CHEMISTRY. 715 



method proposed is as follows: Shake 300 gm. of the soil for 6 hours 

 with 1,300 cm. of water in a lh liter flask, placed horizontally in a 

 rotary machine making 2 revolutions per minute. Filter off 1 liter of 

 the solution for the determination of phosphoric acid. The nature 

 of the water used (even the presence of considerable amounts of 

 carbon dioxid or bicarbonates) apparently has no great effect upon 

 the result. 



The amount of soluble phosphoric acid found by this method in dif- 

 ferent soils was very small, rarely exceeding 0.001 gm. per liter of 

 extract, or 0.45 kg. per hectare. It appears that the amount of soluble 

 phosphoric acid which water will remove from soil is the result of an 

 equilibrium of two opposing classes of chemical action ; one class tend- 

 ing to render the phosphoric acid insoluble, the other to make it soluble. 

 This tendency toward equilibrium is believed to cause a constant renewal 

 of soluble phosphoric acid in the soil as fast as it is used by the plants. 

 Thus while the amount of phosphoric acid in this form in the soil at any 

 given time is found to be exceedingly small, it is by no means unimpor- 

 tant as a factor of plant food supply. 



Determining the density of sugar cane, A. A. Ramsay ( Queens- 

 land Agr. Jour., 3 (1898), JVb. 5, jap. 359-361). — The author recommends 

 that a few canes, from 3 to 8, which apparently represent the average 

 crop be selected and split into quarters longitudinally, one quarter being 

 used for the extraction of the juice. The density of the thoroughly 

 mixed juice from the different canes is determined by means of a saccha- 

 rimeter or Brix spindle, the temperature of the juice being kept at 

 about 20° C. In estimating the total soluble solids in the cane from 

 the density thus determined it is assumed that the cane contains 10 per 

 cent of fiber saturated with 90 per cent of juice. The equation thus 

 becomes 



90 

 Soluble solids in cane = Density of juice x -^- 



The proteids of cream, E. F. Ladd (Jour. Amer. Chem. Soe.,20 

 (1898), No. 11, 858-860). — In determining the casein, albumen, albu- 

 moses, and peptones in cream, the author dilutes 10 gm. of cream with 

 80 cc. of water and precipitates the casein with 3 cc. of saturated alum 

 solution, the albumen in the filtrate by heating, the albumoses by satu- 

 rating the filtrate with zinc sulphate, and the peptones by partially 

 evaporating the filtrate and adding 80 per cent of the volume of absolute 

 alcohol. Analyses are given of 1 sample each of fresh and ripened 

 cream, the latter quite sour and ready for churning. These indicate 

 that "the loss in working by these methods was not great, and further 

 that there is not a very marked change in the proteids of cream during 

 the process of ripening." 



The fundamental principles of agricultural chemistry, R. Otto {(irundziige der 

 Agrikulturchemie. Berlin: Paul Parey, 1S9S, pt. 1, pp. 160, fiys. 14). — The work is 

 intended for agricultural, forestry, and horticultural schools, as well as for self- 

 instruction. This part is devoted to a discussion of the suhjects of air and soil. 



