130 



CHEMISTRY. 



mcnse, nd must be the work of ige of indefatigable 

 industry. 



This part of the subject naturally divides itself into 

 two Chapter*. In the first Chapter, wo shall give an 

 account of the different ingredicntl hitherto found in 

 annuals, mcli of them at least as have b-en examined 

 with any degree of accuracy; and, in the second, we 

 shall treat of the different member* of which animal 

 bodies are composed, which must consist each of various 

 combination* of the ingredients described in the first 

 Chapter. 



111)11 of 



Nature. 



MeiaU 

 found in 



,,!.c- .-: 



rro. 



MinfSMM 



Oold. 



SECT. XXXIII. Of 'Metals. 



Several metallic substances have also been found in 

 the ashes of vegetables, but their quantity is exceedingly 

 small ; so small, indeed, that without very delicate ex- 

 periments their pretence cannot even be detected. 



The metals hitherto discovered are iron, which is by 

 far ttie most common, manganese, and, if we believe some 

 chemi*ts, gold. 



1. Iron has been found in many plants ; the ashes of 

 salsola contain a considerable quantity of it. 



Scheele first detected manganese in vegetables. 

 Proust found it in the ashes of the pine, calendula, vine, 

 green oak, and tig-tree. 



3. With respect to the minute portion of gold extract- 

 ed from the ashes of plants by Kunkel, Sage, &c. it is 

 probable that it proceeded rather from the lead which 

 they employed in their processes than from the ashes. 



CHAP. II. Of Vegetation. See the articles BOTANY, 

 and VEGETABLE Physiology. 



CHAP. III. Of the. Decomposition of Vegetalle Sub- 

 iamcti. Sec the articles BREAD, FERMENTATION, Pu- 



THEFACT10X, VlXEGAR, and WlXE. 



BOOK V. 

 OF ANIMALS. 



Of aniaui*. WHLS we compare animals and vegetables together, 

 each in their most perfect state, nothing can be easier 

 than to distinguish them. The plant is confined to a 

 particular spot, and exhibits no mark of consciousness 

 or intelligence : the animal, on the contrary, can remove 

 at pleasure from one place to another, is possessed of 

 consciousness, and a high degree of intelligence. But 

 on approaching the contiguous extremities of the ani- 

 mal and vegetable kingdom, these striking differences 

 gradually disappear ; the objects acquire a greater de- 

 gree of resemblance ; and at last approach each other so 

 :iearly, that it is scarcely possible to decide whether 

 some of those species which are situated on the very 

 boundary, belong to the animal or vegetable kingdom. 



To draw a line of distinction, then, between animals 

 and vegetables, would be a very difficult task : but it is 

 not necessary at present to attempt it ; for almost the 

 only animals whose bodies have been hitherto examined 

 with any degree of chemical accuracy, belong to the 

 most perfect classes, and cgnscquently arc in no danger 

 of being confounded with plants. Indeed, the greater 

 number of facts which we have to relate apply only to 

 the human body, and to those of * few domestic ani- 

 mals. The task of analysing all animal bodies is im- 



CHAF. I. 

 Of Animal Substances. 



THE substances which have been hitherto detected Animal 

 in the animal kingdom, and of v. In 1. the different parts lubttaut?*. 

 of animals, us far as these parts have been analysed, arc 

 found to be composed, may be arranged under the fol- 

 lowing head.-.: 



8. Resins. 



9. Sulphur. 



10. Phosphorus. 



11. Acids. 



12. Alkalies. 



13. Eaiths. 



14. Metals. 



1. Gelatine. 

 2. Alhumcn. 

 15. Mucus. 



4. Fibrin. 



5. Urea. 



(j. Saccharine matter. 

 7. Oils. 



These shall form the subject of the following Sec- 

 tions. 



SECT. I. Of Gelatine. 



If a piece of the fresh skin of an animal, an ox for 

 instance, after the hair and every impurity is carefully 

 separated, be washed repeatedly in cold water till the 

 liquid ceases to be coloured, or to abstract any thing; 

 if the skin, thus purified, be put into a quantity of pure 

 water, and boiled tor some time, part of it will be dissol- 

 ved. Let the decoction be slowly evaporated till it is 

 reduced to a small quantity, and then put aside to cool. How ob 

 When cold, it will be found to have assumed a solid ' a ' 

 form, and to resemble precisely that tremulous substance 

 well known to every body under the name ( jelly. This 

 is the substance called in chemistry gelatine. If the eva- 

 poration be still farther continued, by exposing the jelly- 

 to dry air, it becomes hard, semitransparent, breaks with 

 a glassy fracture, and is, in short, the substance so much 

 employed in different arts under the name of glue. Ge- 

 latine, then, is precisely the same with glue ; only that 

 it must be supposed always free from those impurities 

 with which glue is so often contaminated. 



Gelatine is semitransparent, and colourless when pure. j ts 

 Its consistency and hardness vary considerably. The ties, 

 best kinds arc very hard, brittle, and break with a glassy 

 fracture. Its taste is insipid, and it has no smell. 



When thrown into water it swells very much, but 

 does not readily dissolve ; and when taken out, it is toft 

 and gelatinous ; but whin allowed to dry, it recovers its 

 former appearance. If it be put in this gelatinous state 

 into warm water, it very soon dissolves, and forms a so- 

 lution of an opal colour, and the more opukc according 

 to the quantity of gelatine which it contain*. Tremu- 

 lous gelatine dissolves in a very small portion of hot wa- 

 ter; but as the solution cools, it gelatinizes afrt-sh. If 

 this solution, as soon an it assumes the tremulous form, 

 be mixed with cold witer and shaken, a complete solu- 

 tion takes place. 



