CHEMICAL TRANSFORMATIONS. 



97 



when its putrefaction has recommenced, in 

 consequence of its being kept in a warm 

 situation for some time. 



Yeast and putrefying animal and vegeta- 

 ble matters act as peroxide of hydrogen does 

 on oxide of silver, when they induce bodies 

 with which they are in contact to enter into 

 the same stale of decomposition. The dis- 

 turbance in the attraction of the constituents 

 of the peroxide of hydrogen effects a disturb- 

 ance in the attraction of the elements of the 

 oxide of silver, the one being decomposed, 

 on account of the decomposition of the 

 other. 



Now if we consider the process of the 

 fermentation of pure sugar, in a practical 

 point of view, we meet with two facts of 

 constant occurrence. When the quantity 

 of ferment is too small in proportion to that 

 of the sugar, its putrefaction will be com- 

 pleted before the transformation of all the 

 sugar is effected. Some sugar here remains 

 undecomposed, because the cause of its 

 transformation is absent, viz. contact with a 

 body in a state of decomposition. 



But when the quantity of ferment pre- 

 dominates, a certain quantity of it remains 

 after all the sugar has fermented, its decom- | 

 position proceeding very slowly, on account 

 of its insolubility in water. This residue 

 of ferment is still able to induce fermentation 

 when introduced into a fresh solution of su- 

 gar, and retains the same power until it has 

 passed through all the stages of its own 

 transformation. Hence a certain quantity 

 /of yeast is necessary in order to effect the 

 transformation of a certain portion of sugar, 

 not because it acts by its quantity in increas- 

 ing any affinity, but because its influence 

 depends solely on its presence, and its pre- 

 i sence is necessary, until the last atom of 



("""""These facts and observations point out the 

 existence of a new cause, which effects 

 combinations and decompositions. This 

 cause is the action which bodies in a state 

 of combination or decomposition exercise 

 upon substances, the component parts of 

 which are united together by a feeble affinity. 

 This action resembles a peculiar power, at- 

 tached to a body in the state ot combination 

 or decomposition, but exerting its influence 



.^beyond the sphere of its own attractions. 

 yVe are now able to account satisfactorily' 

 for many known phenomena. ^ 



A large quantity of hippuric acid mayTJe 

 obtained from the fresh urine of a horse, by 

 the addition of muriatic acid; but when the 

 urine has undergone putrefaction, no trace 

 of it can be discovered. The urine of man 

 contains a considerable quantity of urea; ! 

 but when the urine putrefies, the urea en- j 

 tirely disappears. When urea is added to a 

 solution of sugar in the slate of fermentation., 

 it is decomposed into carbonic acid and am- ! 

 monia. No asparagin can be detected in a j 

 putrefied infusion of asparagin, liquorice- 

 root, or the root of marshra allow (Jllthcm 

 ojficinalis. 



13 



It has already been ment oned, that the 

 strong affinity of nitrogen for hydrogen, and 

 that of carbon for oxygen, are the cause of 

 the facility with which the elements of azo- 

 tised compounds are disunited ; those affini- 

 ties aiding each other, inasmuch as by vir- 

 tue of them different elements of the com- 

 pounds strive to take possession of the dif- 

 ferent elements of water. Now since it is 

 found that no body destitute of nitrogen pos- 

 sesses, when pure, the property of decom- 

 posing spontaneously whilst in contact with 

 water, we must ascribe this property which 

 azotised bodies possess in so eminent a de- 

 gree, to something peculiar in the nature of 

 the compounds of nitrogen, and to their con- 

 stituting, in a certain measure, more highly 

 organized atoms. 



Every azotised constituent of the animal 

 'or vegetable organism runs spontaneously 

 into putrefaction, when exposed to moisture 

 and a high temperature. 



Azotised matters are, accordingly, the 

 only causes of fermentation and putrefaction 

 in vegetable substances. "3 



Putrefaction, on account of its effects, as 

 a mixed transformation of many different 

 substances, may be classed with the most 

 powerful processes of deoxidation, by which 

 the strongest affinities are overcome. 



When a solution of gypsum in water is 

 mixed with a decoction of sawdust, or any 

 other organic matter capable of putrefaction, 

 and preserved in well-closed vessels, it is 

 found after some time, that the solution con- 

 tains no more sulphuric acid, but in its 

 place carbonic and free hydro-sulphuric 

 acid, between which the lime of the gypsum 

 is shared. In stagnant water containing 

 sulphates in solution, crystallised pyrites is 

 observed to form on the decaying roots. 



Now we know that in the putrefaction of 

 wood under water, when air therefore is ex- 

 cluded, a part of its carbon combines with 

 the oxygen of the water, as well as with the 

 oxygen which the wood itself contains; 

 whilst its hydrogen and that of the decom- 

 posed water are liberated either in a pure 

 state, or as carburetted hydrogen. The 

 products of this decomposition are of the 

 same kind as those generated when steam is 

 conducted over red-hot charcoal. 



It is evident, that if with the water a sub- 

 stance containing a large quantity of oxygen, 

 such as sulphuric acid, be also present, the 

 matters in the state of putrefaction will make 

 use of the oxygen of that substance as well 

 as that of the water, in order to form car 

 bonic acid ; and the sulphur and hydrogen 

 being set free will combine whilst in the 

 nascent state, producing hydrosulphuric 

 acid, which will be again decomposed if 

 metallic oxides be present ; and the resu ts 

 of this second decomposition will be wa er 

 and metallic sulphurets. 



The putrefied leaves of woad (Isatis tinc- 

 toria,) in contact with indigo-blue, water 

 and alkalies, suffer farther decomposition, 

 and the indigo is deoxidised and dissolved. 



