508 Transactions of the American Institute. 



ney, with the request that he make a comparative analysis of them 

 and report upon their mechanical and chemical character. As a pro- 

 per introduction to the question in hand, I call for the report of our 

 chemist. 



Mr. Jas. A. Whitney. — Mr. Chairman : With reference to the 

 samples of subsoil from the " Mapes farm " and from Salem county 

 N. J., submitted some time since for analysis, the writer regrets that 

 the imperative pressure of other engagements temporarily interrupted 

 the investigations at an early stage. He is, however, able to lay 

 before the club the results of the tests as far as made. Both of the 

 samples were very dry when taken in hand. That from the Mapes 

 farm was so hard and compact as to require considerable effort in 

 pulverizing it in a mortar and possessed a brick-red color, due, as was 

 shown by testing with the ferro-cyanide of potassium, to the pres- 

 ence of peroxyd of iron. The tenacious character of this subsoil 

 indicates that in its natural condition it must present a strong barrier, 

 not only in the downward passage of plant-roots, but also to the 

 drainage of water from the surface soil, and the alternating influences 

 of frost and warmth. More than this, the decay of any organic 

 matter that may exist in the subsoil out of the reach of air, would 

 abstract oxygen from the peroxyd, and thus convert it into a pro- 

 toxyd of iron, a mineral very injurious to all vegetable growth. 

 Subjected to the usual tests this subsoil gave of organic matter,' 

 51-lOOOtli, or a little more than five per cent. The soluble portion 

 included in this amounted to only 6-100 of one per cent. The 

 proportion of mineral matter soluble in water was 35-100, or slightly 

 more than one-tliird of one per cent. The sample of Salem county 

 subsoil consisted of yellowish, friable earth, easily crushed to powder 

 between the fingers, and showing in its structure a far greater pro- 

 portion of silica than the other. It contained 3 65-100, or upward 

 of three and one-half per cent of organic matter, and of this three- 

 tenths of one per cent were soluble in water. Of soluble mineral 

 matter it had one and one-fourth per cent. The sample from the 

 Mapes farm was taken from a field that for years had been subjected 

 to the deep tillage for which that farm has become celebrated, and the 

 extent to which plants are encouraged by this system to send their 

 roots deep into the ground for nutriment is shown by the large 

 amount, about five per cent, of organic matter or humus indicated by the 

 analysis. This is evident if we consider alone the mechanical structure 

 of the subsoil, hard, compact and tenacious, and presenting in its 



