4-3 



employed, were now injected into the circulation of a dog. He in- 

 stantly lost all power of motion ; the breathing became slow, the 

 pulse hardly to be felt. In ten minutes it was 84 ; in twenty minutes 

 at 60 ; in an hour at 115, with the respiration so quick as scarcely 

 to be counted. In two hours the pulse was 150, and very weak. In 

 the mean tune the animal was purged ; and he vomited, first a bilious 

 fluid, and then bloody mucus ; and after lingering in an extremely 

 languid state five hours, expired. 



On dissection, the internal coat of the stomach and intestines were 

 found inflamed in a greater or lesser degree universally. 



The facts here adduced, says the author, go as far as it is possible 

 to prove that the action of Colchicum autumnale on the different parts 

 of the body is through the medium of the circulation, and not hi con- 

 sequence of its immediate effects on the stomach. 



On the Cutting Diamond. By William Hyde Wollaston, M .D. Sec.R.S. 

 Read May 2, 1816. [Phil. Trans. 1816, p. 265.] 



The author, having never met with any satisfactory explanation 

 of the property which the diamond possesses of cutting glass, has 

 endeavoured, by experiment, to determine the conditions necessary 

 for this effect, and the mode in which it is produced. The diamonds 

 chosen for this purpose are naturally crystallized, with curved sur- 

 faces, so that the edges are also curvilinear. In order to cut glass, 

 a diamond of this form requires to be so placed that the surface of 

 the glass is a tangent to a curvilinear edge, and equally inclined 

 laterally to the two adjacent surfaces of the diamond. Under these 

 circumstances the parts of the glass to which the diamond is applied 

 are forced asunder, as by an obtuse wedge, to a most minute distance, 

 without being removed ; so that a superficial and continuous crack 

 is made from one end of the intended cut to the other. After this, 

 any small force applied to one extremity is sufficient to extend this 

 crack through the whole substance, and successively across the whole 

 breadth of the glass. For since the strain at each instant in the 

 progress of the crack is confined nearly to a mathematical point at 

 the bottom of the fissure, the effort necessary for carrying it through 

 is proportionally small. 



The author found by trial that the cut caused by the mere passage 

 of the diamond need not penetrate so much as -i-forth of an inch. 



He found also that other mineral bodies recently ground into the 

 same form are also capable of cutting glass, although they cannot 

 long retain the power, from want of the requisite hardness. 



An Account of the Discovery of a mass of native Iron in Brasil. By 

 A. F. Mornay, Esq. In a Letter to William Hyde Wollaston, M.D. 

 Sec. R.S. Read May 16, 1816. {Phil. Trans. 1816,;;. 270.] 



This mass was first discovered in the year 1784 by a person of the 

 name of Bernardino da Mota Botelho, while looking after his cattle ; 



