384 Proceedings of Philosophical Societies, [May, 



Bt^rthoUet^ in his elaborate remarks upon carbonic oxide, and 

 his critique upon the experiments of Clement and Desormes, 

 revived the opinion of Lampadius; and this was confirmed by 

 the experiments of Berthollet, jiin. The subject was lately 

 resumed by Ciusel, who concluded from his experiments, that 

 the substance was a triple compound of sulphur, charcoal, 

 hydrogen, and azote. Thenard examined the substance anew, 

 and found it a compound of sulphur and charcoal alone. These 

 discordant results prevent any confidence' from being put in the 

 various experiments already made. It was to remove the doubts 

 still hanging- over the subject that Berzelius and Marcet were 

 induced to undertake the investigation of the subject. 



LINNiEAN SOCIETY. 



On the 5th of April the remainder of Mr. Keith's paper on 

 the cotyledons of grasses was read. He found by examination 

 that the slieath of the plumula never assumes the form of a true 

 leaf; that it rises out of the ground, is at first white and trans- 

 parent, and then becomes purple; and that it divides, and 

 allows the leaf of the plumula to pas's through it. The secondary 

 shoots are also furnished with sheaths; but their structure is 

 quite different from that of the plumula. As to the scale called 

 vitelliLs by Gsertner, Mr. Keith conceives that it may be intended 

 to act as a strainer to the milky food prepared in the albumen. 



At the same meeting an analysis of arragonile, by the Rev, 

 John Holme^ of St. Peter's College, Cambridge, was read. 

 This mineral has been long known to mineralogists, and consti- 

 tutes an anomaly in the Haiiyan theory of crystallization. The 

 figure of its crystals, its specific gravity, its hardness and lustre, 

 difler from the same properties in calcareous spar; yet its con- 

 stituents, as far as chemical analysis has gone, are absolutely 

 the same. It has been analysed by Klaproth, Bucholz, Vau- 

 quelin, Chenevix, Thenard, and Biot; but nothing different 

 from the constituents of calcareous spar was found. Mr. Holme 

 conceives the difference to depend upon a quantity of water 

 chemically combined in arragonite, while calcareous spar is 

 destitute of that constituent. He found that when exposed to 

 heat it gives out v/ater without decrepitating, and at the same 

 time falls to powder. This water was found to contain no 

 carbonic acid gas, nor was any given out under a red heat. The 

 constituents of arragonite, according to Mr. Holme, are as 

 follows:- — 



Lime 55*5 



Carbonic acid 43*7 



Water 0-8 



100 



