PRIZE QUESTIONS OF SCIENTIFIC SOCIETIES. 433 



17. It is of the utmost importance to theoretical chemistry to know 

 the rehitive intensity of the forces which unite one or two or more 

 equivalents of a substance to one equivalent of another. Admit- 

 ting that the heat which is disengaged when a combination is effected 

 may serve as the measure of these forces, we yet need experimental 

 research on the quantity of the heat so disengaged when one equiva- 

 lent of an element cpmbines with one or two or more equivalents of 

 another. 



18. What influence has the progress of organic chemistry exer- 

 cised upon the theory of the composition of inorganic substances? 

 With what degree of certainty can we admit the existence of radical 

 compounds in inorganic combinations ? 



19. What means of transport to the Indies, whether by the old 

 route of the Cape of Good Hope or by the proposed canal across the 

 Isthmus of Suez, may be considered the most economical for com- 

 merce — that by sailing vessels, by steamers, or by sailing vessels 

 aided by steam ? 



20. The velocity with which magnetism, in whatsoever manner 

 developed in one part of a mass of iron, diffuses itself throughout 

 the mass is not yet ascertained. The society requests that this ve- 

 locity be determined by rigorous experiments. 



21. The difference of numerical results obtained by different 

 savans as to the conducting power of different metals for electricity 

 renders it necessary that on this point there should be a new research. 

 The society, therefore, requests that there shall be a new determina- 

 tion in a rigorous manner of the relative conducting power of 

 the metals and the alloys most in use — the former in a state of chem- 

 ical purity, and the latter in exact proportions. The society desires 

 that endeavors should at the same time be made to find the law ac- 

 cording to which the conducting power of an alloy depends upon that 

 of the metals of which the alloy consists. 



22. The society requests a description of the fossil fauna of the 

 Netherland provinces, Gueldre and Overijssel, compared with that 

 of analogous formations in the adjacent countries. Should the author 

 have satisfactory reasons for so doing, he may confine himself either 

 to the vertebrate or to invertebrate animals of these fauna. 



The ordinary prize of a satisfactory reply to either of these ques- 

 tions is a gold'medal of the value of 150 florins, and a further gra- 

 tuity of 150 Dutch florins if the reply is deemed worthy of it. 



The replies, legibly written, must be made in Dutch, French, 

 English, Italian, or Latin; or in the German language in Roman 

 characters; and must be sent, 2^ost free, accompanied by sealed notes, 

 in the usual manner, to M. J. G. S. Van Breda, perpetual secretary 

 of the Holland society at Harlem. 



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