relative to Black, Watt, and Cavendish. 503 



voisier, and the inferences of those earlier philosophers whose 

 speculations we are engaged in investigating: but when we follow 

 Mayo w's deductions from the assumption, on probable grounds, 

 that there exists in the atmosphere a gas which in the act of 

 combining with other bodies produces the phaenomena of com- 

 bustion, — when we observe him concluding the identity of his 

 gas with one of the components of nitre from the atmospheric 

 production of that salt, and from the sameness of its effect in 

 enabling substances to burn, — when we further observe him 

 determining it to be fixed in the acid component* of nitre, and 

 supporting this view of the subject by alleging the sameness 

 of the effect of nitric acid and of the burning-glass, in adding 

 to antimony weight and specific medical properties, — when 

 we find him extending these views to other substances, stating 

 with most remarkable accuracy the acidification, in various 

 cases and degrees, of sulphureous and fermenting substances 

 by atmospheric exposure, and hence inferring that this gas is 

 the principle not only of combustion but of acidity f, — when 



* " Jam vero cum pars nitri aerea in spiritu ejus acido existat, non vero 

 in sale fixo, quod reliquam nitri partem constituit, uti supra ostendimus, 

 concludere licet particulas igneo-aereas nitri, quae cum parte ejus aerea idem 

 sunt, in spiritu nitri reconditas esse." — De parte aerea igneaque Spiritus 

 Nitri, p. 18. 



t After stating (Ibid. p. 37) that the acid of oil of vitriol is not due to 

 any acid already existing in sulphur, of which he says there are no signs, 

 he adds — " potius putandum est, particulas ignis nitro-aereas, in longa 

 ilia distillatione vitrioli, cum sulphure metallico Colcotharis congredi et 

 effervescere: uncle fit quod particular sulphuris istius salinae, inter particulas 

 igneas mutuo se atterentes interpositae, contundantur et comminuentur,ita 

 ut eaedem tandem exacuantur, et ad fluoris statum perducantur, quae demum 

 ignis vi in altum delatae, oleum vitrioli componunt, haud multum secus ac 

 spiritum sulphuris (sulphurous acid gas) per deflagrationem ejus fieri supra 

 ostendimus." " Si vitriol urn ad totalem spiritus acidi expulsionem calcina- 

 tum, aeri humido aliquamdiu exposition fuerit, idem spiritu acido de novo 

 impraegnabitur. Nempe spiritus nitro-aereus cum sulphure metallico Co/co- 

 tharis lente congreditur, motuque obscuro cum eodem effervescit; unde 

 fit, quod particulas salinse, aut metallicae sulphuris istius, modo supra dicto, 

 ad fluorem perducantur. Profecto vix concipi queat qua alia ratione spi- 

 ritus iste vitriolicus in Colcothare produceretur; neque enim idem in Col. 

 cothare mox e distillatione extitit; neque putandum est eum totalitcr ab 

 aere prosapiam ducere, ut alibi ostensum est." " Vitriola e lapide seu po- 

 tius glebe salino-sulphurea (vulgo Marchasitam vocant) conficiuntur, e qua 

 igni commfesa flores sulphuris vulgaris, copia satis ampla, eliciuntur: post- 

 quam autem gleba ea aeri,astrisque pluviis, aliquandiu exposita est, et dein, 

 prout ejus fert natura, sponte sua fermentata est, eadem vitriolo ubertim 

 impraegnabitur : nimirum spiritus nitro-aereus cum sulphure metallico viar- 

 chasitarum istarum effervescens, partem earuui fixiorem in liquorem acidum 

 convertit, qui mox ab ortu suo particulas metallicas lapidis adoritur, evo- 

 catque ; tandemque cum iisdem in vitriolum coalescit. Quinetiam Itubigo 

 ferri, quae naturalam vitriolicam obtinet particularum nitro-aerearum cum 

 sulphure ferri metallico congredientium actione produci videtur." " Ani. 



