Natural-Philosophical Collections. 55l 



combined and rendered uncrystallizable by a peculiar yellow matter. These mo- 

 difications cease, when after a long time and much care it is either separated or 

 destroyed and crystallization takes place. 



2nd. That the yellow resinous matter which accompanies quina more than 

 dnchonia, appears to change its properties much ; this yellow matter the authors 

 succeeded in destroying, but without being able to collect it separately in a per- 

 fect state. It appears to differ from the yellow colouring of the bark, which is 

 fixed by alumina, oxide of lead, and of tin. 



3d. That this yellow matter especially influences the crystallizations. 



4th. That the most certain method of clearing the mother waters from it, are 

 the addition of turpentine, repeated precipitation and solutions in the acids, and 

 concentration by cold. 



The experiments were made by MM. Henry and Delondre, and always with 

 the same results ; they operated upon the mother waters remaining after the treat, 

 ment about two hundred thousand pounds of yellow bark, and they always sepa- 

 rated from this suspected matter the portion of quina and cinchonia, the crystal- 

 lization of which it had prevented. — Journal de Pharmacie, March 1 830. 



Aurora Borealis In the evening of the 19th, soon after sunset, as bright a 



light appeared in the horizon about the magnetic north as the crepuscule imme- 

 diately above the sun ; and as the twilight withdrew, the aurora increased in 

 Iwightness. At 9 P.M. it showed a steady flame colour, and was comprised be- 

 tween the N.W. and N. by E. points of the horizon, and about nine or ten de- 

 grees in altitude. 



At 11 o'clock a vertical line of light, whose bearing was N. by E. | E. ema- 

 nated from the aurora, and in a few minutes afterwards other corruscations ema- 

 nated from it between N.W. and N., but they often dissappeared, and rose again 

 to an altitude exceeding that of ( Cassiopeia. At a quarter before 12, seven co- 

 columns of light of various widths appeared at once, and continued several mi- 

 nutes ; the wind blowing fresh from the westward seemed to give them a slight 

 inclination from a perpendicular towards the east, and they did not finally disap- 

 pear till between one and two A.M. In the course of the evening several bright 

 meteors descended from over the aurora, and in a few hours afterwards a heavy 

 gale came on from the S.W. and continued nearly four days. This meteoric 

 phenomenon was also seen in Scotland, but from the interposition of clouds it did 

 not display any vertical columns there, only faint corruscations in the horizon. 

 Whatever gaseous quality an aurora borealis may possess, whether hydrogenous, 

 electric, or magnetic, or a mixture of any of these, here (London ?) it is very ge- 

 nerally, if not the cause, a prognostic of a strong gale of wind from some quar- 

 ter Ann. of Phil. June 1830. 



On the Difference in the Height of Spring Tides.— the first, second, and 

 third tides after the new moon on the 24th of April were considerably higher in 

 Portsmouth Harbour than the first three tides after the new moon on the 24th 

 of Blarch ; yet the new moon in March was nearer to the earth's equator than the 

 new moon in April, and of course her attraction of the water was greater than in 

 the former month : the sun in March was also nearer the earth than he was in 

 April, and his attraction proportionably greater. The moon's horizontal paral- 

 laxes in the Nautical Almanac at the time of these new moons, are the same 

 within one second, and the greatest for the year till the last day of October ; yet 

 the difference in the height of the spring tides at these times was fifteen inches 

 greater immediately after the last new moon. It would be difficult under these 

 nearly coinciding circumstances to account for this unusual swell of the tides, 

 without referring to, and taking into consideration the state of the weather, and the 

 position and strength of the wind which influenced it. In March only three- 

 fifths of rain fell here; and the evaporation was nearly as great as that of the pre- 

 sent month, and the weather remarkably calm. In April between three and four 



