POPULAR MISCELLANY. 



35 



has not had an opportunity to investigate 

 his hypothesis, but he makes a few state. 

 ments that illustrate how apparently small 

 this potential may be. " To raise a single 

 pound of water," he says, " in the form of 

 vapor from the sea or from moist ground, 

 requires an amount of work equal to that of 

 a horse for about half an hour. This is 

 given out again, in the form of heat, by the 

 vapor when it condenses ; and the pound of 

 water, falling as rain, would cover a square 

 foot of ground to the depth of rather less 

 than one fifth of an inch. Thus, a fifth of 

 an inch of rain represents a horse-power for 

 half an hour on every square foot ; or on a 

 square mile, about a million horse-power 

 for fourteen hours. A million horses would 

 barely have standing-room on a square mile. 

 Considerations like this show that we can 

 account for the most violent hurricanes by 

 the energy set free by the mere condensa- 

 tion of vapor required for the concomitant 

 rain. Now, the modern kinetic theory of 

 gases shows that the particles of water- 

 vapor are so small that there are somewhere 

 about three hundred millions of millions of 

 them in a single cubic inch of saturated 

 steam at ordinary atmospheric pressure. 

 This corresponds to l /ieoo or so of a cubic 

 inch of water i. e., to about an average 

 rain-drop. But if each of the vapor par- 

 ticles had been by any cause electrified to 

 one and the same potential, and all could be 

 made to unite, the potential of the rain-drop 

 formed from them would be fifty million 

 million times greater. Thus it appears that 

 if there be any cause which would give each 

 particle of vapor an electric potential, even 

 if that potential were far smaller than any 

 that can be indicated by our most delicate 

 electrometers, the aggregation of those par- 

 ticles into rain-drops would easily explain 

 the charge of the most formidable thunder- 

 cloud." 



How an Iron-Ore Bed was formed. 



Professor James P. Kimball, of Lehigh 

 University, has published in a single pam- 

 phlet two papers on the iron-ores of the 

 Juragua Hills, of the province of Santiago, 

 Cuba, beds of a hematite or specular ore, 

 which appears to be largely the result of 

 the weathering of the highly basic rock 

 which gives the geological character of the 



formation. These rocks, the eruptive ma- 

 terial which gave origin to the iron-ore, 

 consisted of proto-silicates, or silica com- 

 bined with the protoxide bases, iron, lime, 

 and magnesia, and with alumina. Under its 

 new conditions at and near the surface, with 

 access to oxygen in the atmosphere, circu- 

 lating waters, etc., the protoxide of iron 

 became rapidly further oxidized into ferric 

 or sesquioxide, which is a comparatively 

 stable product under conditions prevailing 

 at the surface. The oxidation of the fer- 

 rous to ferric oxide is attended with more 

 or less complete dismemberment of the 

 eruptive rock, little by little. Silica origi- 

 nally combined with the ferrous oxide is 

 isolated as silica. Silicates of lime, mag- 

 nesia, and alumina form new aggregates 

 among themselves. Soluble matter as fast 

 as isolated enters into solution in circulat- 

 ing waters, and is thus at hand to assist 

 in the work of weathering. This work of 

 alteration has gone on until a complete 

 change has been wrought not only in the 

 composition but also in the arrangement of 

 the original eruptive rock. By the law of 

 molecular attraction a process of concentra- 

 tion has gone on simultaneously with the 

 process of weathering decay. Homogene- 

 ous material, such as ferric oxide, was col- 

 lected by itself to a degree far greater than 

 the other earthy residues, because, in the 

 process of conversion from ferrous to ferric 

 oxide, it has been in solution, and so in cir- 

 culation, and has hence become finally de- 

 posited under long - prevailing conditions 

 of uniform circulation. The process here 

 briefly followed out has gone on just below 

 the surface, within the range of the circu- 

 lating waters. The same action immediately 

 at the surface is followed by waste or diffu- 

 sion of the products of alteration. In the 

 present case, the best of the ore-bodies are 

 mainly, if not indeed wholly, replacements 

 of coralline limestone. 



Jnles Verne as a Scientific Authority. 



The " Revue Scientifique " discusses a curi- 

 ous question in giving its estimate of the 

 value of Jules Verne as a scientific writer. 

 It considers the judgment, which many of 

 us are ready to give, that such science as is 

 inserted into the framework of a romance 

 is worse than no science at all, as too severe. 



