Two methods of determining the weight and one method of determining the volume of water imbibed by a soil have been discussed. The results of these methods have been shown to be concordant by an independent method.

The tentative conclusion reached is that the weight of water a soil imbibes can be readily determined by Fisher's method or from the Keen-Raczkowski box, but that the volume of imbibed water cannot yet be directly determined accurately.

1. Humic acids and ammonium humates prepared by a patented process of gentle oxidation of coal were examined as fertilisers by laboratory nitrification experiments and pot-culture tests on four soils and by a number of field experiments on a range of soils and crops during a single season.

2. In all tests the effects of ammonium humate could not be distinguished from those of ammonium sulphate of equal ammonium content. The nitrification tests and the pot cultures afforded some evidence of a slow production of nitrate or available nitrogen from the humic acid.

3. In the field experiments as in the pots there was no clear evidence of any fertiliser value apart from that due to the ammonium present.

The following paper is the first of a projected series on the results of work which has been in progress in the Animal Calorimetry Department of this Institute during the past five years. Subsequent papers will deal with body temperature variations, effects of environmental temperature, metabolism, energy expenditure, etc.

The note by E. J. Sheehy on a method of correction in the weight curve of certain animals in group-feeding experiments(l) has been brought to the author's notice.