4 



i 



192 



MANURES. 



Sect. X. 2. 2, 



J' 



Oxygen gas coiififts of oxygen and heat j and when it unites witr 

 fuch bodies, as are capable of uniting with it, the heat is fet at liberty 



fpiration and in combufi: 



both which procelTes 



d 



is produced by the combination of oxygen with fome inflammabl 



bafe 



Hence vital air confifts of oxygen diflblved in the fluid 



of heat ; bat there is alfo another fluid, which feems to be combined 

 with this folution of oxygen in heat, and that is light. For when 

 oxygen becomes combined with charcoal, or with fulphur, or with 

 phofphorus, both heat or light are fet at liberty from thefe new com- 

 binations of oxygen ; which thus produce the carbonic, fulphuric, 



d phofphoric acid 



Wh 



thefe 



ew combinat 



of 



oxy 



are performed very 



flowly, the light is fometimes not vifible, as in the heating of a dung 

 hill ; in which procefs the oxygen in the cells or cavities of the hot 



bed 



flowly with the carbon and phofphorus of the decompof- 



^ vegetable and 



mal matters ; but though much heat is 



given 



D 



ht is feeii. While on the contrary from rotten wood 



putrefcent fifh, when expofed to the atmofphere, much light 



emitted, but not much fenfibl 



heat, owing perhaps 



fimply to th 



combuflion of the phofphorus, which they contain. 



2. The products of thefe combinations of oxygen with other bodies 

 may all of them be termed acids ; though in fome the heat or light 



liberty converts thefe acid prod unions 



fet at 



and charcoal form carbonic acid 



^-H* 



new 



produdl 



^.^ 



d 



oth 



fles 

 It 



oxy 



fleam, which is condenfible by cold 



th 

 ful 



phuric acid from the comb 



of oxygen and fulphur ; and the 



phofphoric acid from oxygen and phofphorus. 



3. Other combinations of oxygen with heavier fubftances are pro 



duced 



th 



atmofphere with 



th 



fcp 



heat, or vifible light ; as the union of oxy 



of either fenfibli 

 th metallic bodies 



with that of mangaiiefe, with zinc, lead, iron, as in common 



of manganefe 



> 



lapis calaminaris, white calciform lead-ore, and th 



8 



red 



I 



H 



