144 PHILOSOPHICAL TRANSACTIONS. [aNNO I674. 



restrial and acid part, and labours to show, how the spirit of nitre is produced in 

 the earth. For the better understanding whereof, he premises something con- 

 cerning the spirit of sulphur and other acid liquors ; teaching, that that spirit 

 does not exist in sulphur before deflagration or the operation of the fire; and 

 affirming, that, as the nitro-aerial spirit of the fire, by a very brisk motion and 

 effervescence, contending with and acting upon the salino-sulphureous particles, 

 does in a very short time comminute and render fluid the saline parts included 

 in the sulphureous; so the same spirit, boiling up by a more remiss motion 

 with the same salino-sulphureous parts, does in a longer time turn the saline 

 parts into an acid liquor. Where he takes occasion to discourse, how liquors in 

 general become acid by the operation of the nitro-aerial spirit; as also, wherein 

 fermentation consists, viz. in the effervescence of the nitro-aerial particles 

 with the salino-sulphureous ones of the liquor. 



According to this author, sal-nitre is made up of a threefold salt; whereof 

 one, the most active, deduces its origin from the air, and is of an ethereal and 

 igneous nature; and this by its architectonical power forms to itself out of a 

 terrestrial matter a saline vehicle, which, together with the igneous salt residing 

 in it, constitutes the spirit of nitre ; which as soon as it is generated, falls to 

 working upon the fixed salts of the earth brought to due maturity, and together 

 with them makes up the common nitre. From this nitro-aerial spirit he derives 

 all fermentations tending both to the production and dissolution of things. 

 From the same he deduces rigidity, and particularly congelation, and the ex- 

 pansion made therein; where he examines the explication given by Descartes 

 of the rarefaction of congealed water. And as he makes rigidity the eff^ect of 

 that spirit, so he would have the restitution of rigid and infected bodies^ in which 

 consists springiness, to result from the same. And acknowledging, from the 

 many Boylean experiments, * that the air is endowed with a considerable spring, 

 he attempts to give an account, whence that elastic power arises ; taking it for 

 granted, that the air contains store of those nitro-aerial particles, that to him are 

 absolutely necessary to make fire, of which the air being exhausted by deflagra- 

 tion, the fire must needs be extinguished; and assuming thereupon, that the 

 elasticity of the air proceeds from such aerial particles as maintain flame; having 

 found .by experiments, that air deprived of those nitro-aerial parts loses its 

 «pringy virtue; which virtue he also affirms to be lessened by the respiration of 

 animals, who, in his opinion, do exhaust out of the air certain vital, and those 



* To be met with in Mr. Boyle's physico-mecbanical experiraents of the year 1660, at Oxford, 

 and the continuation of the year 1669, at Oxford, where the reader may find a full information of what 

 our author here declares. — Note by Mr. Oldenburg. 



