206 



Analyses of Booh. 



[Maech, 



also lead to niucli curious information in regard to the former 

 physical and geographical distribution of plants and animals, to 

 the changes which the animated world in general^ and particular 

 genera and species, have undergone^ and probahly are still 

 undergoing ; and he would naturally be led to speculate on the 

 changes that must have taken place in the climate of the globe 

 during the various changes and revolutions. The writings of 

 Blumenbach, Von Hoti, Cuvier, Brongniart, Steffens, and other 

 naturalists, are proofs of what has been done by following up the 

 views of Werner, 



In consequence of the pressure of matter this month we are obliged to defer^ till 

 our nest number^ the continuation of the Report on Vaccination. 



Article YIII, 

 Analyses of Books. 



{Continued from No. I, p. 63.) 



Philosophical Transactions of the Royal Society of London 

 for the year 1812.--PartIL This part contains the following 

 papers : — 



Xn. Observations of a Second Comet, with Remarks on its 

 Construction. By William Herschel, LL.D. F.R. S. 



XIII. Additional Experiments on the Muriatic and Oxy- 

 muriatic Acids. By William Henry, M.D. F.R.S. V.P. of 

 the Lit. and Phil. Society, and Physician to the Infirmary at 

 Manchester.] Dr. Henry, in the year 1800, had published an 

 interesting paper in the Philosophical Transactions, on the change 

 produced upon muriatic acid gas standing over mercury, by 

 passing electrical shocks through it. The result was the evolu- 

 tion of hydrogen gas, and the conversion of part of the mercury 

 into calomel. These changes he ascribed to the decomposition of 

 water contained in the gas. The quantity of hydrogen gas 

 evolved could not be made to exceed a certain proportion. This 

 he ascribed to the complete decomposition of all the water con- 

 tained in the gas. The effect would cease of course when the 

 cause was removed. The object of the present paper is to cor- 

 rect some mistakes into vv^hich he had fallen, and to state the re- 

 sults of a repetition of the experiments with a more perfect ap- 

 paratus. The following are the facts contained in the paper. — 



1. The quantity of hydrogen evolved from muriatic acid gas, 

 by electricity, is the same whether the gas be exposed to the 

 action of dry muriate of lime or not. 2. No heat is evolved by 

 exposing dry muriate of lime to muriatic acid gas, 3, The 



