Method of extracting Gelatine from Bones, 17 



The deflexion of a beam at the time of fracture, is directly 

 as the length, and inversely as the depth. 



ror then, W is as -f— • 



Definition. " The stiffness of bodies is measured by their 

 resistance at an equal linear deviation from the natural position." 

 (Young's Nat. Phil. vol. ii. art. 332.) 



The stiffness of a rectangular prismatic beam, is directly as 

 the breadth and cube of the depth, and inversely as the square 

 of the length. 



Since C D is as ^^, by multiplication BD' x CD is as L^W, 

 and by division — — — is as W ; but by the definition C D is 



hprfifnrp 



a constant quantity, therefore -j-- is as W, or as the stiffness of 



the beam. 



Several experiments were made ; but the one described was 

 preferred, because the difference in the length of the pieces was 

 greater than in the others. 

 I am. 



Your most obedient servant. 

 Red Barn, June 2, 1815. T. T. 



VIII. Report on M. D'Akcet's Method of extracting Gelatine 

 from Bones, and on its Application to various ceconomical 

 Purposes. By Messrs. Leroux, Dubois, Pelletan, Du- 

 MERiL, and Vauquelin*. 



JVl. D'Arcet has presented to the Philanthropic Society some 

 gelatine extracted from bones, by a process which is peculiarly 

 his own, inviting them to employ this substance in the broths 

 and soups which they distribute to convalescents and to the 

 poor. 



The Society accordingly nominated a commission, to inquire 

 into the advantages that may be derived from gelatine prepared 

 in M. D'Arcet's manner. After several conferences, in which 

 they were assisted by persons distinguished in chemistry and do- 

 mestic ceconomy, they were at length satisfied that the use of 

 this substance would afford a considerable saving, and of the 

 possibility of roasting for the nourishment of convalescents the 

 greatest part of the meat that is otherwise employed in making 

 the broth. 



But as the Society never adopt any new article of food 



* From the AnnaJrs de Chimie. 



Vol.46. No. 207. J«/ylBir>, r> without 



