274 The Phosphates used in Agriculture. 



than that of any other country ; consequently, the soil here is 

 caused to do its utmost, and the effects of exhaustion have 

 been sooner and more keenly felt. Although scientific agri- 

 culture, as regards its diffusion among the people, is still in a 

 deplorable state on the continent of Europe, as may be seen 

 by glancing from time to time at the periodical literature of 

 Belgium, France, Germany, and Italy, the time will certainly 

 come when the art of manufacturing and applying manures of 

 all descriptions will be as actively pursued in these countries 

 as in England at the present day. 



Three of the more important ingredients which soils lose 

 by cultivation, and which it is necessary to restore to them in 

 greater or smaller quantities, are potash, nitrogen, and phos- 

 phate of lime. Nature herself supplies these substances to 

 the soil in various ways, and in quantity sufficient for the 

 growth of wild plants. Thus, potash is washed into the soil 

 by the rain-waters which flow over granitic and felspar 

 rocks, so that every little stream contains some of it ; nitrogen, 

 in the form of ammonia, is constantly present in the atmosphere, 

 and phosphate of lime is very widely distributed over the 

 globe. Moreover, the excrements of animals contain all three. 

 Another ingredient very essential to vegetable life is carbonic 

 acid, of which there is so large a supply in the atmosphere, in 

 the streams, and rocks of the globe, that it is rarely necessary 

 to supply it artificially io our cultivated crops. 



I have said that nature supplies a sufficiency of these more 

 important constituents of the fertile soil, to ensure the growth 

 and luxuriance of wild plants. But in agriculture we are 

 dealing with an artificial state of things, and the natural supply 

 no longer suffices to maintain fertility in our cultivated soils. 

 In our present system of manuring potash is supplied by 

 farm-yard manure, sometimes by wood-ashes, and by manures 

 made by drying the excrements of animals (sewage, etc.) 

 The first and last of these supply also ammonia and phosphates. 

 Oar chief sources of nitrogen are Peruvian guano, nitrate 

 of soda, and sulphate of ammonia (from the gas-works). The 

 first, of these supplies, at the same time, phosphate of lime, and 

 the last is sometimes introduced into artificial manures, 

 such as the ammoniaca] superphosphates. 



Oar sources of phosphate of lime are most numerous, and 

 it is to these alone that I shall devote the present paper. A 

 few years ago, all the phosphorus used for tho manufacture of 

 Lucifer matches was extracted from bones, tho phosphate of 

 lime used is the various manufactories was likewise obtained 

 from bones. These were principally collected in tho streets and 

 waste places, at butchers' establishments, etc. Since the 

 manufacture of BV/perphosphate of lime began for the use of the 



