Physics and Chemistry. 308 
finite ane acting upon a body of finite magnitude which is free 
may be zero. 
(4. “The proper work of force is to generate or destroy mo- 
mentum ;* and the work done by the force in a given time will 
= poy measured by the momentum created or destroyed in 
that 
The measure thus proposed, in fact, differs from the pe 
measure epiainietl by Professor Maxwell less than might at firs 
sight be supposed ; for when T is very small, (1) beco mes 
work = F's = Mv.V,. 
Thus, while I nae that the work done in a short interval of 
time ‘under the above circumstances is pase on measured by the 
momentum generated during the time, accordin ae be views 
upon the subject which are generally reeniad: it is measured by 
the Be pat bal ne momentum generated and "the initial velocit 
reasonableness of which, I Bd a it wi 
blis 
| % Rift 
ae ees ore in Storia eg: cig ue nel R. Tetitate indumtisle 
: Ey eaonale di Terni. Prato, Tipografia Giachetti, Figlio e C. 
9, pp. 456, Svo. ae this cas Signor Bellucci, who is now 
Prof | in the University of Perugia, gives a very interesting 
and valuable résumé of the researches upon the subject of ozone, 
: ears. 
tions of the eee investigators, the sources bag carefully in- 
dicated by foot- The discussion is divided into five parts, a 
Summary of which will give an idea of the scope and general 
character of the w 
a first traces tie progress of discovery i” Me ozone from the 
time of Van Marum, who in 1788 observe e peculiar odor 
communicated to oxygen by the passage of the electrical dis- 
* No doubt f ly, of causing a body to de- 
orce has another effect—that, rap re ke two effects, vit the 
ut an indefinitely 
direct ac 
of the third order of small quantiti 
es at most. : : 
"san this it follows that the work done by the force F acting during the 
a body which is free to move will be measured by FT. 
