54 MASSACHUSETTS AGRICULTURE. 



various salts useful upon land, and the other, consisting of 

 vegetable or animal matter mixed with salts. The salts are 

 such as common salt, nitre, phosphate of lime, or bone ashes, 

 limestone, marl, nitrate of lime, potash, soda, &c. These, in 

 their pure state, do not afford much nutriment to plants, but 

 they act ujwn the nutriment, and prepare it for the organs of 

 the plant, by rendering it soluble and decomposing it. The 

 common manures, or a large part of them, are converted, when 

 mixed with the soil, into what is called geine, or humus. But 

 this is not in a proper state to be taken up by the roots, until 

 acted upon by other substances, when it becomes soluljle, or 

 produces carbonic acid. Common manures usually contain 

 more or loss of the salts ; but, being most of them solu))le, they 

 are carried away by rains, and hence the value of new supplies. 

 Nor does it usually require but a small quantity, as the example 

 of ashes, and gypsum, and pl:o:s])hate of lime, evinced. The 

 latter, in the state of bone dust, where the phosphate is mixed 

 with carbonate of lime and cartilage, is a manure so concen- 

 ti'ated that one ton of it is equal to foiirteen tons of farmyard 

 manure ; and almost equally concentrated is guano, and some 

 other compounds now used upon land. But I cannot go into 

 details. 



Allow me also to repeat a suggestion made in my report on 

 the Agricultural Geology of Massachusetts, respecting the use 

 of what I call muck sand, dug from a consideraljile depth in the 

 earth. It is well known to the chemist, that most of the salts, 

 so useful upon land, are dissolved b}^ rains, and carried down- 

 wards through the soil, till they meet with a water-bearing 

 stratum. There they will accumulate ; and now, let that 

 stratum — known by springs issuing from it — be dug up and 

 spread over the surface, and these salts will exert their appro- 

 priate influence u})on the crops. This very principle is the 

 chief secret of the good effects of subsoil ploughing, and I 

 doubt not but it will yet lead to valuaVdc results in the use of 

 substances drawn from a still greater depth. In some instances, 

 they certainly have produced astonishing effects. 



Though I have doubtless wearied your patience, ladies and 

 gentlemen of the society, by these details, I would gladly add 

 more. But I trust I have said enough to show how important 

 a bearing science has upon practical agriculture. The day I 



