138 



M. Janssen on the Solar Eclipse of Dec. 1871. [Feb. 1, 



vatives were the same as those of the hexane from petroleum ; it must, 

 however, be stated that the boiling-points of some were a little higher than 

 those of the petroleum hydrocarbon, and there was also a marked differ- 

 ence observed between the two caproic acids. That from mannite gave a 

 well-crystallized barium-salt, whilst that from petroleum could only be 

 obtained in the amorphous state ; but as the two secondary alcohols 

 yield both normal butyric acid, the chemical constitution of the two 

 hexanes must be the same. 



(3) Dipropyl. — This hydrocarbon was prepared by acting with sodium 

 on primary propyl iodide ; boiling-point 69°-70° ; specific gravity at 

 17°=0 6630. The quantity obtained was too small for further investiga- 

 tion ; but the mode of its formation shows that it must have the same con- 

 stitution as the two other hexanes. 



Heptane or normal heptyl hydride, C 7 H 16 ; boiling-point 97°*5-99°. — 

 This hydrocarbon, which is also found in petroleum, gives a secondary 

 alcohol (boiling-point 160°-162°), which is methyl-pentyl carbinol 

 CHI 



q jj 3 [ CH.OH, as the acetone obtained from it yields on oxidation acetic 



acid and normal valerianic acid. The primary heptyl alcohol boils at 

 170°-172; on oxidizing it, oenanthylic acid, boiling at 219°-222°, was 

 formed, which was found to be identical with the acid obtained from 

 castor-oil. 



Octane or normal dibutyl, C 8 H 18 , is easily obtained by the action of 

 sodium on normal butyl iodide. It boils at 123°-125°, and has at 17° 

 the specific gravity 0*7032. As the octane from methyl-hexyl carbinol, as 

 well as that which Zincke obtained from primary octyl alcohol, have the 

 same boiling-points and specific gravities, it appears most probable that 

 these three hydrocarbons are identical. 



IV. "Note on the Eclipse of the Sun (Dec. 1871) as observed at 

 Sholoor." By M. Janssen. Communicated by the President. 

 Received January 15, 1872. 



Monsieur le President, — J'aurai l'honneur d'adresser a la Societe 

 Royale de Londres un memoire detaille de mes observations de l'eelipse, 

 mais je profite du de'part de ce courrier pour vous informer des principaux 

 resultats obtenus. 



Sans entrer dans une discussion qui fera partie de ma relation, je dirai 

 d'abord que la magnifique couronne observee a Sholoor s'est montree sous 

 un aspect tel, qu'il me paraissait impossible d'admettre ici une cause de 

 l'ordre de phenomenes, ou de diffraction, ou de re'flexion sur le globe 

 lunaire, ou encore de simple illumination de P atmosphere terrestre. 



Mais les raisons qui militent en faveur d'une cause objective et circum- 

 solaire, prennent une force invincible quand on interroge les elements lumi- 

 neux du phenomene. 



