8 On the various Cotnhinatlons of Carbon with Oxlgeti. 



to convert them into pure carbonic acid, from their being procured bjr a mixture of me- 

 tallic calces and charcoal in the drieft poflible ftate, in which procefs the metallic calx is 

 found to be revived, having parted with its oxygen to form the gafeous oxide and acid ; and 

 from their being obtained by the partial decompofition of this fame acid, as in the expe- 

 riments with chalk and iron filings, &c. From this laft circumftance it would alfo appear, 

 that carbonic acid when raifed to a high temperature may be decompofed by any fixed 

 fubftance which has a confiderable affinity for oxygen. Upon the whole, therefore, we 

 confider the gafeous oxide of carbone as holding the fame relation to pure hydrocarbonate 

 and carbonic acid j which nitrous gas, or the gafeous oxide of azote, does to pure azote 

 and nitrous acid. We llkewife conceive, that the objeftions to the new fyftem of che- 

 miftry advanced on this head, by Dr. Prieftley, are fufficiently anfwered. We find that 

 thefe gafeous oxides are very different from what the Dodtor conceived them to be, and 

 that the prefence of water does not appear to be neceffary to their produftion. We have 

 no more reafon therefore to fuppofe that the grey oxide of iron fhould contain water, than 

 that the other oxides, which give the very fame produfts when mixed with charcoal and 

 didilled, fhould contain it likewife. 



^ Table Jhetv'tng the Analyfis, tjfc. of the different Species of Hydrocarbonates, and the gafeeus 



Oxide of Carbone. 



In the preceding table, the weight of one loO cubic inches of common air, under the 

 mean preffure of the atmofphere, and at the temperature of 55° feet, is eftimated at 31 

 grains ; the quantity of pure carbone in carbonic acid at ^ of the whole nearly, and the 

 proportion of oxygen to hydrogen in water as 85 to 15. 



The quantity of oxygen in the gafeous oxides was thus eftimated. In the laft line, for 

 example, we find that 30 grains of the oxide, produced, when combined with 13.6 grains 



of 



