[ 321 j 



LIII. On the Production of Aerolites, and other Solids^ hy the 

 Union of aeriform Fluids. 



To Mr. Tilloch. 



Sir, — J. HE ingenious manner in which M. Marcel de Serres 

 endeavours to throw some light on the formation or production 

 of aeroHtes*, &c. induces me to make some remarks on the pro- 

 duction of certain soHds by the union of aeriform fluids or gases, 

 and which still further induces me to tiiink that in this branch 

 of chemistry there are many discoveries yet to be made. We 

 know that most vegetable as well as animal substances contain 

 proportions of metals, as well as earths which are now known to 

 be of metallic basis. M. Berthollet is said to have obtained 

 gold from the ashes of vegetables; and this will not appear impro- 

 bable to us, when we consider that gold is almost as general a 

 metal as iron, though in such very minute quantities. We know 

 also that iron enters into the composition of almost all of the 

 vegetable kingdom, and this undeniable experiments have proved 

 that it does from the atmosphere. Are we then to suppose that 

 they enter in the form of acidulous vapours containing the metal 

 or earth in solution, or by the union of certain gases, by which 

 means other solids of a meaner consistency are undoubtedly 

 formed ? The ingenious botanist I\!rs. Ibbetson has proved 

 that certain plants are so constructed by nature as to accom- 

 modate themselves to an unnatural soil, by certain alterations in 

 their vessels, which enable them to inhale moisture, or more 

 likely the gases by which the aqueous portion is formed: and 

 indeed we know that all plants inhale and exhale, thereby 

 forming the whole of the aqueous, mucilaginous, as well as 

 the more solid parts, by the destruction or decomposition and 

 recomposition of various gases ; and which has been proved by 

 trees being suffered to attain double the weight of the earth 

 in which they grew, while the latter was not in the least de- 

 creased. If it is argued to be from the water by which they were 

 fed, it may be again said, that water is merely a compound 

 of gases. 



It appears to me, that the principal solid constituent of vege- 

 tables may be thus formed. Since we know that moisture is 

 necessary to all vegetables, we know that by some means or 

 other it enters its parts ; and as experiment teaches us that most 

 of the resinous, mucilaginous, and gelatinous substances, which 

 all plants possess, may be decomposed into carburetted hydro- 



• Phil. Mag. Tol. xliii. p. 253. 



Vol.44. No. 199. iVbv. 1814. X gen. 



