Royal Society. 461 



succession of sparks, its dynamic effects on the galvanometer are the 

 same in both cases ; each spark producing a constant deflection of 

 the needle. It is hence inferred that the current, even when the 

 circuit is closed, may be regarded as a series of discharges of elec- 

 tricity of tension, succeeding each other with infinite rapidity. 



5. In a battery, of which the chemical elements have but a feeble 

 mutual affinity, as is the case with the water battery, the tension rises 

 very slowly. 



6. In order to produce static effects in the voltaic battery, it is an 

 indispensable requisite that the elements be such as are capable of 

 combining by their chemical affinities : and the higher those affini- 

 ties are exalted, the smaller is the number of parts composing the 

 series requisite to exhibit the effects of tension. The static effects 

 elicited from a voltaic series, afford, therefore, direct evidence of the 

 first step towards chemical combination, or dynamic action. 



The author observes, in conclusion, that the chemical effects, when 

 obtained in most of the experiments he has described in this paper, 

 are very feeble ; but are precisely the same in character as those ex- 

 hibited by the more powerful voltaic combinations ; and he thinks 

 it may fairly be concluded that the rationale of each is the same, and 

 that they differ only in the amount of action. 



February 15. — " Some further Observations and Experiments 

 illustrative of the Cause of the Ascent and continued Motion of the 

 Sap," in continuation of a Paper presented to the Royal Society in 

 November 1842. By G.Rainey, Esq. Communicated by P.M.Roget, 

 M.D., Sec. R.S. 



The author here gives an account of some experiments which he 

 has lately made, tending, in his opinion, to corroborate the opinions 

 he advanced in his former paper; namely, that the ascending sap is 

 situated in the intercellular and intervascular spaces of the plant, and 

 that its passage into the cells is effected by the action of endosmose, 

 which the intervening membranes, whether living, or deprived of 

 vitality, exert upon that fluid. He found that portions of many plants, 

 such as Anthriscus vulgaris, and the Lapsana communis, absorb a 

 much larger quantity of fluid when they are immersed in pure 

 water, than when similarly immersed in a solution of gum-arabic ; 

 and that, in the latter case, the remaining portion of the solution is 

 of the same specific gravity as before any part has been absorbed by 

 the plant. By a similar process, the author conceives, the fluid which 

 is derived from the earth, and has passed into the intercellular spaces 

 of the cotyledons, are imbibed by its cells by endosmose ; while at 

 the same time a fluid containing sugar is passing, by exosmose, out 

 of these cells into the intercellular and intervascular tissue, and thence 

 into the corresponding tissue of the peduncle and young stem ; it 

 there meets with, and is diluted by the water ascending in the same 

 tissue from the roots, and the mixture is afterwards distributed over 

 every part of the plant. 



February 22. — " On the Temperature of the Springs, Wells and 

 Rivers of India and Egypt, and of the Sea and Table Lands within 

 the Tropics ; with a few Remarks on M. Boussingault's mode of as- 



