'evaporation of the water of these lakes, such as would take place in 

 arid regions., imm -n&e deposits of marine vegetation and common salt 

 would oc eiir, In the oxidation and nitrification of this organic matter 

 due to fermentative action, the organic nitrogen would be changed into 

 the inorganic state. In the presence of calcareous rocks, the nitrate of 

 calcium would be formed, which, finally, by double decompositions, 

 would result in the formation of nitrate of soda, the form in which 

 these deposits now exist. The fact that iodine is found in greater or 

 less quantity in these deposits of soda saltpetre, is a strong argument 

 in favour of the hypothesis that they are due to marine origin. Iodine 

 is found only in sea and never in terrestrial plants. Further than this, 

 attention should be called to the fact that these deposits of nitrate of 

 soda contain neither shells nor fossils, nor do they contain any phos- 

 phate of lime. It is hardly credible, therefore, that they are" due to 

 animal origin. The activity of ferments in these great deposits of 

 marine plants, although taking place perhaps millions of years ago, 

 has served to secure for the farmers of the present day vast deposits of 

 nitrate of soda, which prove of the utmost value in increasing the yield 

 of the field. To every quarter of the globe where scientific agriculture 

 is now practised these deposits are sent. They are of such vast extent 

 that it is not likely they will soon be exhausted, and the labours of the 

 agriculturist for many hundreds of years to come will continue to be 

 blessed by reason of the activity of the insignificant microscopic fer- 

 ments which plied their vocation in past geological epochs. 



Because at the present time there are known deposits of marine vege- 

 tation undergoing nitrification, is no just reason for doubting the ac- 

 curacy of the above mentioned hypothesis. Our geologists are not ac- 

 quainted at present with any locality in which deposits of phosphate are 

 taking place, but the absence of the process can not be used as a just 

 argument against any of the theories whicn have been pioposed to ac- 

 count for the immense deposits of this material which are found in 

 various parts of this and other countries. Another illustration of this 

 point may be found in the coal deposits. The environment which de- 

 termines the geologic conditions now is not favorable to the develop- 

 ment of large quantities of organic matter from which coal might be 

 produced by changes in the level of the earth's surface In fact, all 

 the teachings of palaeontology show beyond a doubt that life in the past 

 geological ages was on a far larger scale than at present. In those re- 

 mote times the mean temperature of the earth's surface was very much 

 greater than it is at the present time There are many indubitable 

 evidences of the fact that high equatorial temperatures prevailed even 

 at the poles, while the present tropic and temperate zones were pro- 

 bably too warm for any forms of life which now exist. The fossil re- 

 mains of animals and plants of those ages show the gigantic scale on 

 which all animal and vegetable life was formed. When crocodiles 

 were nearly 70 ft. in length and dragon flies 3 ft. long, it is not sur- 

 prising that both terrestrial and marine vegetation existed in a far 

 more exuberant form than at present. The dense teri'estrial vegetation 

 which made the coal deposits possible were doubtless equaled by ma- 

 rine vegetable growth capable, by oxidation under favorable circum- 

 stances, of forming the vast deposits of nitrates which have been dis- 

 covered in various parts of the world. The depression of the surface 



