrents or streams ; among these are the rivers 
Camajore and Pietra Santa, which divide the plain into three 
separate basins. The rain and spring waters which flow into 
the three basins mentioned, are slowly discharged into the 
sea by natural or artificial canals, penetrating the sand-bank, 
which exist on the sea side. 
" The level of these stagnant waters is between that of high 
and low water in the neighboring sea, there being but little 
difference between these two points in this part of the Medi- 
terranean, In this state of things, formerly, when the waters 
of the sea arose from any circumstance (unless the waters of 
the marshes were very high,) 'they used to return up the 
ditches, fill the basins, and inundate the country to the foot of 
the mountains ; and with a north west wind the waves used 
to penetrate with force to the interior. The mixture of fresh 
and salt water thus formed, and which in summer was rarely 
changed, became corrupt, and spread infection over the neigh- 
borhood of the most destructive kind. 
" In this way the effects of the malaria were reproduced 
Vol. vii.— No. nr. 33 
