252 On the Propagation and Groioth 



used without injury, observing only that it has been exposed to 

 the influence of the weather for some time, and the large 

 pieces removed: watering must not be neglected, as the soil 

 is rendered more porous, and the moisture passes off rapidly. 



Many other experiments were tried, such as sowing seeds 

 in charcoal: ferns, sown directly on the surface of a pot of 

 charcoal, vegetated quickly and well. 



M. Lucas observes, that his employer, the court gardener, 

 M. Seitz, acknowledged the importance of the use of char- 

 coal, and will practise a number of systematic experiments 

 upon plants in the open air, in order that a "well grounded 

 opinion on the application of charcoal ashes in general can be 

 formed." 



Theory of M. Lucas''s Experiments on the Effect of Char- 

 coal in Vegetation. — Dr. Buckner has published an account 

 of the theory of M. Lucas's experiments in the '■'■Garten 

 Zcitung,''^ the substance of which we give below, the original 

 article occupying several pages. The experiments of M. Lu- 

 cas, detailed above, are thought by Dr. Buckner to be very 

 important contributions to vegetable physiology and dietetics, 

 and his remarks are made with a view to introduce a clear sci- 

 entific notion of the effects of charcoal on vegetable life. 

 These effects are founded, undoubtedly, on several laws, of 

 which the following appear the most important. 



1. Absorption of light and generation of heat. — It is well 

 known that bodies receive the light of the sun more perfectly, 

 the darker, duller, and looser they are, and the consequent de- 

 velopment of heat is in proportion to the absorption of light. 

 As charcoal dust is one of the darkest, dullest, and most po- 

 rous of bodies, it must, on account of its peculiar capacity of 

 receiving the sun's light and changing its heat, be particularly 

 favorable to vegetable life. 



2. Absorption of atmospherical air. — Among all porous 

 bodies that have the capacity of absorbing gases and vapors, 

 charcoal has been proved, by numerous experiments, to hold 

 the first rank. Modern physiologists are, for the most part, 

 of opinion that plants can receive no solid nourishment from 

 the earth, that is, that every thing they can assimilate (or di- 

 gest) must be in a liquid and gaseous or vapory state. If we, 

 therefore, meet with silicious earth, chalk, magnesia, oxide of 

 iron, in short such substances in plants as could only be re- 

 ceived from the soil, we may always consider it certain that 



