NATURE ASD DECOMPOSITION OF THE FIXED ALKALIS. 323 



act a similar paft with regard to the more refined and inge- 

 nious hypothesis of Lavoisier; but in the present state of 

 our knowledge, it appears the best approximation that has 

 been made to a perfect logic of chemistry. 



Whatever future changes may take place in theory, there Metals not lika- 

 seems however every reason to believe, that the metallic bases eV^a^^dTirS" 

 of the alicalis, and the common metals, will stand in the same son yet to sup- 

 arrangement of substances; and as yet we have no good founds!"" *^*'"^' 

 reasons for ais'suming the compound nature of this class of 

 bodies *. 



The experiments in which it is said, that alkalis, metallic Air and water 



oxides, and earths may be formed from air and^vater alone, "ot/'"'^^ 5'°°^ 

 ^ •' ' solid mattera. 



in processes of vegetation, have been always made in an in- 

 conclusive manner t; for distilled water, as I have endea- 



* A phlogistic chemical theory might certainly be derended, on Phlogistic the- 

 the idea, that the metals are compounds of certain unknown bases °'^^' 

 ■with the same matter as that existing in hidrogen ; and the metallic 

 oxides, alkalis, and acids, compounds of the same bases with 

 water; — but in this theory more unknown principles would be as- 

 sumed than in the generally received theory. It would be less ele- 

 gant and less distinct. In my first experiments on the distillation 

 ■of the bases of potash, finding hidrogen generally produced, I was 

 led to compare the phlogistic hypothesis with the new facts, and I 

 found it fully adequate to the explanation. More delicate researches 

 however afterward proved, that in the cases when inflammable 

 gasses appeared, water, or some body in which hidrogen is admit • 

 ted to exist, was present. 



t The explanation of Van Helmont of his fact of the produc- Van Helmont's 

 lion of earth in the growth of the willow was completely overturned experiment, 

 by the researches of AVoodward. Phil. Trans. Vol. XXI. page 1 93. 



The conclusions which M. Braconnothas very lately drawn from Braconnot's ex- 

 his ingenious experiments, Annalesde Chemie, Fevrier 1807, page P^"°^^'^^*" 

 187, [see our Journal, vol. XVIII, p. 15.] are rendered of little 

 avail in consequence of the circumstances stated in the text. In 

 the only case of vegetation in which the free atmosphere was ex- 

 cluded, the seeds grew in white sajid, which is stated to have been 

 purified by washing in muriatic acid; but sucli a process was insuf- 

 ficient to deprive it of substances, which might afford carbon, or 

 various inflammable matters. Carbonaceous matter exists in seve- 

 ral stones, which afford a whitish or grayish pov/der; and when in 

 a stone the quantity of carbonate of lime is very small in proportion 

 to the other earthy ingredients, it is scarcely acted or. by acids. 



Y 2 Toured 



