1 86 Analyjis of the Jir. 



From the little quantity of air which is 

 obtained by the diftillation of that very fixt 

 body fea-falt, in Experiment 71. in compa- 

 rifon of what arifes from nitre and Sal Tar- 

 tar, we fee the reafon why it will not go 

 off with an explofive force, likethofe when 

 fired. And at the fame time we may hence 

 obferve, that the air included in nitre and 

 Sal Tartar, bears a confiderable part in their 

 cxplofion. For fea-falt contains an acid 

 fpirit as well as nitre - y and yet that without 

 a greater proportion of air does not qualify 

 k for explofion, thro' mixed like nitre in the 

 eompoiition of gun-powder, with fulphur 



and charcoal. 



Mr. Boyle found, that Aqua-f or tts, poured 



on a ftrong folution of fait of tartar, did not 

 fhoot into fair cryflals of falt-petre, till it 

 had been long expofed to the open air ; 

 whence he fufpedted, that the air contribu- 

 ted to that artificial production of falt-petre. 

 And fays, " Whatever the air hath to do in 

 tc this Experiment, we have known fuch 

 tl changes made in fome faline concretes 

 <c chiefly by the help of the open air, a 

 <c very few w ? ould be apt to imagine.'* Vol, 

 I. p. 302. and Vol. III. p. 80. And Chy- 

 rnifts obferve, that when the effemial falts 



of 



