I 



On Sal Nitrum and Nitro- Aerial Spirit 3 



constituent elements. For if the acid spirit of nitre is 

 poured upon any alkali, or, in place of the alkali, upon 

 purely saline volatile salt, from the mutual strife of 

 these two things coming together and the intense 

 action, sal nitrum is generated, which will readily 

 deflagrate when thrown into the fire. So that nitre 

 would seem to be born fit for fights and hostile 

 encounters, since it derives its origin from the mutual 

 conflict of opposing elements and from enmity 

 itself. 



The constituents of nitre having been in this way 

 considered, let us next inquire how sal nitrum is 

 produced in the earth. For from almost any soil 

 impregnated by the air and the weather, but especially 

 from such as abounds in sulphur and fixed or volatile 

 salt, as that from stables, dovecots, and slaughter- 

 houses, sal nitrum is abundantly derived, and from 

 its source is well called sal terrce. 



As to the mode in which nitre originates in the 

 earth, the generally received opinion is that the earth 

 as its proper matrix draws sal nitrum from the air in 

 virtue of its own attractive force. And, indeed, there 

 can be no doubt whatever that the air contributes in 

 no small degree to the generation of nitre, since nitre is 

 only evolved from soil which is impregnated with air. 

 Moreover, if earth from which all the nitre has been 

 lixiviated be exposed to the air, it will after some lapse 

 of time abound once more in nitre. 



But, assuredly, one can scarcely suppose that the 

 nitre itself is all derived from the air, but merely its 

 more volatile and subtle part, the rest of the nitre 

 being due to the earth, for of the nitre obtained from 

 the earth, by no means the least part is a fixed salt 

 which is not volatilised by the very fiercest fire. For 

 in the distillation of nitre, only the acid spirit of 



