8. It is supposed by some philosophers that _light is subject to the same laws of attraction that govern all other material substances_--and that _it is imbibed and forms a constituent part of certain bodies_. This has been inferred from the phenomena of the _Bolognian stone_, and what are generally called the _solar phosphori_. The Bolognian stone was first discovered about the year 1680, by Leascariolo, a shoe-maker of Bologna. Having collected together some stones of a shining appearance at the bottom of Monte Paterno, and being in quest of some alchemical secret, he put them into a crucible to calcine them--that is, to reduce them to the state of cinders. Having taken them out of the crucible, and exposed them to the light of the sun, he afterwards happened to carry them into a dark place, when to his surprise, he observed that they possessed a self-illuminating power, and continued to emit faint rays of light for some hours afterwards. In consequence of this discovery, the Bolognian spar came into considerable demand among natural philosophers and the curious in general; and the best way of preparing it seems to have been hit upon by the family of Zagoni, who supplied all Europe with Bolognian phosphorus, till the discovery of more powerful phosphoric substances put an end to their monopoly.--In the year 1677, Baldwin, a native of Misnia, observed that chalk dissolved in aqua-fortis exactly resembled the Bolognian stone in its property of imbibing light, and emitting it after it was brought into the dark ; and hence it has obtained the name of Baldwin’s phosphorus.