( 278 ) 



Perhaps we may find an explanation for tliis fact in the influence 

 no doubt exerted by the earth's mean magnetic held and the 

 distribution of positive ions in the atmosphere. 



These speculations are indeed very rough, but they have one great 

 advantage, viz. to avoid the difficulty, raised by Lord Kelvin, of 

 allowing an expenditure of the sun's energy causing magnetic disturb- 

 ances, much too great to be admitted. 



Chree (Terr. Magnet. X, p. 9) points to the fact, that also Maunder's 

 deflned streams require far too great an expenditure of energy. 



According to my opinion we have only to deal with (he charge 

 received at the moment of the impulse, and by accepting an inter- 

 mittent emission of the sun's energy, it is not necessary to integrate 

 it over the entire time between one or more returns of the stream. 



Part of the energy is also supplied by the rotation-energy of the 

 earth; and it is curious to remark, that by such an influence the 

 rotation of the earth would be lengthened for a minute fraction 

 during a magnetic storm. 



Chemistry. -— "titration of meta-substituted phenols" . By Dr. J. J. 

 Blanksma. (Communicated by Prof. Holleman). 



(Communicated in the meeting of September 30, 1906). 



Some years ago') I pointed out that by nitration of meta-nilro- 

 phenol and of 3-5-dinitrophenol tetra- and pentanitrophenol are formed. 

 This showed that the NO^-groups in the m-position do not prevent 

 the further substitution of the H-atoms in the o- and p-position by 

 other groups. I have now endeavoured to increase these two cases 

 by a few more and have therefore examined the behaviour of some 

 m-substituted phenols which contain, besides a NO^-group in the 

 m-position, a second group in the m-position, namely of 



C,R, . OH . NO, . (CH3,OH,OCH3,OC,H3,Cl,Br) 1.3.5. 



Of these phenols the 5-nitro-m-cresoP) and the monomethylether 

 of 5-nitroresorcinoP) were known. The still unknown phenols were 

 made as follows: 



The 5-nitroresorcinol (m.p. 158°) from its above cited monomethyl- 

 ether by heating for five hours at 160° with (307J HCl, or by 

 reduction of 3-5-dinitrophenol with ammonium sulphide to 5-nitro- 



1) These Proc. Febr. 22, 1902. Rec. 21. 241. 



2) Nevile en Winther Ber. 15. 2986. 



3) H. Vermeulen Rec. 25. 26. 



