1820.] Scientific Intelligence^ 233 



distilled water, and the fluid then passed through filtering paper, 

 it will exhibit minute luminous jets if poured on hot water in the 

 dark. 



XII. Agave Americanum. By Mr. Murray. 



The Agave Americanum is said to flower only once in a cen- 

 tury. This much we know at any rate, its flower is a rare phe- 

 nomenon in the British isles. Not a few, however, may be seen 

 in flower on the sides of the high way from Terracina to Capuaj 

 on the road to Naples. I thiuk it obvious, from an attentive 

 examination of many of these plants, that this Agave flowers 

 only once, and that having provided for its perpetuity by an off- 

 set, the whole energies of the plant are expended in the flower, 

 which being matured it perishes. The most magnificent flower 

 of this species I ever saw was growing on an exposed rock in 

 one of the Borromean islands, called Isola madre, in the " Lago- 

 maggiore," north of Italy. I measured the flower stem, or 

 pedunculus, and found it twenty-eight and half feet in altitude, 

 and its circumference, where it emerged from the leaves, two feet 

 ten inches. It was a superb spectacle. 



I was inclined to consider this plant as indigenous to Italy, but 

 Sir James E. Smith tells me he is not of this opinion. It is, 

 however, common in that country. It crowns the xvalls of the 

 city of Genoa where it even flowers, and I have seen whole fields 

 near Pontercule fenced in entirely with the Agave Americanum. 



The plant sketched in fresco on one of the walls of Pompeii, 

 supposed to be an Agave, and which would assign a distant date 

 to its introduction into Italy, does not appear to me (and Dr. J. 

 F. Schouw joins in the opinion) ever to have been intended for 

 the plant in question. 



XIII. Crystallization of Platina. By G, B. Sowerby, Esq. 



I am not aware that any thing decided is known respecting 

 the crystallization of this substance. Bournon, it is true, has 

 mentioned some grains of platina which have a distinct form, 

 but these appear to have been a deposition of platina upon some 

 other substance which has afterwards been decomposed and 

 gone, for they are hollow and mammillated upon their outer sur- 

 faces. I have some of these, and I have reason to think that 

 they have been formed over palladium, for some externally 

 mammillated portions of platina which accompany them are still 

 adherent to native palladium. But in looking over a small 

 parcel of platina very lately, I discovered several pieces which 

 had a perfectly lamellar structure, and a distinct cleavage ; and 

 one of them which showed the four faces forming the solid angle 

 of an octahedron. I have preserved this little fragment, as being 

 perfectly demonstrative for the inspection of any who may think 

 the subject sufficiently interesting. 



Should you think this notice worthy of insertion in your jour- 

 nal, it is much at your service. 



