168 Sir C. Snadwell on Terrestrial Magnetism. [June \d, 



This compound is therefore obviously produced by the following re- 

 action : — 



BEt.Ho + O = BEtEtoHo. 



Boric diethohydrate. Boric ethethylate-hydrate. 



Boric ethethylate-hydrate is a transparent and mobile liquid at ordi- 

 nary temperatures, but below 8° C. it is a white crystalline solid, which 

 has an odour like that of boric ethide and a strong pungent taste. It is 

 neutral to test-papers, and is rapidly decomposed by water, exchanging 

 its semimolecule of ethox}^ for hydroxyl, and forming boric ethodi- 

 hydrate and alcohol ; thus, — 



BEtEtoHo -H OH^ = BEtHo, + EtHo. 



Boric ethethylate-hydrate. Water. Boric ethodihydrate. Alcohol. 



Unlike boric diethethylate and boric diethohydrate, this body is not 

 spontaneously inflammable ; but, like the latter, it cannot be distilled at 

 the ordinary atmospheric pressure without undergoing decomposition. 



I am now engaged in submitting the organo-boron compounds and 

 their deriyatiyes to a thorough inyestigation, and hope shortly to have 

 the honour of laying before the Soyal Society further details respecting 

 this family of organic compounds. 



In conclusion I have much pleasure in expressing my thanks to my 

 assistant, Mr. J. M. Cameron, for the efficient aid which he has a:fforded me 

 in this work. 



XIX. "A Contribution to Terrestrial Magnetism.'^ By Vice- 

 Admiral Sir Charles Shad^vell, K.C.B.^ F.B.S. Beceived 

 June I5_, 1876. 



(Abstract.) 



In this paper the author records the results of a series of observations 

 for the "Magnetic Dip" taken during the voyages of H.M.S. 'Iron Duke' 

 in the eastern seas, visiting China, Japan, and adjacent places, in the 

 years 1871-75. 



The dip-cii'cle employed was furnished with two needles, and the con- 

 cluded dip recorded is the mean result of the observations by both 

 needles. 



The observations are sixty-six in number, taken at forty-two places, 

 opportunities ha™g been frequently afforded of repeating them on suc- 

 cassive visits to the same station. In some instances the observations 

 were repeated after an interval of from twelve to fourteen years, at sta- 

 tions formerly visited by the author on a previous visit to China and 

 Japan (1857-59), thus affording data for the deduction of the approxi- 

 mate values of the secular change of this element. Moreover some of 

 the observations having been taken at off-lying stations to the eastward 

 of the coast-line of the Asiatic continent, data have been obtained for 



