186 The English School [lect. 



necessary for respiration, and which was used for respiration, 

 but a particular part only of the air ; and, as we shall see, by 

 this particular part, though he called it by a different name, 

 he meant what we now call oxygen. 



The formation of nitre in heaps of decomposing animal and 

 vegetable matter, and the properties of. nitre or saltpetre, 

 especially as the constituent of gunpowder, had foT a long time 

 excited the interests of chemists. Nitre was made the pivot of 

 various chemical theories and ideas. " Nitre, which has made 

 "as much noise in philosophy as in war." 



Sylvius in treating of respiration, of the mechanics of which 

 he gives a fair description, and concerning which he had reached 

 the conclusion that in breathing air passes from the lungs into 

 the blood and produces a notable change in it, has the following 

 remark. " By what power however, or in what manner or way 

 " the inspired air so alters the blood, is not equally clear. I 

 " think it is brought about by reason of there being dispersed 

 "in the air nitrous and sub-acid parts able to condense the 

 " effervescing and rarefied blood and to gently restrain its 

 " ebullition. I distinguish however between the sub-acid and 

 " the nitrous parts of the air, since the sub-acid parts are for 

 "the most part simple, but the nitrous on the contrary are 

 " compound, composed of acids if you like, though not with 

 " any you please, but also of oily parts and lixivious salts, as 

 " is clearly proved by the artificial (i.e. chemical) synthesis and 

 "analysis of nitre." 



Whether Svlvius wrote the above as the result of his own 

 researches or whether he had heard of Mayow's inquiries is not 

 certain ; but in any case Sylvius's obscure views are very 

 different from what we shall see to be the definite and clear 

 conceptions of Mayow. 



In the introduction to his tract on sal-nitrum Mayow 

 undertakes to prove, 



" That this air which surrounds us, and which, since by its 

 " tenuity it escapes the sharpness of our eyes, seems to those 

 " who think about it to be an empty space, is impregnated with 

 "a certain universal salt, of a nitro-saline nature, that is to say 

 " with a vital, fiery and in the highest degree fermentative spirit." 



