BULLETIN OF THE BUSSEY INSTITUTION. 31 
In the leached sumach, also, the proportion of potash and phosphoric 
acid was very small, as compared with the amounts that are ordinarily 
found in the leaves and twigs of plants. See the table on page 207 
of this Bulletin, Vol. I. 
Other analyses of spent woods have been published, as follows : — 
According to R. Hoffmann,* a sample of spent Brazil wood contained 
(.823% of nitrogen, and 0.4%, of ashes, which contained lime, mag- 
nesia, and traces of phosphoric and sulphuric acids, and of potash, soda, 
and oxide of iron. Stceckhardtt had previously stated, that spent 
logwood and spent Brazil wood are exceptionally rich in nitrogen, and 
had, on that account, recommended them as good materials for mak- 
ing compost; an idea which was copied by Heiden ¢ in his very 
carefully prepared treatise on manures. According to Stoeckhardt, 
the proportion of nitrogen amounted to 2.8% in logwood, and to 2.5%, 
in Brazil wood. He reports further 4 to 5% of ashes, consisting of 
lime for the most part, with small quantities of potash, and sulphuric 
and phosphoric acids. 
It will be observed that, with respect to the amount of nitrogen in 
spent dye-woods, the results of Steeckhardt and Hoffman, just cited, 
disagree totally with the results obtained in this laboratory. My 
experience is not only that the proportion of nitrogen in all the spent 
materials examined is small, but that it is particularly small in the case 
of logwood. In the face of testimony like the above, coming from 
two different chemists, I have naturally taken pains to test the ques- 
tion with special care. Each of the determinations of nitrogen, in the 
fresh and spent logwood, was repeated by a second analyst; so that 
the figures which I have given above represent results obtained by 
two separate chemists, working entirely independently of one another. 
I have been unable to detect any thing which should lead me to believe 
that the spent dyewoods can ordinarily contain much nitrogen. 
It is not at all probable, in the first place, that heart-wood, such as 
logwood is, would be specially rich in nitrogen. There is evidence, 
indeed, to be adduced hereafter (page 42), which goes to show that, on 
partially leaching various vegetable matters with water, the proportion 
of nitrogen in the leached product may sometimes be found to be 
* Tn his “ Jahresbericht iiber Agrikultur-Chemie,” 1860-61, 3. 185. 
T In his “ Chemische Ackersmann,” 1858, 4. 240. 
t “ Diingerlehre,” 1868, 2. 414. 
