328 ' SCIENTIFIC NE^V^. 



ric acid were uncombined ; for there is no substance irf 

 nature which is more strongly attractive of water. 

 Mcasuteof the M. Berthollet has established a method for ascertaining 

 l^tyTndiffer\"t *^® d«^'gree of acidity of the acids, and of the alcaliiiity of 

 acids compared the different bases, by the quantity required of each to 

 together. saturate or completely neutralize the other, so as to giva 



no sign of either acid or alkaline qualities. 



He confirms this method by shewing that the propor- 

 ^ tions of these quantities are constant, and that if, for 

 example, it be necessary to add to any base twice as much 

 of any species of acid to saturate it as to saturate ano-' 

 ther base, the former of these two bases will require twico 

 as much of any other species of acid lor its saturation as 

 the second will require. 

 Combinations But the degree of resistance to heat does not correspond 

 heatmore rea- ^^^^ *^^^ force, and it is more easy for example, to de- 

 dily when wa- compose the carbonate of magnesia than that of lime, by 

 ter is present. ^^.^^ though the affinity of these two earths for the acid is 

 nearly the same. This difference arises from the much 

 greater quantity of water in the first carbonate ; and other 

 experiments shew that water favours the disengagement 

 of carbonic acid. 

 Extensive The consequences of these facts, Avith regard to all the 



Qf^th?s"^do^- ^r^^^c^^s of chemistry, particularly the theory of analysis 

 trine. are very important. The tables of affinities and great 



part of the analyses hitherto made arc shaken, and experi- 

 ment proves in fact that most of these TC5Sults demand 

 further revision. For examplcj Klaproth', and after him 

 Vauquelin have found one fifth of fluoric acid in the topaz 

 where it was never suspected. This stone must therefore 

 be ranged among acidiferous substances. Another mine- 

 ral hitherto considered as a stone, namely the t)isanite, 

 must be ranged among the metals ; (for which see our 

 present number) and various other instances no less strik- 

 ing and important, are given by the reporter. 



_,. - , M. Fourcrov has given an account of his experiments 



History of the *' " r i i i i i. 



late discoveries on platina, with an history of what has been done by 



on pbtica. others. Of this last, in abridgement, I give the substance 



without undertaking to examine into the facts and dates 



myself. 



DescotiU attempting to discover the cauise of the diffei-- 



ent 



