THE FARMER'S MAGAZINE. 



473 



Ready-formed ammonia . . 



* Organic matters 



** Inorganic matter (ash) . 



Before After 

 filtration filtration 



through soil. 



7.67 7.13 

 358.40 301.70 

 312.90 245.70 



Total of solid matter . . 678.97 554.53 



* Containing nitrogen .... 15.54 12.60 

 Equal to ammonia 18,86 15.30 



Silica 4.75 15.08 



Phosphates of lime and iron 36.32 33.14 



Carbonate of lime .... 29.79 21.22 



Sulphate of lime 7.14 trace 



Carbonate of magnesia .... 4.98 2.36 



„ potash 148.69 85.93 



Chloride of potassium 30.32 39.49 



„ sodium 50.91 48.48 



** Total of ash 312.90 245.7.0 



" The amount of ready-formed ammonia retained 

 by this soil, it will be seen, is very trifling indeed ; 

 nor is the proportion of nitrogen which is retained 

 in the soil in the form of nitrogenized organic 

 matters very great. We are thus presented with 

 an instance, showing clearly that there are soils 

 which do not possess the power of absorbing 

 ammonia in any marked degree. In the case of 

 such soils as the one used in this experiment, I 

 think it would be hazardous to apply manure in 

 autumn. I may also mention a curious circum- 

 stance in connection with this soil. I am informed 

 that guano and ammoniacal manures do not here 

 seem to do much good, whilst the application of 

 nitre is followed with marked effect." 



The reader, when he is studying the varying yet 

 always considerable power of cultivatable soils to 

 absorb the impurities of decomposing substances, 

 will not fail to remember that the trials of Voelcker, 

 of Thompson, and Way where made with impure 

 liquids on soils free from plants. If, then, we are 

 calculating the deodorizing or purifying powers of 

 a given extent of soils, such as those which these 

 chemists examined, we must make a large addition 

 when we regard the same extent of land densely 

 tenanted with the grasses. That plants possess 

 very considerable powers in this way, was long 

 since shown by the experiments of Saussure and 

 others with, plants placed in various solutions of 

 saline and organic matters. 



By such modes of purifying our rivers, by inter- 

 cepting our sewage, let us not forget, too, that we 

 are taking another leaf from Nature's book, and 

 that her teachings are founded on God's laws. I 

 have often had occasion to allude to that truth, and 

 I am glad to find that Dr. Cameron, in his 

 '' Chemistry of Agriculture," is with us on the 

 question. He observes {Irish Farmers' Gazette, vol. 

 xvi., p. 957) : — 



" I do not mean to assert that the identical lots 

 of guano which are daily landed on our quays did 

 actually pass down our river in another form ; but 

 I do say what is of equal practical importance, that 

 the raw materials from which guano is prepared 

 by the natural producers of that article are to be 

 found every day in the rivers of all the cities in the 

 world, and in such quantities as must appear in- 

 credible to those unaccustomed to reason on such 

 matters. These materials, the contents of our 

 sewers, are carried into the sea, and there furnish 

 food for vast fields of marine plants. These plants, 

 in their turn, go to support the teeming animal life 

 of the ocean — the multiform denizens of the deep. 

 Of these, generation succeeds generation, and 

 myriads of them, in ceasing to dwell in the ' water 

 under the earth,' become the food of birds which 

 move in the ' Heavens above.' The excreta which 

 these deposit in their resting places, and the bodies 

 which they ultimately lay down in death, form 

 accumulations similar to those enormous guano 

 banks which of late have become of such com- 

 mercial importance throughout the entire civilized 

 world, given so great an impetus to agricultural 

 improvement, and so largely contributed to supply 

 the demand for food of an increasing population. 



"This seems going at a great distance for proof 

 and illustration of the value of what lies, or rather 

 runs, under our feet. The journey will not, how- 

 ever, be considered by any means too great, if the 

 knowledge acquired is found in the end to have 

 contributed in any measure to the realization of 

 the practical truth involved in it. An important 

 object is gained if it teach the citizen and farmer 

 the advantage which both would derive from the 

 direct application to our soil of those streams — 

 rich in the food of plants, but fraught with poison 

 to animals — which flow from the filthy veins of our 

 cities, and are lost in the ocean." 



THE POTATO DISEASE.— ITS EXTENT AND ORIGIN. 



The return of the epidemic disease, which for the last 

 twelve years has, with short intervals, cominilted such 

 ravages on the potatoes, gives reason to fear that its con- 

 tinuance may be calculated on, or at least that the 



growers can never be sure of immunity from its ravage?. 

 We have been making inquiry among the London potato 

 merchants respecting the extent to which the tubers 

 are affected, and we are sorry to find them in perfect 



