IRRiaATION. 233 



by irrigation, is found in the impurity of water ; the salts 

 and suspended matter, the slime and genial mud of freshets. 

 Perhaps the effect due to this cause, cannot be better illus- 

 trated, than by a statement of those substances, and their 

 amount, which fill the waters of the Merrimack ; a flood of 

 blessings ! which rolls by those engaged in the din and hot 

 Iiaste of manufiictures, as unheeded as was the earthquake 

 which thundered and trembled, and rolled away under the 

 feet of the fierce soldiery in an ancient battle. In the year 

 1838, during twenty-three days of freshets, from May till 

 November, no less than 71874063 lbs. of geine and salts 

 rolled by the city of Lowell, borne seaward. During the 

 five days of the great freshet, from January 28th, to Febru- 

 ary 1st, 1839, no less than 35970897 lbs. of the same matter 

 rolled by at the rate of from 112128 lbs. to 20405397 lbs. 

 per day ; each cubic foot of water bearing onwards, from 1^ 

 to 30^ grains. This is only the suspended matter. That 

 which is chemically dissolved by the waters, the fine filmy 

 deposit, which occurs in a few days after the coarser and 

 grosser matters subside, and the matter ordinarily suspended 

 in the water of the river added to the above for the year 

 1838, give a grand total of 839181 tons of salts and geine, 

 which were rolled down in the water of the Merrimack 

 river. 



284. What is tKis matter "? Is it of any agricultural 

 value ? The answer to the first question will answer both. 

 The dissolved salts are sulphate and geate of lime, and the 

 fine deposit occurring after the water has settled, is composed 

 of one-half geine, and the remainder of salts of lime and 

 silicates. The great agricultural value is found in the clayey 

 deposit, which occurs in the first few days. The coarser 

 part, that which collects about the foot of rocks, and falls, 

 and eddies, is composed as follows : 



