Econojnical Geology of Massachusetts. 371 



They show us the amount of nutriment in the soils of Massachusetts ; also how 

 much of it is in a fit state to be absorbed by plants, and how much, of it will need 

 further preparation. As this is probably the first attempt that has been made to ob^ 

 tain the amount of geine in any considerable number of soils, we cannot compare 

 the results with those obtained in other places. They will be convenient, however, 

 for comparison with future analyses; and we learn from them, that geine, in both 

 its forms, abounds in the soils of the state, and that it most abounds where most 

 attention has been paid to cultivation. It ought to be recollected, that I took care 

 not to select the richest or the poorest portions of our soils ; so that the geine in 

 this table is probably about the average quantity. It is hardly probable that the 

 number of specimens analysed from the difierent varieties of our soils is sufficiently 

 large to enable us to form a very decided opinion as to their comparative fertility, 

 especially when we recollect how much more thorough is the cultivation in some 

 parts of the state than in others. It may be well, however, to state the average 

 quantity of geine in the different geological varieties of our soils, which is as 

 follows : 



Soluble Geine. Insoluble Geine, 



g.l5 

 5.22 



- - - 2.14 

 4.00 

 4.53 

 4,04 



- - 4.60 

 4.60 

 3.40 



- - 3.87 



- - - 4.50 

 4.10 

 6.10 



One fact observable in the above results may throw doubts over the fundamen- 

 tal principles that have been advanced respecting geine ; viz. that it constitutes the 

 food of plants, and that they cannot flourish without it. It appears that our best 

 alluvial soils contain less geine, in both its forms, than any other variety, except 

 those very sandy ones that are not noticed in the above results, because their num^ 

 ber is so small. Ought we hence to infer that alluvium is a poor soil? I appre- 

 hend that we can infer nothing from this fact against alluvial soils, except that they 

 are sooner exhausted than others, without constant supplies of geine. For if a soil 

 contain enough of this substance abundantly to supply a crop that is growing upon 

 it, that crop may be large although there is not enough geine to produce another. 

 Now analysis shows that our alluvial soils contain enough of geine for any one 

 crop : and I apprehend that their chief excellence consists in being of such a de- 

 gree of fineness that they allow air, moisture, and lime, rapidly to convert vegeta- 

 ble matter into soluble geine, and yield it up readily to the roots of plants : but I 

 presume that without fresh supplies of manure, they would not continue to pro- 

 duce as long as most of the other soils in the state. A considerable part of our al- 

 luvia are yearly recruited by a fresh deposite of mud, which almost always con- 

 tains a quantity of geine and of the salts of lime, in a fine condition for being ab-- 

 sorbed by the rootlets of plants. And on other parts of alluvial tracts, our farmers, 

 I believe, are in the habit of expecting but a poor crop unless they manure it yearly. 

 Yet so finely constituted are these soils, that even if exhausted, they are more easily 

 restored than most others ; so that taking qll things into the account, they fire 



