96 CANAL. 



pregnated with vegetable decompositions, it is 

 remarked, that at places of great precipitation of 

 this fluid — at great falls, which increase the rapid- 

 ity of its motion, bilious and malignant fevers are 

 more prevalent, because more miasmata are 

 brought into activity, and infused into the atmos- 

 phere, and this evil will continue until cultivation 

 prevents the supply of vegetable putrefaction. I 

 am therefore pleased at hearing that new feeders 

 have been provided. You may recollect that in 

 a former communication, 1 told you that I would 

 give you my view of the causes of the late freezing 

 and early thawing of the waters on this canal. 

 This is owing, in my opiniou, to the abundance 

 of sulphuric acid in it. It is well known that 

 water and sulphuric acid combine so intimately 

 and closely, that the compound gives out a large 

 portion caloric. Four pounds of this acid, mix- 

 ed with one pound of water, will raise the ther- 

 mometer to 300 degrees of Farenheit. There 

 are undoubtedly auxiliary, as well as counteract- 

 ing causes which act in relation to the greater 

 heat of the canals. 



The canal will however have a most beneficial 

 effect in increasing the healthiness of the country. 

 lt % will act as a great drain to carry off the ledun- 

 dant waters, and to dry up the sources of pesti 

 lence. 



