1<)2 ALUMINE IN METEORIC STORES. 



but very little alum, while the second and third produced 

 more. This alum comports itself in the fire like that of the 

 shops. It swells up, and assumes a reddish tinge, owing to 

 the martial vitriol it contains. 

 Proportions of These comparative experiments show, that the propor- 

 the component tions of magnesia and alumine in meteoric stones are not 

 ««pt the silex. a l wa y 9 tne same. Those of iron varying too, it is not possible 

 to determine precisely the quantity of these different sub- 

 stances, that make part of the aerolites : but the silex pretty 

 uniformly afforded me half the weight of the meteoric stone, 

 of which sulphur constitutes only a thirtieth. 

 Treatment The existence of alumine in meteoric stones being con- 



wnh sulphuric firmed by means of vitriolization, which likewise detects the 



acul necessary J 



to a perfect presence of this earth in hornblende; though it escapes us, 



analysis. when we proceed to the analysis of these substances by 



means of caustic alkali, since the able chemists I have cited 

 make no mention of it ; it is necessary, for the purpose of 

 ^in accurate analysis, to have recourse to the two methods. 



gil ex# The silex, or quartz in a state of division, mentioned as an 



integrant part of most stones, may be nothing, in many 

 cases, but the result of the decomposition of ig-neous salts 

 with base of natron, the fixed alkali of tartar having more 

 affinity with acids than natron has. 



„ , . . , The fracture of meteoric stones making known but very 



Meteoric stone . . ° 



cut and po- imperfectly the arrangement and brilliancy of the native 



listed, - ron t j ie y i nc l u de, I resolved, in order to examine it on a 



lar^e surface, to get a vase turned from an aerolite of Salles 



near Villefranche, in the Lyonese. It was found difficult to 



fafhion, because irregular splinters broke off before the 



tool; inconsequence recourse was had to the file, and to 



rubbing it dry on a plate of cast iron covered with powdered 



gritstone and emery. 



'The last polish was given with emery and Venetian tri- 

 poli, using no water, that the iron might not rust. 

 It* appearance The vase, which I offer to the inspection of the Institute, 

 iathis state, exhibits parcels of iron of irregular configurations, which 

 have a silvery lustre, intermingled with very small spots of 

 a greenish yellow, disseminated in a quartzose gangue of an 

 ashen gray. 



VI. 



