BULLETIN OF THE BUSSEY INSTITUTION. 19 
and deciduous trees, etc., and with mannose prepared expressly 
for the purpose by the oxidation of mannite. They have been 
applied, moreover, not only to cases where hydrochloric acid has 
served as the hydrolyzing agent, but also to numerous instances 
where the woods have been treated with sulphuric acid of various 
degrees of concentration, and where preparations of barium and 
calcium carbonates of divers kinds have served as neutralizing 
agents, —a method, by the way, much less speedy and less con- 
venient for the purposes of this research than the use of dilute 
hydrochloric acid, as above set forth. 
» As a fairly characteristic example of the behavior of the man- 
nose-hydrazone precipitate, the following results may be cited. 
From a stock of air-dried mannose-hydrazone, prepared from 
mannite seven months previously and kept in a tightly closed 
bottle, several small parcels were taken and warmed upon a water 
bath to 85° or 90°, with smaller quantities of 4:1 alcohol than 
were needed for complete solution, and the clear solutions were 
decanted into watch-glasses. As the alcohol cooled, yellow pre- 
cipitates separated which were seen under the microscope to con- 
sist of globules, some of them joined symmetrically so as to form 
rosettes (tetrads). On filtering the alcoholic solutions, to make 
sure that every particle of the undissolved hydrazone should be 
removed, a slightly different result was obtained in that, beside 
the yeast-like globules there were now to be seen a number of 
rather poor specimens of small crystalline balls covered with 
broad, blunt spines. On trying again to change the yeast-like 
balls to proper crystals, all the above mentioned separate parcels 
of materials were put together and warmed with diluted alcohol 
(4:1) until almost the whole of the hydrazone had dissolved. 
The decanted liquor was then allowed to evaporate very slowly. 
The yellow sediment showed under the microscope many smooth 
globules and some with broad spines. On repeating the trial and 
allowing the alcoholic solution to evaporate still more slowly ina 
cold room, a similar result was obtained. But on starting anew 
with some of the same, original, air-dried, finely powered hydra- 
zone and heating it to 80° or 85°, with a mixture of three parts of 
aleohol of 95 per cent. and one part water, the decanted liquor 
deposited on cooling an abundance of true crystals, many of 
which were separate, individual, transparent, rhomboidal plates, 
