Philos. Trans. MDCCCXVII Plate VI.p.134.

Figures de l'Examen théorique du nouveau Système de Charpente?

Ainsi le nouveau systême réunit à un très haut dégré la solidité et la durée.

Si l'on réfléchit maintenant que par les moyens dont nous avons démontré la possibilité, mathématiquement, en traitant de la stabilité, le lest se trouve rapproché du centre, ainsi qu'une partie des munitions: on verra que non seulement les vaisseaux acquièrent plus de force pour résister à l'arc, mais encore que la cause efficiente de cet arc devient moins considérable.

Les vaigres par leur direction longitudinale et leur grande longueur offrent au premier coup d'œil une idée de solidité plus grande que celles de pièces enchassées les unes dans les autres et laissant de grands triangles vides entre elles. Mais on sent bientôt le défaut d'une telle objection, lorsqu'on réfléchit que les vaigres de la cale, au lieu de résister contre des tensions n'ont à s'opposer en général qu'à des contractions; ce qui rend l'effet de leur longueur à peu près nul.

X. On a new Fulminating Platinum. By Edmund Davy, Esq. Professor of Chemistry, and Secretary to the Cork Institution. Communicated by Sir H. Davy, LL. D. F. R. S. V. P. R. I.

Read February 18, 1817.

I. Introduction.

THE metals, as is well known, closely resemble each other in their physical and chemical characters. A chain of analogies connects them together into one class, and serves to distinguish them from all other bodies with which we are acquainted. Hence, the observation of a new property, or the discovery of a new relation in any one of the metals, is a sufficient ground for extending similar enquiries to all the others. And though the same methods may not furnish equally successful results in the case of different metals, yet by varying the processes, some new truths are usually brought to light.

1

The analogies that exist between the different metals, are in some cases nearer, and in others more remote; but in all instances they are sufficiently numerous and striking to serve the ends of classification, and facilitate the progress of scientific discovery. Gold, silver, and platinum, were formerly distinguished by the epithet noble or perfect metals; this distinction, though it no longer exists, was founded on a similarity in their physical properties. Gold and silver furnish with the volatile alkali, well known fulminating

compounds. Gold and platinum appear to be more closely related to each other than they are to silver, or to any of the other metals; though separated by a number of marked distinctions, they yet possess in common, many points of resemblance. They are both soluble in the same menstrua, and can only with difficulty be made to unite with oxygene, chlorine or sulphur; and their oxides form peculiar triple compounds with acid and alkaline or earthy substances. From these analogies, and especially the last, it might be presumed that platinum, like gold, by particular treatment, was capable of furnishing a fulminating compound. Since platinum has been known to chemists, different attempts have been made to produce such a compound, but without effect. On the discovery of fulminating mercury by Mr. HOWARD, he endeavoured to communicate fulminating properties to compounds of platinum, by means of alcohol, but his trials. were unsuccessful. I have to a certain extent succeeded in this way, and my attempts have led to the observation of some new facts. I have also obtained a new compound of platinum, analogous in its properties and composition to aurum fulminans, and which, in consequence, I shall venture to designate by the term fulminating platinum. I have, indeed, already noticed a peculiar compound of platinum under this name, but the term should be restricted to the new compound, on account of its superior fulminating properties. This fulminating platinum serves to extend the existing analogies between the noble metals, and fills up a vacant space in their chemical history. In the present communication, I shall endeavour to describe this substance; but before I enter Philosophical Magazine, Vol. 40. T

MDCCCXVII.