48 On Subdivision by Trituration and Solution. 
present they were making every exertion which the ability of the 
country and due economy would permit, to forward it to com- 
pletion. ‘lhe Committee of Congress who have the publication 
in charge, have every desire to enlarge it; but they have deeme 
it proper that the whcle work should be first completed, and then 
it could not be doubted but that the liberality of Congress would 
cause the publication to be extended, so as to place the whole 
within the means of every ee in the country. 
Prof. Agassiz here took occasion to express his opinion of 
the Expedition, and spoke of ‘ahe results in the highest terms. 
He bore testimony to the beauty as well as accuracy of the en- 
gravings, acknowledging that they were not surpassed by sed 
that had hitherto appeared in Europe. 
Arr. VIIL—On the Limit wf Subdivision by Trituration pes 
Solution, and the race te on which the hmit may be a 
nitely extended ; by B. F. Jostiy, M.D., of New Yor 
Ir any coarse and dry substance is triturated by itself it will 
continue to be permanently divided subdivided to a certain, 
but limited extent. For beyond that, ‘the blow would ‘either 
leave the parts so near each other, that they would instantly re-— 
unite by the power of the cohesive forces and again become one 
solid body, or would drive these newly separated parts against 
others or against each other, and effect their union by bringing 
them within the sphere of cohesion. 
If a flint stone were pulverized in a mortar, it would at length 
become so fine, that some of the finest of these invisible flint 
stones would, after any farther division, be soon reunited. All 
that would be necessary for their reunion and the sbinscnansinntlll 
their previous hardness, would be, to bring the parts or their mu- 
tually attractive poles, as near to each other as they had been be- 
fore their separation; for the strength of their coh 
on the degree of their proximity. ‘The approximation and amnion 
of some of these smaller than microscopic pebbles, would be pro- 
moted by the pressure of the pestle: the same blows that severed _ 
some, would unite ent so that the average size of the parts 
would remain unchange nay. 
ies, — referred to ied believing that the cohesion of all at- 
ns and of all groups sufficiently small, depends on | si and 
is allizing foree, and probably magnetism _— 
ntary form. But similar principles apply 
utic ni be ne 
