114 JOURNAL OF THE 



Prof. Nessler, with loamy soil containing 18 per cent, of car- 

 bonate of lime, but with 3.4 times as much superphosphate (or 

 1 part soluble phosphate with 30 of soil), obtained like results. 



We notice from the above table: 1st. That lime causes pre- 

 cipitation more than any other element in the soil, for with the 

 largest content of carbonate of lime we have the greatest pre- 

 cipitation ; 2d. Nothing definite can be said in regard to the 

 precipitative power of the oxides of iron and alumina, for in 

 mixture 1, with a per cent, of 6.10, the precipitation is 24.29, 

 while in 3, with a content of iron and alumina nearly three 

 times as great, the precipitation is actually less. The same can 

 be said of mixtures 4 and 5, though in a less degree. 



In these experiments, however, a very large excess of water 

 was used. While in the soil merely moistening would be the 

 actual condition, we have here a volume of water about three 

 times that of the soil. It is impossible, therefore, to approxi- 

 mate by these experiments the real action on the phosphate by 

 the soil; we must necessarily have a much smaller quantity of 

 water for the experimental mixing. 



II. Wagner, in 1877,* records the following experiments. 

 In these the amount of water is much smaller than the forego- 

 ing, and much uearer represents what might actually be said to 

 take place in the soil : 



Twenty-five grams bone ash superphosphate, containing ex- 

 actly 5 grams soluble phosphoric acid, was mixed with 60 grams 

 air dry clay soil, containing 5.11 per cent, carbonate of lime, and 

 6cc. water. After 24 hours in a closed vessel it lost 2.725 

 grams phosphoric acid: 100 parts of soil absorbed, therefore, 

 under these conditions, 4.81 grams phosphoric acid. In like 

 manner other results were obtained, which I have recorded in 

 Table II. 



*Lehrbuch der Duungerfabrikation, p. 69. 



