17 



The reaction is a typical absorption and the quantity of dye 

 taken up depends on the strength of solution used, an equilibrium 

 setting up between dyed soil and dye solution. For comparing 

 surfaces of soils it is therefore necessary to estimate the dye absorbed 

 when the dyed soils are in contact with supernatant dye solutions of 

 the same strength. A series of dye solutions has therefore to be 

 used for each soil and the appropriate concentration picked out 

 by trial. 



XIII. "The Humus of Acid and Alkaline Peats." J. A. 

 Hanley. Journal of Agricultural Science, 1914. 6, 

 63—76. 



Experiments were made to determine whether acidity or alka- 

 linity of peats depends on the presence of acid or alkaline humus. 



In every case part of the organic matter could be extracted 

 without previous treatment with acid, and when the soils were 

 arranged in order of the ratio of humus obtained without, to humus 

 obtained with, previous acid treatment, alkaline fen peats, some of 

 which contained carbonate, were found high in this "acidity" list. 



Five typical peats were examined in more detail. 



The humus determinations were repeated with ammonia and 

 with caustic soda, and the nitrogen in the extracts was estimated, 

 but the results, which were probably affected by the solubility of 

 neutral organic matter, showed less connection with the other 

 characteristics of the peats than those obtained by studying the 

 inversion of sucrose. 



Acid peats have a greater power of inverting sucrose than 

 neutral peats. In order to eliminate the effect of varying organic 

 matter content it was found necessary to compare the ratios of 

 inversion after, to inversion before, treatment of the soil with dilute 

 hydrochloric acid. For acid peats the ratio approached 1 , for normal 

 peats it was very low ; in the case of a Cambridge Fen peat, 0'062. 



XI Y. "The Relative Effect of Lime as Oxide and Carbonate 

 on certain Soils" H. B. HUTCHINSON and K. 



MacLennan. Journal of Agricultural Science, 

 1914. 6, 302—322. 



Further evidence is adduced to show that caustic lime acts 

 as a partial sterilising agent, as pointed out in the previous paper 

 dealt with in last year's Report. The amount of lime required for 

 this purpose is found to vary with different soils. Each soil absorbs 

 a certain amount of lime ; only the excess over and above this 

 absorbed quantity produces any sterilising effect. In addition, the 

 lime liberates a certain amount of ammonia. The available nitrogen 

 in the soil as found by pot experiments was found to be comparable 

 with the amounts of ammonia and nitrate produced in the laboratory 

 experiments. 



Chalk, on the other hand, has no partial sterilising action. 



XV. "The Determination of Soil Carbonates." H. B. 

 Hutchinson and K. MacLennan. Journal of 

 Agricultural Science, 1914. 6, 323—327. 



A method is described for rapidly estimating the carbonates in 

 soil. The apparatus consists of two round bottomed flasks of 100 



