110 BULLETIN OF THE BUSSEY INSTITUTION. 
clear filtrate from the lead sulphide no precipitate fell; hence the inference 
that the cherries contained no mannite. 
Prunes. — Bought in Boston, July 18, 1904. _Some 250 grm. of the prune 
flesh were rubbed with sand in a mortar to a friable mass. Since this mixture 
could not be percolated it was leached by treatment with many successive 
portions of hot water. Ammoniacal copper sulphate gave no precipitate on 
being added to a portion of the evaporated solution and none was obtained in 
another portion which had been treated with basic lead acetate, as above 
described. Hence the conclusion that the prunes did not contain mannite. 
Raisins. — Bought in Boston, July 21, 1904. After the removal of stems 
and seeds, the flesh of the raisins was ground up with sand in a mortar to a 
mass that was readily percolated. In the percolate, concentrated by evapora- 
tion, ammoniacal copper sulphate produced no precipitate, and none was 
obtained in another portion of the percolate which was treated with basic lead 
acetate as described above. The absence of mannite was admitted. 
Bananas.— The flesh of yellow bananas bought in Boston on July 27, 
1904, was rubbed with sand in a mortar to a thick paste, part of which was 
percolated and another part leached by way of decantation with many suc- 
cessive portions of hot water. The evaporated and filtered percolates gave no 
precipitate with ammoniacal copper sulphate and none was obtained after 
treatment with basic lead acetate. The absence of mannite was admitted. 
Apples. — No mannite was detected in Gravenstein apples bought Septem- 
ber 20, 1904. After the skins and cores of the apples had been removed, 
300 grm. of the finely chopped flesh were subjected to hot water percolation. 
The evaporated slightly acid percolate was nearly neutralized with sodium 
carbonate before adding the ammoniacal copper sulphate. The liquor was so 
dark-colored that no precipitate could be seen in it, and no precipitate was 
visible on the paper of the filter through which the liquor was passed. 
Sulphuretted hydrogen was now passed through the liquor to throw down 
the copper and, after the removal of the copper sulphide and the excess of 
sulphuretted hydrogen, basic lead acetate was added. The precipitate thus 
formed was removed by filtration and sulphuretted hydrogen was used to 
remove the excess of lead. After the removal of lead sulphide and the 
excess of sulphuretted hydrogen, ammoniacal copper sulphate was added 
and the light blue precipitate obtained was treated for mannite in the usual 
way but none was found. 
The non-appearance of any precipitate on adding ammoniacal copper sul- 
phate to the evaporated percolates from figs, prunes, raisins, bananas, and 
apples was noteworthy because precipitates had been obtained on adding 
the copper solution to the suspected solutions in all the previous experiments 
with grasses and vegetables, though in most cases, as has been shown, the 
precipitates were not due to the presence of mannite. : 
It should be added, that in several instances attempts were made to find 
mannite in grasses and clover by using basic lead acetate to remove from the 
percolates (either aqueous or alcoholic) coloring matters and other substances 
likely to cause interferences. The idea was to get rid of the excess of lead by 
means of sulphuretted hydrogen, to evaporate the filtrate from the lead sulphide ~ 
