462 Analyses of Books. [Dec. 



100 grains of ivory attract from the air 7 gr B . of humidity 



boxwood 14 



down 16 



wool 18 



beech 28 



There is little difference between the effect produced upon the 

 dryness of air by the pure earths ar.d their carbonates; but the 

 effect is greatly diminished by heating the earthy bodies red-hot. 



IV. Cold produced by Rarefaction, assisted by the absorbing 

 Power of Sulphuric Acid. — Mr. Leslie's method of freezing 

 water by placing it under the receiver of an air-pump in a small 

 vessel, while the greatest part of the bottom of the receiver is 

 occupied by a shallow vessel of sulphuric acid, and exhausting 

 the receiver, is known, I presume, to most of my readers. By 

 drawing out the air, the rate of evaporation is accelerated. The 

 sulphuric acid absorbs the vapour as fast as it is formed. Thus 

 the evaporation is continued without intermission. The cold 

 produced is sufficient to freeze the water in a very short time : 

 indeed, it is so great that Mr. Leslie has even frozen mercury 

 by means of it. Mr. Leslie describes the different experiments 

 which he has made on this curious subject at considerable length, 

 explains the theory of the congelation, points out the proper 

 methods of proceeding, and the various important purposes to 

 which the process may be applied. This part of the book is very 

 interesting, and highly deserving the attention of all classes of 

 readers. Indeed, the many valuable practical inferences which 

 the author draws in different parts of his book, and the many 

 useful purposes to which he conceives his instruments may be* 

 applied, give this little treatise a claim upon the attention of the 

 nation in general, and entitle the author to the thanks, not only 

 of men of science, but likewise of our manufacturers and agri- 

 culturists. 



The Philosophical Transactions for 1813, part ii. are pub- 

 lished : they shall be noticed in a subsequent Number of the 

 Annals of Philosophy. 



The Memoirs of the Imperial Academy of Sciences of St. 

 Petersburgh for 1809, 1S10, and loll, have been received in 

 London : they shall be likewise noticed in a future Number of 

 the Annals of Philosophy. 





