38 Mayow 



this way that at the time when vegetables chiefly 

 spring from the earth, the nitro-aerial spirit ferments 

 most actively with terrestrial matter, and sal nitrunt 

 is chiefly produced in the earth : in fact experience 

 shows that nitre (which we suppose to be formed by 

 nitro-aerial spirit effervescing with the saline-sulphu- 

 reous particles of the earth) is produced in the earth 

 in greater abundance in the beginning of spring than 

 in the other seasons of the year. In winter, indeed, 

 nitro-aerial particles and terrestrial sulphur are com- 

 pressed by frost and are fettered as it were and 

 hindered almost from moving at all. But at the be- 

 ginning of spring nitro-aerial spirit is set in motion by 

 the greater heat of the sun, and the structure of the 

 earth is laid open now that the ice has melted. And 

 then the nitro-aerial spirit set in motion descends deep 

 into the earth, and meeting there with its saline-sul- 

 phureous particles, minutely broken, gives rise to an 

 intense enough effervescence, with the result that 

 nitre is generated in abundance, and plants grow up 

 luxuriantly. 



From what has been said we can see why animal 

 excreta, salts of lye and also quicklime, and similar 

 substances imbued with fixed salts fertihse the soil. 

 Indeed the saline-sulphureous excreta of animals, as 

 also fixed salts in union with terrestrial sulphur, are 

 specially adapted for effervescing with nitro-aerial 

 spirit, and they also supply appropriate material for 

 the production of nitre and consequently contribute 

 not a little to the production of plants. 



Thus then the so much talked of fermentation by 

 which the numerous family of plants is produced from 

 the bosom of the earth, appears to be nothing else 

 but the internal motion of nitro-aerial particles when 

 they meet with the sulphur and salt of the earth, in 



