376 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



spray, allowing this to freeze, and then sprin- 

 kling again. During last winter, tubes of thin 

 sheet-iron were laid on the floating-bath on the 

 Thames, at Charing Cross, and a skating-floor 

 was frozen. The temperature of an ice-rink, from 

 its agreeable coolness, has an exhilarating and 

 bracing influence, which dissipates the languor 

 felt in a warm, moist atmosphere. 



M. Pictet's machine has interest beyond that 

 of any ordinary, economical producer of ice, for, 

 constructed as it is with all the philosophical 

 thought and scientific knowledge which we usual- 

 ly find bestowed only on instruments of research, 

 it has been applied by its inventor to the purpose 

 of establishing certain simple relations between 

 the latent heat, molecular weights, and tensions 

 of the vapors of volatile liquids. 



By the application of mathematical reasoning 

 and the use of known data, M. Pictet calculates 

 the latent heat of various liquids, and arrives at 

 the following conclusions : 



1. Cohesion is a constant quantity for all 

 liquids. 



2. The derivate of the Napierian logarithm, 

 representing the ratio between vapor-tension and 

 temperature, is constant for all liquids, when they 

 are compared under the same circumstances of 

 pressure and temperature. 



3. The latent heat of all liquids referred to 

 one and the same pressure, multiplied by the 

 molecular weight, referred to a uniform tempera- 

 ture, gives a constant product. 



4. For all liquids, the difference between the 

 latent heat at any two temperatures, multiplied 

 by the molecular weight, is a constant num- 

 ber. 



5. The latent heat of every liquid is a mul- 

 tiple of its specific heat. 



It would be entering too much into detail to 

 give the method by which these very important 

 conclusions have been arrived at, but it may be 

 of interest to some readers to know that an arti- 

 cle on the subject was published by M. Pictet in 

 the last volume of the Philosop7tical Maga- 

 zine. 



— Popular Science Review. 



SCHOPENHAUER IN A NUTSHELL. 



By F. IIUEFFEE. 



IN his" Critique of Pure Reason" the great Kant 

 has proved the absolute impenetrability by 

 our knowledge of the essence of things. Our 

 sensual and intellectual organs are not adapted 

 to such knowledge. To perceive at all we must 

 attach to the objects of our perception certain 

 conditions and relations, which in reality are the 

 functions of our own brains, making such percep- 

 tion possible. That is, in order to become aware 

 of objects, we must regard them in their sequence 

 after one another (time), in their various positions 

 of coexistence (space), and finally in their mu- 

 tual relations of cause and effect (causality). The 

 ideality (i. e., objective non-reality) of time, space, 

 and causality, taught by Kant is the final death- 

 blow of the a priori dogmatism of former systems. 

 For our intellect (using the word in the most gen- 

 eral sense), limited by the conditions alluded to, 

 can never go beyond the appearances of things, 

 the phenomena. To whatever extent the exact 

 sciences may learn the various qualities of these 



phenomena, there always remains and must re- 

 main a residuum of unknown essence, indepen- 

 dent of space, time, and causality, and unaltered 

 and undiminished after all the definable qualities 

 alluded to (for instance, in the case of matter, 

 weight, extension, etc.) have been deducted. This 

 unknown essence Kant calls the " thing in itself" 

 {Ding an sick), thus pronouncing the final and 

 total bankruptcy of human reason in matters 

 metaphysical. For what positive idea is it possi- 

 ble to connect with this or the still more nebulous 

 though grander-sounding terms wliich later phi- 

 losophers have used ? Is not the "thing in itself" 

 in reality a decorous disguise of the great un- 

 knowable, the x in the metaphysical equation of 

 the universe ? 



Schopenhauer, who thus far has in essentials 

 followed Kant, here steps in, and solves the rid- 

 dle of the sphinx by the simple formula — x = 

 Will. This transfers us at once from the indefi- 

 niteness of metaphysical terminology to the firm 



