40 On the Efficacy of Paragreles. 



32°. The decomposition then of a single cubic inch of wa- 

 ter will reduce the temperature of 5.85 pounds from 72° to 

 32°. But it is very improbable that the temperature of the 

 clouds should be so high as 72° at their usual elevation. If 

 we suppose their temperature to be 54°, which is likely to be 

 nearer the truth, though still perhaps too high, the decompo- 

 sition of a cubic inch of water will cause the temperature of 

 10.58 pounds to fall to the freezing point. 



The same fact may be illustrated, more forcibly perhaps, in 

 the following manner : the combustion of one ounce of hy- 

 drogen will raise the temperature of an equal weight of wa- 

 ter 23400° of the centesimal scale,* equal to 42120° F. But 

 an ounce of hydrogen, uniting with eight ounces of oxygen, 

 will form nine ounces of water. The latent heat therefore 

 of the gases which combine to form one ounce of water, will 

 raise the temperature of an equal weight of that fluid 4680°: 

 or will raise the temperature of one hundred and seventeen 

 ounces from 32° to 72°. The decomposition of a single 

 ounce of water, therefore, will reduce the temperature of 

 9.75 pounds from 72° to the freezing point.! We think then 

 that the frequent explosions of a highly charged cloud must 

 soon reduce its temperature to the point of congelation, and 

 even below this ; and consequently the fluid particles will be 

 changed into the solid state. 



If there be any truth in the above theory of the formation 

 of hail, it will follow, that the most violent hail storms will be 

 attended by the most frequent and powerful explosions of 

 electricity. Such appears to be the fact. Further observa- 

 tion may reduce this to great probability, if not to certainty. 



Z. 



Oxford, Ohio, Nov. 23, 1827. 



* Biot, Tom. 4, p. 716. 



t We were curious enough to examine whether the results from the different 

 tables of Biot referred to, would coincide ; and we found that for the decom- 

 position of a cubic inch of water, the table of page 716 gave a reduction of tem- 

 perature of only 5.64 pounds from 72° to 32°. We suspected that perhaps Biot 

 had not subtracted the water formed by the combination of the gases, from the 

 whole quantity received from the calorimeter ; and bringing this conjecture to 

 the test by taking from the three hundred and twelve pounds, nine, formed by 

 the union of the oxygen and hydrogen, the remainder gave a reduction of tempe- 

 rature of 5.68 pounds from 72° to 32° for the decomposition of a cubic inch of 

 water. The almost perfect agreement of this weight with the former, proves to 

 a high degree of probability that our suspicion is well founded ; and conse- 

 quently there'is a slight error in excess in our reasoning, on the supposition, that 

 three hundred and twelve pounds of ice were melted by the combustion of one 

 pound of hydrogen. The quantity should be three hundred and three pounds^ 



