210 



Organic acids and moisture . . . 14.46 



Carbonate of lime ..... 72.82 



Magnesia as a base ..... 7.32 



Biphosphate of magnesia .... 2.20 



96.80 



A little silica, and a mere trace of carbonate of iron, were de- 

 tected. The brown color of the surface is produced by humus ; 

 and associated with the humic acid and the biphosphate of mag- 

 nesia is some ammonia, forming a humate of ammonia in the 

 organic part, and double phosphate of ammonia and magnesia in 

 the mineral part. 



The carbonic acid is insufficient in quantity to engage both the 

 magnesia and lime, I have therefore regarded the condition of the 

 lime as a carbonate, and the magnesia as in union with crenic and 

 humic acids. 



The composition of this substance indicates that crenates of 

 lime and magnesia, and some ammonia phosphate of magnesia, 

 were absorbed from the soil ; and in the subsequent decomposition 

 the carbonate of lime formed was rendered more compact and 

 hard by the portion of crenate, which is undecomposed, acting as 

 a cement. The humus and humic acids are the usual attendants 

 of this decomposition. 



Although stony matter occurring in trees has been frequently 

 mentioned, the information possessed on the subject had led me 

 to suppose that the mineral part occupied the space near the con- 

 centric rings which the section of a tree presents, and not the 

 medullary canal, as in this instance. 



Mr. Dillaway, the Librarian, announced the reception 

 of the scientific portion of the library of the late Dr. T. 

 W. Harris, consisting of about 250 volumes, especially 

 rich in the department of Entomology. This valuable 

 donation is due to the liberality of John P. Gushing, 

 Esq., of Watertown, who was also the largest contrib- 

 utor for the purchase of the Harris Cabinet of Insects 

 and Manuscripts, also the property of the Society. The 

 thanks of the Society were voted to Mr. Gushing for this 



