OF ARTS AND SCIENCES. 127 



" That the ashes of corn-starch and farina are chiefly composed 

 of alkalies, and give little or no reaction for carbonic acid. 



" That all the ashes contain iron. The ash of Corn-Starch No. 1 

 also gave a distinct reaction for manganese. 



" Finally, as different specimens of the same article of food may 

 differ in constitution on account of variety in the soil or in the mode 

 of preparation (which latter was probably the cause of the marked 

 difference between the two specimens of corn-starch), these determi- 

 nations cannot be taken as giving an absolute standard of nutritive 

 value, but only as affording a probable index of results and a means 

 of comparison of the nutritive powers of each." 



Professor Horsford also exhibited specimens of the metal 

 Aluminum, to show its malleability, silver lustre, and other 

 physical properties. It was first obtained by Sir Humphrey 

 Davy, and has recently been prepared by Wohler's method on 

 a more extended scale by Deville of Paris. It is obtained 

 from common alum most conveniently, from 100 parts of 

 which about 5.78 parts of aluminum can be obtained by a very 

 expensive process ; it is made by decomposing the chloride of 

 aluminum by potassium or sodium. Its weight is 2.56. 



Professor Gray presented the following paper, entitled, 

 " Characters of New Genera of Plants, mostly from Polynesia, 

 in the Collection of the United States Exploring Expedition, 

 under Captain Wilkes (continued)." 



" ACICALYPTUS, Nov. Gen. Myrtacearum. 



" Calyx subulseformis, acute tetragonus, clausus ; apice subulato- 

 rostrato operculiformi sub anthesi circumscisse deciduo ; fauce ultra 

 ovarium longe producta. Petala 4, in operculum leviter cohserentia, 

 sub anthesi dejecta. Stamina plurima, discreta, margini calycis tubi 

 inserta : filamenta filiformia ; antherse biloculares, loculis ovalibus. 

 Stylus filiformis : stigma obtusum. Ovarium biloculare, dissepimento 

 tenui. Ovula in loculis 8 - 10, anatropa, subcurvata .'* (Fructus 

 ignotus, forte carnosus indehiscens.) — Arbor vel arbuscula ; foliis 

 oppositis ovatis penninerviis impunctatis ; floribus cymosis terminalibus. 



" AcicALYPTUS MYRTOiDES. — Fccjee Islands. 



