S48 Dr, Thoinsoti*s Answer to the Review of the [April, 



resemblance to oxygen than to sulphur. At any rate Mr. 

 Brande has no right to find fault with this part of my arrange- 

 ment since he has followed it himself. 



The only simple incombustible known is azote. The Reviewer 

 is very facetious at my stupidity in believing azote to be incom- 

 bustible. And I shall willingly come over to his opinion as soon 

 «s he shows me that he can set it on tire. 



What pitiful quibbling is he guilty of in order to make out the 

 combustibility of this substance ! Were it really combustible, no 

 fire could be kindled without exploding and destroying the whole 

 air of the atmosphere. The very circumstance that atmospheric 

 air has continued unaltered, notwithstanding the infinite number 

 of fires which have been burning for these six thousand years, I 

 hold to be a decisive proof that azote is incombustible. I have 

 given an explanation of what I mean by combmtiouy in my Sys 

 tern, and the meaning which I affix to it coincides with the usual 

 acceptation of the v/ord. If the Reviewer chooses to take the 

 word in a different sense, what have I to do with that ? He 

 might with just as much propriety substitute the word heavy for 

 lifrht, and then affirm that hydrogen gas is the heaviest body in 

 nature, and ridicule me for describing it as light. 



The nature of the acids formed by the union of azote and 

 oxygen is quite different from that of those formed when oxygen 

 and combustible bodies unite. They approach more nearly to 

 the acids formed by the union of oxygen with chlorine and 

 iodine. Indeed azote may be considered as approaching as near 

 the supporters of combustion as it does the combustibles. But 

 it coincides with neither, and must, therefore, in the present 

 state of our knowledge, stand by itself. 



; The simple combustibles 1 have divided into three sets ; 

 namely, 



1. Acidifiable Combustibles. 



2. Alkalifiable Combustibles. 



3. Intermediate Combustibles. 



The bodies constituting the first set are converted into acids 

 when they combine with some supporter of combustion. They 

 are all capable of entering into the composition of some gas or 

 Other; while none of the other two sets enter into any gaseous 

 compound at all. 



V I nave been blamed by some for placing arsenic and tellurium 

 among the acidifiable combustibles ; but my reasons appear 

 valid. As for osmium, I was uncertain where to place it, and 

 consulted Dr. Wollaston, whether he thought it likely that it 

 belonged to the first or second set. It was his advice that led 

 me to place it where it stands. The position is only provisional, 

 till a set of experiments be made to determine its true situation, 

 of which at present we know nothing. 



In his Review of my fifth edition, Mr. Brande ridiculed me 

 for considerinoj sihca as an acid. As this ridicule has not been 



