071 Sal Nitriim and Nztro-Aerial Spirit 5 



part consists, is derived from the earth — and for this 

 reason, that it cannot, as we have already indicated, 

 reside in the very rare air on account of its highly 

 fixed nature. It favours this view that from earth 

 impregnated with fixed or volatile salt, as from stables 

 and also from soil containing quicklime or ashes, sal 

 nitrum is lixiviated in greater abundance than from 

 any other soil, because these salts, united in course of 

 time with nitro-aerial spirit in a way to be explained 

 below, are converted into nitre. And, indeed, it is 

 probable that ashes, quicklime, and the like, fertilise 

 the soil, for this reason only, that they afford fixed 

 salt for the production of nitre, as will be shown 

 below. 



Here, perhaps, some one will object that if earth 

 from which all the salts have been lixiviated is ex- 

 posed to the air, sal nitrum will, after some time, be 

 produced in it anew. 



I reply that seeds of fixed salts exist, although 

 obscurely, in all soil, even in that which has been 

 lixiviated, and that these, by the force of a sort of 

 aerial ferment, are digested in course of time into 

 fixed salt, as I shall endeavour to show below. That 

 the earth is impregnated with a certain universal seed, 

 fecundating all things, has long been a received 

 opinion. Why, then, not suppose that this macro- 

 cosmic seed is either itself fixed salt or, at least, the 

 seeds of fixed salts hidden in the bosom of the earth ; 

 and that these when brought in progress of time to 

 maturity are, together with nitro-aerial spirit, changed 

 into sal nitriun. And it is a proof of this that nitre 

 generated in the bowels of the earth contributes in no 

 small degree to the growth of plants, as will be shown 

 below. For as metallic seeds here and there dispersed 

 through the mass of the earth are in the course of 



