ON THE NEW SYSTEM OF CHEMISTRY. l$% 



air from the chalk) was decompofed by the iron ; whereas 



when he ufed well burned lime he got little or no air. What which the Dr. 



.... . . does not infer to 



1 infer from this experiment is, that the chalk, not being per- be car t, on ic acid 



fec"rly calcined, contained fome water, as well as fixed air, decompofed; but 



and that this water uniting with the phlogifton of the iron ^fonTrMnthe"' 



formed the inflammable air that he found. Water I fuppofe iron. 



to be the bafis of all the kinds of air, and many fubftanees 



retain it in any degree of heat. Chalk I have found to do it 



after long expofure to the heat of a fmith's forge. 



Admitting the fixed air procured in the ^experiment with If the carbonic 



the finery cinder and charcoal to come in part from the *^ d d ' e J3char^ 



oxigen in the finery cinder, how is this oxigen to be expelled coal, derive its 



from the calx, fince heat will not do it ? And there is no in- ox jf n ( r ? m *■ 



n m '• i. . i -n • i-i i 1 i oxide, this prin- 



ltance, I believe, in chemiftry, m which when heat alone c i p ] e muft, it is 



will not expel any conftituent part of a fubftance, it can be ^ted, be tranf- 

 effecled without the aid of an affinity, in confequence of which t0 t j )e i aws f 

 fome other fubftance takes its place. But here, according to afhnity. 

 the new theory, nothing is fuppofed to take the place of the 

 oxigen in the finery cinder. It takes nothing from the char- 

 coal, but the iron is revived by the mere expuliion of the 

 oxigen. 



Mr. Cruikfhank Jays great ftrefs on the difference that he The difference 

 found in the air that he procured in thefe procefles from that betw " n *» e al 



. , t-»ti r 3n " tnat " 0m 



which is got from charcoal and water. But I have obferved, merewaterand 

 that there is a confiderable difference in the qualities of heavy charcoal, ftated 

 inflammable air, not only according to the fubftance from clufiveargu- 

 which it is procured, but in the fuccefTive ftages of the fame menu 

 procefs. He will find that I have examined this kind of air 

 as procured from a great variety of fubftanees, made to pafs 

 in the form of vapour through hot earthen tubes, and in va- 

 rious other ways, and have given the analyfis of them. I 

 •always found that the firft portions from charcoal were loaded 

 with fixed air, but that in the courfe of the procefs this dis- 

 appeared, the air burning with a lambent flame, and that to- 

 wards the end it approached to the explofive kinds, as ob- 

 tained from metals by acids. 



I alfo found that more or lefs fixed air is procured by the Oxigen com- 

 decompofition of heavy inflammable air by means of dephlo- bmed with heavy 



.„.'.. ,,,, • , r r -i inflammable air 



gifticated air ; and though the air procured from finery cinder affords carbonic 

 and charcoal fhewed no fign of its containing any mixture of acid > j n g reate r 

 fixed air, nothing of the kind being difcoverable by lime ?he"atter • which 



water ; 



