206 BULLETIN OF THE BUSSEY INSTITUTION. 
the leached ashes of commerce, charged with more than a third their 
weight of moisture, no more than 14% of phosphoric acid can be 
allowed on the average, as appears from Johnson’s figures on page 203. 
The following table, to which frequent allusion has been made in 
the preceding pages, has been compiled from the published statements 
of various chemists who have analyzed the ashes of woody plants. As 
has been already indicated most of the estimations of potash and phos- 
phoric acid were made in ashes that had been prepared expressly for 
analysis. A more complete table than the one here given could un- 
doubtedly be constructed, at the cost of considerable time and trouble. 
It is believed, however, that this one will be sufficient to give a just 
idea of what has been done hitherto by chemists in this department of 
ash analysis, and to illustrate the allusions to such work that have 
been made in the text.* , 
The column relating to “salts soluble in water, or crude potashes,” 
has been given partly for the sake of future reference, and partly be- 
cause the figures contained in it, may, in the lack of more precise indi- - 
cations, serve to indicate approximately the amount of real potash that 
the sample in question contained. or in case the matter reported as 
“salts soluble in water, or crude potashes,” were all carbonate of potash, 
as by far the larger part of it actually is in most instances, the amount 
of real potash could at once be calculated, since in every 100 parts of 
carbonate of potash there are 68 parts of real potash. A rough ap- 
proximation to the amount of potash in any sample of ashes may there- 
fore be had by taking 58, or 7 of the figures given in the column 
relating to salts soluble in water. 
ply the weight of the soluble matters that are removed by water, so that the 
proportion of phosphoric acid in the dry leached product may be very nearly 
the same as it was in the fresh ash. 
* It will be noticed that the figures in the table all refer to quantities of wood 
and of ashes that have been weighed, not’ measured. But since both wood 
and ashes are commonly bought and sold by measure in this country, it may be 
well to remark that a bushel of household ashes is said to weigh about 48 
pounds on the average. With regard to the weight of different kinds of woods, 
itappears from the experiments of Bull (“ Transactions of the American Philoso- 
phical Society,” Philadelphia, 1880, 3. 60), that there are about 1800 Ibs. of dry 
wood in a cord of white pine, 1900 lbs. in a cord of pitch pine, about 3300 Ibs. in 
a cord of the ordinary oaks, 3800 lbs. in a cord of white oak, and as much as 
4500 lbs. in a cord of shell-bark hickory. Not to repeat Bull’s copious table, it 
may be said in general terms, that he usually found about 2500 or 8000 Ibs. of 
dry wood to the cord. 
