92 



sewage, which results in dmining the phosphates, and other substances.- 

 valuable from an agricultural point ot view, into the sea, wheie they 

 may be considered as absolutely lost. Victor Hugo, in a well known 

 passage, contrasts the wealth to be seen i-olling through the streets of 

 Paris to that which is silently but steadily flowing away by the sewers 

 beneath, which he maintains is greater. Be this as it may, in this 

 particular case there is a continuous process on a large scale in action, 

 by which the land is deprived of its phosphates, and particularly in a 

 country like this, which exports great quantities of food material, with 

 their contained phosphates, to be consumed abroad. 



Some years ago (1869) Mr. Gordon Brown calculated the amount 

 of phosphorus actually contained in the grains annually shii)ped 

 from the port of Montreal, estimating it for this purpose in the 

 form of phosphoric acid. Wheat contains about ^^^ (eight tenths) 

 per cent, of phosphoric acid, or about 16 pounds to each ton, and 

 as the total shipments of wheat amounted to 292,534 tons, the 

 quantity of phosphoric acid sent away in it equalled 2,340 tons. 

 Taking the average quantity of this substance contained in good soils,, 

 he found that this meant the total exhaustion to a depth of 12 inches — 

 in so far as phosphates are concei-ned — of 70,320 acres, and would 

 require the use of 5,850 tons of apatite of good quality as manure to 

 maintain the fertility of the fields. Adding to this the amount of 

 phosphoric acid contained in other grains exported he found the total 

 loss in the year to be 2,574 tons of phosphoric acid, representing a 

 value of over $500,000. 



With such statistics in evidence it will not be necessary to enlarge 

 further on the necessity of discovering a source of supjily of phosphates 

 for our fields, and for this we must have recourse to some special!}'' 

 concentrated natural deposits. What therefore is the nature of these, 

 how have they been formed, and where do they occur? 



In answering these questions, it must be remembered that soils 

 have been produced by the decay and disintegration of rocks, and have 

 derived their contained phosphates from the rocky crust of the earth. 

 Good soils contain say about -^^ (two-tenths) per cent, of phosphoric acid, 

 and on analysing rocks chemically or microscopically we find phosphates — 

 generally calcic phosphate — present in thenx in similar small proportions. 



