disposition of the areas of fusion, Tresca feels justified in concluding
that the development of heat depends upon the form of the faces and the
intensity of the shock; that the points of greatest heat correspond to
the points of greatest flow of the metal, and that this flow is really
the mechanical phenomenon which gives rise to the calorific phenomenon;
that for action sufficiently energetic and for bars of sufficient
dimensions, about 0.8 of the labor expended on the blow may be found
again in the heat; that the figures formed in the melted wax for shocks
of less intensity furnish a kind of diagram of the distribution of the
heat and of the deformation in the interior of the bar, but that the
calculation of the coefficient of efficiency does not yield satisfactory
results in the case of moderate blows.--_Comptes Rendus_.

* * * * *




TIN IN CANNED FOODS.

[Footnote: Read at an evening meeting of the Pharmaceutical Society,
March 5, 1884.]

By PROFESSOR ATTFIELD, F.R.S., ETC.


From time to time, during the past twelve years, paragraphs have
appeared in newspapers and other periodicals tending in effect to warn
the public at least against the indiscriminate use of canned foods. And
whenever there has been any foundation in fact for such cautions, it has