142 Intelligence and Miscellaneous Articles. 



nor is it when cold at all acted upon by it. From his numerous 

 researches Mr. Rose draws the following conclusions : many ox- 

 ides, and many chlorides whose oxides form bases, can combine with 

 ammonia, but there are some which do not possess this property 

 although they resemble the former class in many points. When an 

 anhydrous salt unites with ammonia it always forms a determinate 

 compound. Salts which agree in many of their properties absorb 

 ammonia often in the same, very often also in different proportions, 

 so that the combinations of anhydrous salts and ammonia do not come 

 under any law so constant as to admit of an cl priori calculation of 

 their relative proportions in a compound. Ammonia acts with an- 

 hydrous salts and the metallic chlorides analogous to them, as an 

 extremely feeble base, abandoning almost the whole of them, mostly 

 or altogether, when they are exposed to the air, or a very gentle 

 heat : the only exceptions are combinations with perchloride and 

 perbromide of mercury which do not give off ammonia when heated, 

 which property necessarily places them amongst a particular class 

 of ammoniacal compounds. 



The combinations of ammonia with the oxacid anhydrous salts 

 and the analogous metallic chlorides present a striking resemblance 

 to the compounds which the same salts form with water. Thus water 

 does not combine with all salts, and even amongst those whose pro- 

 perties are extremely analogous some will be found containing and 

 others not containing water. Thus chloride of calcium absorbs a 

 large quantity of ammonia whilst chloride of barium combines with 

 none ; sulphate of lime also unites with water of crystallization, 

 whilst sulphate of bary tes does not contain any. Besides, the water 

 of crystallization exists in a determinate proportion in all its com- 

 binations with salts; yet salts possessing very similar properties often 

 combine with very different proportions of water. Finally, water in its 

 combination with salts maybe considered as a base, although a very 

 weak one, and which can be usually expelled by a moderate heat.*— 

 Jour, de Phar., Jan. 1837. 



ON THE OXALHYDRJC ACID OF M. GUFJilN. 



M. Erdmann of Leipsick considers that the composition of the 

 acid obtained by the treatment of sugar (acide oxalhydrique of 

 M. Guerin, artificial malic acid,) is the same as tartaric acid; for if 

 a solution of this acid is allowed to stand for some time it is con- 

 verted into common tartaric acid, the oxalhydrates are converted 

 into common tartrates, and the crystallized oxalhydrate of am- 

 monia described by M. Guerin is a tartrate of that base. A further 

 examination has proved that this acid is identical with the isomeric 

 tartaric acid of M. Braconnot obtained by the fusion of common 

 tartaric acid. M. Liebig has procured well-formed crystals of tar- 

 taric acid from an acid syrup remaining after the preparation of 

 oxalic acid from sugar and nitric acid which had been left to it- 

 self for a length of time. These researches will remove all the ano- 

 malies of the oxalhydrates ofM. Guerin. — VInstitut, April, 1837- 



* See Professor Graham on this subject, Lond. and Edinb. Phil. Mag., 

 vol. vi. p. 327, et seq., vol. vii. p. 400. 



