385 Perpetual Molioni-^Chemistry, 



succeeded. The inventor asserts that his plan is applicable even 

 to a man of war, and that it will secure her from the danger of 

 shipwreck. The strength of a single man, or at most that of a 

 horse, is sufficient to put the machine in motion. 



PERPETUAL MOTION. 



Another to the many supposed solutions of the problem of 

 perpetual motion has just been added by a M. Louis of Valence, 

 formerly captain in the Neapolitan service. Ke has found, he 

 says, *' means to raise a column of water strong enough to force 

 another to the same height, which produces in its turn the same 

 effect. Thus, when the impulse is once given, this machine will 

 perpetually retain its action, if there exists a fluid which does 

 not lose by evaporation, or a material indestructible by use. One 

 may, however, employ a quantity of water sufficient to keep the 

 machine in play for several years. This same machine may be 

 employed, as the impelling power, for the production of various 

 kinds of regular motions. The inventor proposes to adapt a 

 clepsydra to it, and he is convinced that, by means of a basin or 

 reservoir, a private house might derive various advantages from 



SUPPOSED IDENTITY OF PUMICE WITH LAVA, ETC. 



To Mr. Tilloch. 



May 27, 1817. 

 Sir, — On perusing an interesting memoir (in vol. xlvii. of tlie 

 Philosophical Magazine) respecting the composition of basalt, 

 trap, lava, &c. in which it is asserted that lava, basalt, and ob- 

 sidian are aggregates of pyroxdne and felspar; it occurred to me 

 that pumice may be the latter substance after having undergone 

 a, high degree of calcination. — The facts which support this 

 conjecture are the following: 



First, with respect to its constituent parts, pumice has a very 

 considerable analogy with felspar. Klaproth obtained from the 

 pumice of Lipari, 



Silica' 77-50 



Alumina 17*50 



Potassa and soda .... 3" 00 



Oxide of iron 



• of manganese . 



n-75 



9S-75 



Vauquelin found in the Adularioy 



Silica ......'. 64 



Alumina 20 



Potassa 14 



llime ...,,.. ^. 2 



Too" The 



