218 



Messrs. J. H. Gladstone and A. Tribe on the [Mar. 14, 



evidence now deduced as to a connexion of some sort between the behaviour 

 (^of sun-spots and the positions of the planets Venus and Mercury. We 

 think, however, it must be allowed, that the investigation is one of interest 

 and importance, and we trust that arrangements may be made for the 

 systematic continuance of solar observations in such localities as will ensure 

 to us a daily picture of the sun's disk. 



The influence of blank days in diminishing the value of a series of sun- 

 observations is very manifest. We have been able to record the behaviour 

 aqross the sun's disk of 421 groups of Carrington's series out of a total 

 number of 885 groups, and we have been able to record the same behaviour 

 for 373 out of 544 groups observed at Kew. Thus, out of a total of 1429 

 groups, we have only been able to record the behaviour of 794. Nor are 

 the records which we have obtained so perfect as we could wish, on account 

 of blank days, which make interpolations necessary. It is therefore of 

 much importance for the future of such researches as the present, that 

 there should be several observing-stations so placed that we may reckon on 

 having at least a daily picture of the sun's disk. 



It will be easily seen that such observations are very different from ex- 

 periments, which may be multiplied ad libitum ; for in this case Nature 

 gives us in a year or in ten years a certain amount of information, and no 

 more, while it depends upon ourselves to make a good use of the informa- 

 tion which she affords. 



It is already universally acknowledged that we ought to make the best 

 possible use of the few precious moments of a total eclipse ; but such ob- 

 servations must necessarily be incomplete unless they are followed up by 

 the equally important, if more laborious, task of recording the sun's surface 

 from day to day. 



III. t( The Decomposition of "Water by Zinc in conjunction with 

 a more Negative Metal." By J. H. Gladstone, Ph.D., 

 F.R.S., and Alfred Tribe, F.C.S. Received February 8, 

 1872. 



Pure zinc is incapable of decomposing pure water, e^en at 100° C, but 

 at a considerably higher temperature it is known to combine with its 

 oxygen. Davy exposed pure water for two days to the action of a pile of 

 silver and zinc plates, separated only by pasteboard, without obtaining 

 any hydrogen ; Buff, however, has shown that a very minute trace of gas 

 can be formed at the ordinary temperature by a pair of zinc and pla- 

 tinum plates. 



During a series of experiments, of which we have already published an 

 instalment, it occurred to us to ascertain whether by bringing the two 

 metals closer together, and so increasing the electrical tension of the liquid, 

 we could effect the lame combination of zinc with oxygen at the ordinary 

 temperature which takes place without the second metal at a very high 



