564- Intelligence and Miscellaneous Articles. 



them to bo composed of 97 parts alumina, one of oxide of chrome, 

 and two parts of silica and lime ; which composition is analogous lo 

 that of the ruby. — Comptes Rendus, August, 1837, p. 325. 



THEORY OF ORGANIC COMBINATIONS. 



M. A. Laurent states that his theory of organic combinations had 

 given him the means of predicting beforehand, the existence of cer- 

 tain compounds which have since been obtained j and that he has 

 also been able, knowing the composition of a body, to arrive without 

 doubt at the process by means of which it may be obtained. In proof 

 of the latter, he cites the preparation of cenanthic acid, and that of 

 the aether of this acid*, which he had been able to predict without any 

 other data than the composition of the acid, and without any other 

 guide than the laws laid down in the theory which he had submitted 

 to the judgement of the Academy. — Comptes Rendus, August, 1837, 

 p. 212. 



A NEW ORGANIC ACID. 



M. Peligot has read to the Academy of Sciences some observationa 

 on cane sugar, and on a new acid derived from the action of alkalies 

 on sugar of starch. 



It is well known that there exist two distinct varieties of sugar : 

 one of them is common sugar, extracted from the cane, beet-root, and 

 the maple ; the other occurs in grapes and diabetic urine, and is formed 

 when starch, lignin, or sugar of milk is treated with dilute sulphuric 

 acid. It is also known that, influenced by various circumstances, com- 

 mon sugar may be converted into sugar identical with that of starch. 



Among the differences which exist between the two kinds of sugar, 

 one of the most prominent (says M. Peligot) is in my opinion that 

 which is observed when these bodies are put in contact with alkaline 

 bases. 



Common sugar, when added to potash, lime, or barytes, combines 

 with these bases, and acts towards them the part of a true acidf : by 

 boiling a mixed solution of barytes and sugar, I obtained by direct 

 action a crystallized compound of these two bodies j the analysis of 

 saccharate of barytes, and other analogous salts, proves that the sugar 

 does not undergo any particular modification : on decomposing the 

 saccharates by weak acids, the sugar reappears with its usual properties. 



The case is entirely different with sugar of starch j the alkalies effect 

 an essential alteration in it. On putting lime or barytes into a solu- 

 tion of this sugar, even cold, 1 observed that after a certain time these 

 bases had lost their alkaline properties, and were saturated with a 

 new and very powerful acid, which is formed by simple contact with 

 the sugar, and which immediately unites with the alkalies, and forms 

 perfectly neutral salts. This acid may be still more readily obtained 

 by putting dry sugar of starch, fused at 2 12°, in contact with crystal- 

 lized hydrate of barytes. Vivid reaction takes place almost immedi- 

 ately; the mixture swells, the temperature rises very much, and in a 



* See Lond. and Edinb. Phil. Mag., vol. x. pp. 417, 418, 422. 

 f See the present volume, p. 152. 



