}50 CALCAREOUS MANURES-PRACTICE. 



" It even seems that calcareous countries are unhealthy only when they 

 are interspersed Ijy marshes, or when some causes, foreign to the soil and 

 climate, determine tlie unhealthiness, as in countries on the borders of the 

 sea, where the flowing of the tide and the mincrjing of salt and fresh wa- 

 ters infect the air, by the deleterious emanations of their combination. 

 This cause of unhealthiness is regarded as a certain fact ; for salubrity is 

 generally seen to appear whenever this mixture of waters is prevented. 



" In the valleys of rivers bordered by calcareous mountains, which enclose 

 unhealthy countries in their interior, insalubrity commences there only as 

 the calcareous soil, which is attached to the mountain, gives place to sili- 

 cious soil. In the same plain, and far from a mountain, salubrity is seen to 

 diminish in the same proportion that the calcareous soil of the surface does; 

 and the communes of Bresse, which have an abundance of mai'ly or calca- 

 reous soils, are much more remarkable for their salubrity than those on 

 the white lands (terrain blanc*.) "While the ponds of Dombe, which are 

 on the silicious soil, appear to be one of the greatest causes of unhealthi- 

 ness, those of Bresse, which are on calcareous lands, do not show such 

 effects in the country where they are found ; so, likewise, the ponds of the 

 country situated between the Veyle and the Reyssouze, to the north-west 

 of Bourg, which are generally on calcareous soil, do not appear to injure 

 the healthiness of the country in any manner. 



" For the support of this system, we will also cite the ponds of Berri on 

 calcareous soil, whose emanations have nothing unhealthy ; the laying dry 

 of the ponds of Parra^ay, in the canton of Lignieres, ha^ added nothing to 

 the healthiness of a calcareous country naturally healthy. And in the same 

 canton, the pond of Villiers, which is said to be seven leagues in circu-m- 

 ference, does not cause diseases on its borders. Besides, during the month 

 of August, the water of the ponds on calcareous soil does not become 

 blackish, as often happens in silicious ponds. The water would then be 

 made wholesome by the calcareous principle, in the same way as their 

 emanations. 



" In fine, Dombe and Sologne, and a number of other countries are un- 

 healthy, and subject to intermittent fevers, without being marshy ; but therr 

 soil is likewise silicious, and the land moist. Puisaye, and a part of Bresse, 

 in similar land, which contain little or no calcareous soil, have also many 

 autumnal fevers." — (^Translation from ' Essai sxir la Marne.') 



CHAPTER XVI. 



DIRECTION.^ rOR THE MECHANrcAL OPERATIONS OF APPLYING MARL AS MANURE. 



The great deposite of fossil shells, which custom has miscalled marl, is 

 in many places exposed to view in most of the lands that border on our 

 tide-waters, and on many of their small tributary streams. Formerly, it 

 was supposed to be limited to such situations ; but since its value as a ma- 

 nure has caused it to be more noticed and sought after, marl has been 

 found in many other places. It is often discovered by the digging of wells, 

 but lying so deep that its value must be more highly estimated than at 



* The reader of M. Puvis' essays on lime and marl, which were inserted in vol. iii., 

 may remember that this provincial term and others (plateaux argillo-silicieux, &.c.) were 

 there used to designate a peculiar kind of soil, destitute of calcareous matter, stiff, in- 

 tractable and poor— and which seems precisely of the character of the poor ridge lands 

 of lower Virginia, to which calcareous manures are so peculiarly adapted. — Translator. 



