138 Mr. Denham Smith on the Compositioji of 



to whether it ought not to be considered as a product arising 

 from the decomposition of a portion of urate of ammonia by 

 the presence of a stronger acid, rather than as existing in the 

 specimen of guano in an uncombined state. This 1 cannot 

 consider to have been the case ; for although, like the other 

 solutions made by boiling water, it was faintly acid, yet in 

 No. 2 no free uric acid was discovered, although the urate of 

 ammonia in that specimen existed under precisely the same cir- 

 cumstances as in the analysis of the first sample ; and if uric 

 acid had been evolved in the first instance from its combina- 

 tion with ammonia, this salt surely ought not to have escaped 

 decomposition in the second case. I am therefore induced to 

 consider it as highly probable that, when the dung of which 

 guano is composed is freshly deposited, the uric acid which it 

 contains is not wholly in a state of combination with ammonia, 

 but that a portion exists as free uric acid. 



I must now allude to the production of the oxalate of am- 

 monia which is so constantly found in guano, being compelled 

 on this point to differ with Dr. Fownes. 



I am no friend to the hypothetical deductions which are 

 now so constantly employed in organic chemistry. They may 

 have their uses in leadhig the experimenter to the selection of 

 the right path and the proper mode of investigating organized 

 substances ; but the abuses they are apt to engender, too often, 

 I fear, more than counterbalance their advantages. Instances 

 of the elevation of hypothesis to the rank and consideration 

 due to ascertained and undoubted facts, and the erection of 

 other theories upon the first hypothesis, are to be found thickly 

 strewn throughout nearly every chemical publication of the 

 present day; nor are the works of some of the most distin- 

 guished chemists free from this objection, but rather might 

 be referred to as furnishing the most flagrant instances of 

 this indulgence of a luxuriant imagination. In accordance 

 with this usage, the sole requisite conditions to produce any 

 given organic compound which may be known or imagined 

 lo exist, is to commence with a something which need contain 

 but two elements, carbon and azote, and these are almost su- 

 perfluous ; add to this substance the oxygen of the atmosphere 

 and water, as much as may be sufficient, liberate hydrogen, 

 ammonia, oxygen, carbonic acid or azote, as may be neces- 

 sary, and there is the substance sought for — on paper. 



To return, however, to the formation of the oxalate of am- 

 monia : it must, I presume, be formed from the urate of am- 

 monia, because guano does not contain any other substance, 

 except by such a process as is detailed above, which can pro- 

 duce it ; in this, I believe, all chemists are agreed. 



