HOLLAND SOCIETY OF SCIENCES OF HARLEM, 1869. 417 



on itself. On the otlicr liand, it may be su])posed that the intensity of the cur- 

 rent further modifies tlie value of the resistance by virtue of an action which 

 does not directly depend on the heating. It is desirable that, in one and teh 

 other point of view, the influence exerted by the intensity of the current or the 

 deforce of the resistance, should be studied. Among the metals susceptible of 

 being employed in this incpiiry, mercury would seem to be one of those which 

 offer the most advantages. 



IV. The society solicits a criticism, as well as a repetition and extension of 

 the experiments on the electrolysis of the melted haloid salts, (Faraday, Experi- 

 mental licsearches, vol. i, art. 538 ct scq. and 978 et seq.,) together with an 

 exi)osition of the considerations which are deducible therefrom (m the nature o-f 

 electrolysis. 



The law of Faraday on electrolysis is extremely simple; but the question is 

 far from being exhausted, and the ensemble of the phenomenon is as yet covered 

 with a thick veil. Hence it is especially desirable to determine to what point 

 the before-cited experiments are in opposition to that higher view, suppoiied hy 

 a great number of facts, agreeably to which no true electrolysis can take place 

 unless the action of the current is exerted on double salts or on combinations 

 which are equivalent and analogous to them. 



V. According to M. G. Ville, (see Eevuedcs Cours scknfi/iques, 1868, No. 7, 

 ]). 103,) nitrogen in a free or elementary state is assimilated by certain plants, 

 ]\arti('ularly by leguminous plants. The society wishes that this opinion should 

 be submitted to a critical examination, and that its exactness or its falsity be estab- 

 lished theoretically or experimentally, and preferably by both methods. 



VI. In regard to the experiments of M. Graham, the society calls for new 

 researches on the solutive power of melted metals for hydrogen, particnlai'ly 

 with a view to deciding whether there exist definite combinations of metals with 

 hydrogen. 



VII. The society asks for an exact description, accompanied with figures, of 

 the changes undergone by the organization of the Batrachians during their meta- 

 morphosis. 



VIII. The assertion that metals become transparent at a temperature suffi- 

 ciently elevated, requires to be confirmed or invalidated by experiments made 

 on several different metals. 



IX. The societ}' wishes to have it experimentally determined whether the 

 hnninous power of the Lampijris nocfiluca ct splendklida (Linn.) should be 

 attrilmted to the secretion of a particular matter, and if it be so, that the natiu'C 

 and composition of that matter be investigated. 



X. There still exists nmch obscurity respecting the cause of the phosplu>rescence 

 of the substances which bear the name of artificial phosphorus. The society 

 invites a thorough investigation, to the end of deciding the question whether 

 that phosphorescence should bo attributed solely to a slow oxidation. 



XI. Wliilst, in meteorological observations, the pressure and temperature of 

 the air, tlie direction and force of the wind are observed in a continuous manner, 

 by means of registering instruments, we are always reduced, as far as the humid- 

 ity of tlie air is concerned, to isolated observations made at certain hours of the 

 day. The society desires the construction, whether upon new princi})les or such 

 as have been already indicated, (see Puf/genchrff's Anmden, vol. 93, p. 343,) 

 of a registering iustrument for the determination of the humidity of the air, and 

 solicits a counuunication of the results of observations made with such an iustru- 

 ment and continued during at least half a yeai'. 



XII. A memoir on tlu; life of Koopman (Mcrcator) and of Ortels, (Ortdius,) 

 and on the services which these two savants have rendered to geography, eth- 

 nology, and cartography, is regarded as a desideratum. 



27 S 



