40G 
Recent Agrmdhtral Publications. 
10. Phosphates, — Mineral phosphates — apatites, phosphorites, 
phosphatic nodules, coprolites, basic cinder. Animal phosphates : 
bones, pliosphatic guanos. Superphosphates. Respective classes of 
soils upon which phosphatic manures are likely and not likely to 
prove useful. 
11. Potash Mamircs, d'c. — Sources of potash manures. Use of 
potash for tubers, root crops, cereals, grass lands, tobacco, and vines. 
Salt. Sulphate of iron. 
12. Chemical 2[anures. — Exclusive use of chemical fertilisers. 
Simultaneous use of chemical fertilisers and farmyard manure, and 
of cliemical fertilisers and green manures. Quantities of chemical 
fertilisers necessary to supplement applications of farmyard or green 
manures. 
13. Analyses of Manures. — Methods of determining the percent- 
ages of potash, nitrogen, and phosphoric acid in the various manures 
that severally contain them. 
14. PHces and Values of 2[anures. — Methods for calculating the 
values of manures, and of their ingredients. Fractions of the value 
of a manure which should be assigned to successive crops grown after 
its application. 
From the foregoing condensed summary it will be apparent that 
M. Deherain’s volume, though dealing with what is strictly speaking 
only one branch of agricultural chemistry, is nevertheless full and 
exhaustive so far as it goes. The work is, moreover, well printed 
and excellently arranged. 
In the third part of the treatise appear some instructive remarks 
upon the disadvantages attending the exclusive use of chemical 
fertilisers, particularly the unfavourable effect these manures have 
upon the physical properties of the soil. An analogy is sought in 
the profound changes which gelatinous substances may be caused to 
undergo in the laboratory. As a case in point, gelatinous silica is 
soluble in acids, but when dried is quite insoluble. Clay, the par- 
tides of which remain in suspension in pure water, becomes coagu- 
lated under the influence of salts, and separates from the liquid 
through which previously it had been diffused. 
In certain classes of soils chemical manures cause clay to behave 
in a similar way ; such soils then become hard, and can be worked 
only with difficulty. This, however, is not invariably the case, for the 
soils at Rothamsted appear not to be susceptible of this influence, 
whereas, in the Isere district of France, M. Michel Ferret has been 
compelled to abandon the exclusive use of chemical fertilisers. 
Again, M. Maercker, in discussing the comparative values of farm- 
yard manure and chemical fertilisers, cites a case at Benkendorf in 
which the exclusive application of chemical manures had brought 
the soil into such a condition that it became exceedingly difficult to 
work. It was, however, found possible to bring this soil back into 
a workable state by the application of lime at the rate of three tons 
per acre, a costly operation, and one that diminished materially the 
