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A*. Refe arches on Alumine. Read Dec. J 8, 1S00, in the 

 Society of Tbyfics and Natural Hijlory at Geneva, By 

 Theodore de Saussure. 



On (be Combination of Alumine with tbe Carbonic Acid. 



I* V/NE cannot help being aftonifhed that, though moft 

 of the combinations of alumine with the acids are Known, 

 we have ftill bat imperfect notions refpe&ing the union of 

 this earth with a fubftance fo widely difTufed as the carbonic 

 acid. When defirous of repeating the experiments of 

 M. Humboldt on the abforption of oxygen gas by fimple 

 earths, I w r as induced to confider alumine in its different 

 ftates, and particularly in that in which moft chemifts con- 

 fider it as a carbonat. On this fubjecl: I have made fome 

 obfervations, which may ferve to throw new light on this 

 combination. 



Opinions of fome Chemifls refpecling the Carbonat s of Alumine. 



II. Bergman, in a difTertation on the aerian acid, fays*: 

 te Fixed air attacks pure argil with difficulty, that is to fay, 

 the earth of alum dried and hardened ; the precipitation of 

 alum, however, by aerated alkali, proves that it may take up 

 a fmall quantity when it is attenuated ; for though the liquor, 

 when well filtered, appears limpid, it is remarked that, when 

 left a few days to the open air, and a heat capable of pro- 

 moting the extrication of the fixed air, it becomes turbid, and 

 Infenfibly depofits a little earth, which was held in folution 

 by the volatile fluid. The argil of Cologne itfelf gives, in a 

 ft-rong heat, a quantity of fixed air which exceeds its volume 

 feveral times. It is mixed with a little inflammable air, 

 which rifes at the commencement of the operation. " 



Bergman then gives the proportions of the carbonic acid 

 m artificial carbonat of alumine, and finds, that ioo parts of 

 aerian acid may unite with 30 of pure alumine. 



III. Fourcroy, in his Elements of Chemiflrv, and his 

 work entitled Sjf.'me des Connoifances Chimiquesf, admits 

 atfo the combination of alumine with carbonic acid gas under 

 the denomination of carbonat: ift, According to the expe- 

 riments of Bergman; 2d, According to his own. He ob- 

 ferved that, if the precipitation of the fulphat of alumine by 

 an alkaline carbonat be made cold, little or no efTervefcence 

 is produced, becaufe, in his opinion, a part of the carbonic 



* French edition of his works, Vol. I. f Vol. IV. p. 61. 



acid 



