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and wax, are more susceptible of change than woody 

 fibre when exposed to air and water ; but much 

 less liable than the other vegetable compounds ; and 

 even the most inflammable substances by the absorp- 

 tion of oxygene, become gradually soluble in water. 



Animal matters in general are more liable to de- 

 compose than vegetable substances ; oxygene is ab- 

 sorbed, and carbonic acid and ammonia formed in the 

 process of their putrefaction. They produce foetid 

 compound elastic fluids, and likewise azote : they af- 

 ford dark coloured acid and oily fluids, and leave a 

 residuum of salts and earths mixed with carbonace-. 

 ous matter. 



The principal substances which constitute the 

 different parts of animals, or which are found in their 

 blood, their secretions, or their excrements, are gela- 

 tine, fibrine, mucus, fatty, or oily matter, albumen, 

 urea, uric acid, and different acid, saline, and earthy 

 matter. 



Of these gelatine is the substance which when 

 combined with water forms jelly. It is very liable to 

 putrefaction. According to M. M. Gay Lussac and 

 Thenard, it is composed of 

 47.88 of carbon, 

 27.20*7 oxygene, 

 7.914 hydrogene. 

 16.998 



These proportions cannot be considered as defi- 

 nite, for they do not bear to each other the ratios 

 of any simple multiples of the number represent- 

 ing the elements j the case seems to be the same 



