BY J. C. BRUNNICH, F.I.C. 45 



pyrogallol, calcium carbonate, ferric hydrate and carbon 

 black. 



Experiments on these lines would te of particular 

 value in our State to such crops as sugar cane, pine apples, 

 which are continuously grown on the same soil for years. 



On the whole, soil chemistry has shown that exceedingly 

 small amounts of mineral matters dissolved in the water 

 within the soil are necessary for plant life, aided perhaps 

 to some extent by a direct solving action of the roots upon 

 the solid mineral matters. This theory had its foundation 

 in the classical experiments of Sachs (1860) in which plant- 

 roots were allowed to attack a slab of marble. Many 

 investigators adhered to the notion that the rootlets excrete 

 acids which help in the solution of the mineral matters, and 

 on this theory the determination of available plantfoods 

 in a soil by treatment with dilute watery solution of citric 

 acid, as originally proposed by Dr. B. Dyer, in 1894, is based. 

 The excretion of acids is, however, not necessary to account 

 for the solvent action of roots, as is proved bj^ the fact 

 that soils maintain their neutral reaction under cultivation, 

 although continually removing small amounts of bases 

 from the soil. Instead of the acidity increasing under 

 cultivation the watery soil solutions tend to get more 

 alkaline. The slow solvent action of water on the soil 

 particles is materially aided by the ever-present carbonic 

 acid, given off continually by the growing roots, and indeed 

 the determination of the available mineral plantfoods 

 in a soil by one of the most recent methods, consists in 

 treatment with water charged with Carbonic acid gas. 



One of the most wonderful aspects of nature is its 

 dealing on the one hand with infinitely large quantities 

 and distances quite beyond the range of human conception, 

 and on the other hand with infinitesimal minute quantities^ 

 while still holding a true balance between all. 



We know that Carbon is the principal constituent 

 of all organic tissue, and that plants obtain all their carbon 

 from the minute quantities found in the atmosphere. The 

 air contains approximately about three parts of carbonic 

 acid in 10,000 parts, or in a cubic yard of air, weighing a 

 little over 2 pounds (2.281bs.) we find only 7 grains of 

 Carbonic acid. The amount of carbonic acid varies with 

 the altitude, and at a height of 18 miles, according to 



D BOTAI. SOCIITY. 



