2'i6 Intelligence and Miscellaneous Articles. 



parts heated with 400 of nitric acid, gave 15-42 mucic acid and oxalic 

 acid. 



The soluble part, or arabin, of this gum gave by analvsis : 



Carbon 43 46 



Oxygen 50-28 



Hydrogen 6-26 



100-00 

 It is therefore evident that it is identical with arabin. 



The insoluble portion of Bassora gum consists of bassovin mixed 

 with phosphate of lime, silica, oxide of iron, and magnesia. 



Gum Tragacanth. — Itssp.gr. is 1'384 ; when heated to between 

 125'^ and 145°Fahr., it is more easily powdered than at common tem- 

 peratures. It swells prodigiously when put into water, and when boiled 

 in water and treated with iodine, starch is shown to be present. 



It is composed of 



Arabin 53-30 



Bassorin and starch.. 33-10 



Water 11-10 



Ashes 250 



10000 

 Jnn. de Chim. et de Plujs. xlix. p. 248. 



TRANSIT OF MERCURY OBSERVED AT GENEVA. 



This interesting phaenomenon was observed at Geneva by M. Gau- 

 tier, on the 5th May, with a telescope of DoUond's, of 3^ inches 

 aperture and 3^ feet of focal length. The power used was 72. The 

 clock, one of Skelton's, was regulated to mean time at Geneva, and 

 was about seven seconds fast. 



h m s 



Mercury entered the Sun's disc at 9 24 57 



Mercury had wholly entered on the disc at. . 9 27 40 

 First contact at the egress of the planet. ... 4 10 17 



Final contact 4 13 28 



"The planet did not appear very distinct at the moment of its en- 

 trance, but it became so afterwards, particularly with a power of 135, 

 and it presented a black and round disc, which was visible on a sheet 

 of white paper placed before the eye-glass of the telescope without 

 a darkening glass. M. Wastmann, who observed with a telescope of 

 Fraunhofer's, of 30 lines aperture and a power of 1 20, threw the sun's 

 disc upon paper, and observed that the disc of the planet was not 

 black, but of a very distinct reddish violet colour, and without any 

 penumbra. M. Eynard Chatelain measured the diameter of Mercury 

 near the middle of the transit with a Troughton's micrometer adapted 

 to a Ilamsden's telescope of 27 lines aperture, and found it about 

 1 1| seconds." — Bibl. Vnivers. April 1832, p. 431, 432. 



