CHEMICAL SCIENCE. 203 



ammoniaco-magnesian phosphate. 11. The analyses hitherto made 

 of fermented manures have been defective, in that they have not taken 

 into account the loss which results from the action of carbonate of 

 lime on the salts with ammoniacal bases, during the desiccation of the 

 manures. It results, that the tables representing the proportion of 

 nitrogen in manures, which have been published, can only give ap- 

 proximations. 12. The comparative values of manures cannot be 

 decided by merely taking account of the quantity of nitrogen which 

 they furnish by analysis, because, on the one hand, nitrogenous mat- 

 ters are not the only active elements in manure, and because the value 

 of manures very much depends on the form under which the nitrogen 

 exists in them ; and, consequently, it is not possible to establish a 

 table of equivalents for manures. 13. Finally, we must add to all 

 these facts the remarkable observation of Mulder, who has proved 

 that humus condenses the nitrogen of the atmosphere, and transforms 

 it into ammonia. 



ACTION OF SOILS ON THE CONSTITUENTS OF MANURES. 



THE results of some important experiments respecting the action of 

 soils on the constituents of manures have been laid before the Royal 

 Agricultural Society, by Professor Way. Some of these experiments 

 repeated before the society were as follows : Several glass filter 

 jars were prepared, filled with a red soil to the depth of five or six 

 inches. Upon one of these Mr. Way poured water obtained from one 

 of the sewers of London. To another filtering jar he added a quantity 

 of the fetid liquid produced in the steeping of flax. Both of these 

 liquids were turbid, highly colored, and exceedingly offensive to the 

 smell ; but when passed through the soil, they were no longer the 

 same. The resulting liquid had an earthy smell, it is true, a smell 

 always accompanying soils, but was no longer offensive to the nose. 

 Now, to what ingredient of the soil is this metamorphosis due ? Is it 

 due to the sand acting as a filter 1 It was easily proved that such was 

 not the cause ; and that there might be no doubt on this subject, Mr. 

 Way passed through a filtering-jar, containing more than nine inches' 

 depth of fine white sand, a quantity of cow's urine taken from a tank 

 in the country. The liquid was so far altered by the filtration that 

 the turbidity was removed, as it would be by filtration through paper, 

 but the color and disgusting smell remained in all their intensity. 

 Sand, therefore, obviously was not the active ingredient in soils in 

 respect to the power under discussion. The same must be said of the 

 different forms of gravel, which were only coarse sand. The other 

 great ingredient of soil was clay, and to this Mr. Way attributed 

 the power in question. As an experiment comparative with the last, 

 he passed the same tank-water through sand, mixed with one fourth 

 of its weight of white clay in powder. The liquid coming through 

 was clear and free from smell ; indeed it was hardly to be distin- 

 guished by its external characteristics from ordinary water. There 

 can be no doubt, then, that the property of soils to remove coloring 

 matters, and organic matters yielding smell from solution, is due to 



