Dr. Stenhouse on Fraxinine. 501 



only Mvas found in the calcite ; small masses of the species are 

 often completely imbedded in the accompanying pyroxene. This 

 pyroxene is massive, crystalline, and atFords cleavage prisms 

 having the ordinary angles of the species ; in a crevice it was 

 observed in small crystals. Hardness = 6-5 ; density 3-186 to 

 3-192. Lustre vitreous, pearly on the cleavage surfaces; colour- 

 less or grayish-white ; translucent to semitransparent ; fracture 

 uneven, subconchoidal. Before the blowpipe the grayish por- 

 tions become colourless ; it retains its transparency and lustre, 

 and fuses with some difficulty, and with intumescence, into a 

 colourless glass. The results of two analyses were as follows : — 



Silica 51-50 50-90 



Alumina ..... 6-15 \ 6-77 



Peroxide of iron . . ' -35 J 



Lime 23-80 23-74 



Magnesia 17-69 18-14 



Loss by ignition . . . 1"10 '90 



100-59 100-45 



This pyroxene is peculiar from the amount of alumina, which 

 has not hitherto been observed in any considerable quantity 

 except in the dark-coloured ferruginous varieties. The alumma 

 in these is supposed to replace a portion of silica, and admittuig 

 a similar relation in the present variety, wc have the ordinary 

 formula of pyroxene. The silica of the first analysis (810^ = 

 45-3) corresponds to 27-28, and the alumina to 2-87 of oxygen 

 = 30-05 ; while the oxygen of the other constituents, including 

 the water, amounts to 14-95. The ratio of 30-05 : 14-95 is very 

 nearly 2 : 1, conducing to the formula (Si 0^, AP 0^)% (MOf . 



LXXIX. On Fraxinine, the crystallizable jmnciple in the Bark 

 of the Fraxinus excelsior, or Common Ash Bij John Sten- 

 house, LL.D., F.R.S* 



IT is stated in most systems of chemistry, such for instance as 

 Lowig's, Liebig's, &c., on the authority of Messrs. Keller, 

 Hcrberger and Buchner, that the bark of the Fraxinus excelsior 

 contains a neutral, crystallizable, bitter principle, to which they 

 have given the name of fraxinine. 



Their mode of extracting this principle was to treat an inlu- 

 sion of ash-bark, so long as a i)recipitatc fell, first with neutral, 

 and then with basic acetate of lead. The whole was then thrown 

 upon a filter, and the clear liciuid which i)asscd through was 

 treated with a current of sulphuretted hydrogen till all excess of 

 * Commuulciitcd by the Author. 



