j^9$ M. Kupffer's Memoir on the Specific Gravity 



Braconnot, is a mixture of seventy parts of marine salt, and 

 ^irty of chloride of potassium. Evaporated when it comes 

 put of the cylinder, after being seasoned with herbs or with 

 the juice of meat, we obtain either cakes of gelatine or cakes 

 of soup. Their uses are numerous, and it is easy to perceive 

 all the advantages of this most salubrious alimentary substance. 

 The fat contained in the bones turns into soap very quickly 

 when it is exposed to the action of compressed steam- It is 

 advantageous to take off the fat with boiling water, or even 

 at a lower temperature, because the fat is much better if 

 exposed to a low heat. The bones give out their fat very 

 quickly in steam a little condensed ; but the quantity of fat 

 changed into soap, and which remains in insoluble combina- 

 tion with the lime, rises to four or five centiemes weight of 

 bones, and such a loss ought to be avoided. 



An apparatus composed of four cyhnders is established at 

 the Hospital de la Charite. Each cylinder is 1™ in height, 

 and 0"", 333 in diameter, and contains about 40^^ of bones, 

 furnishing about a thousand basins of soup per day. 



The importance of the work of M. D"*Arcet has induced 

 us to give an abstract of the principal part of it. For farther 

 details, we must refer our readers to the original memoir, 

 printed in the Annals of Industry for February 1829. 



Art. XIII. — Abstract of M. Kupffer''s Memoir on the Specific 

 Gravity of Metallic Alloys and their Melting Points. 



In Kastner's Archiv. torn. vii. p. 331, M. KupfFer has shown 

 that alloys have always a specific gravity less than the calcu- 

 lated specific gravity, that is, that they dilate in mixing, and 

 that the value of this dilatation reaches its minimum when they 

 are united in a proportion which approaches nearly to that of 

 two atoms of tin to one atom of lead. More recently he has 

 found that the amalgams of tin experience a considerable con- 

 traction, which always diminishes, beginning with the amalgam 

 composed of two atoms of tin and one atom of mercury, and 

 which ends by becoming very small in an amalgam of one atom 

 of tin and two atoms of mercury. By increasing the number of 

 atoms of mercury the contraction increases again, so that in the 



